the broad-skulled pseudocreodi

ANNALS OF THE NEW YOKK ACADEMY OF SCIENCES VOLUME XXXVII, PAGES 163-257

MAY, 1938

THE BROAD-SKULLED PSEUDOCREODI"

ns R O U I ~ I ~ T HOWLAND DENISON

IN L'ltOUUCTlOh' .

CONTENTS

. . . . . . . . . . . . . . . . . . ,.. . . . . . . . . . . . . I I I ~ T O I ~ Y or TIIK Sruuu 01' TIII-: (;rtoui* . . . . . . . . . . . . . . . . . 164

SYH'CELIATIC I ~ R V I B I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1GG

(;p:OLOOICAL. A N D C k : W i l t A l ~ i l l C A l . D I S P H I B U T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . 18;1

SrltU~UltAL A X V 1:Uh'trrlOh'Al. I':VOI.UTION . . . . . . . . . . . . . . . . . . . . . . 187 Teeth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Imwr .In\v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

. . . . . . . . . . . . . . . . . . . . . . . . . . . . Skriiuin . . . . . . . . . . . . . . . . . . . . . . . . . Fore limb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 Hind l imb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

h I)AITATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1;cedjng Adnptutiori . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Locomotor Adaptution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

CI:NEIIAL RLELATIONSIIIPB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Itclationships of the Limnocyoninne. . . . . . . . . . . . . . . . .

kIntioiisliips.ol the Pnlaeonictinee . .

Possibility of Devcendnnta of tlic Oxyiciiidnc . . . . . . . . . . .

Origin of the Limnocyoninae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

Origiu of thc Oxyucnidac. ........................ :. . . .

l ' l l Y l , o l ~ l ~ ; N Y ..................... ........................ 248

~ I I I I . I O G I t A I ' I I Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

I h' I ) EX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256

h w a n l o d an A. Crossy hlorrlson Prlze In Natunl Sclonco. in 1937 by- the -NewY6rk- Acrcleiny of Sc1enca-x Ccntennlnl Fund.

Puhlimtlon motlo povslblo througll a grant from the income of the

(103)

164 A N N A L S NEW YORK ACADEMY OF SCIENCES

INTRODUCTION

The present paper deals with those Upper Paleocene and Eocene carnivores grouped by Matthew (1909, p. 409; 1915, p. 46) in the Oxyaenidae. Four distinct phyla or subfamilies are represented, of which the Oxyaeninae and Palaeonictinae are retained in the family Oxyaenidae in this paper, while the LimnGcyoninae and Machair- oidinae are referred to the Hynenodontidae. An attempt is made to trace the structural and functional evolution within the four groups, to determine the origin and phylogeny of each line, and to give a systematic revision.

A Iargc part of the material examined is in the collection of the American Museum of Natural History. Other museums visited which contain specimens of this group are the Peabody Museum at Yale, the Museum of Comparative Zoology at Harvard, the Geological Museum of Princeton University, the U. S. National Museum, and the Carnegie Museum. The writer is indebted to J. J. Burke, C. L. Gazin, Walter Granger, W. I(. Gregory, G. L. Jepsen, A. S. Tlomer, W. B. Scott, G. G. Simpson and M. R. Thorpe of the above museums for permission to study their material and for assistance in this work.

HISTORY OF-THE STUDY OF THE GROUP

Charles d’Orbigny in 1836 described the trigonid of a lower molar from the Sparnacian (Lower Eocene) of Meudon, France, as “Loutre”; this fragment probably belongs to Palaeonictis and is the first speci- mftr of the broad-skulled Pseudocreodi to be mentioned in the litera- ture. In 1842, de Blainville named the genus PaZaeoniclis, and described and figured i t from better material, but considered it to be a viverrid; it was not until after the discovery in North America of more complete material of related genera tha t its true affinities were recognized. The two ot&&wpean forms, both from the Phosphor- ites of Quercy, were described by Filhol, Thereutha’um in 1876 and “Ozyaena” galliae in 1882. His descriptions were supplemented ._

later by Lydekker (1884), Schlosser (1887), Martih(1906) and-&.&; (19 15).

DENISON: I’SEUDOCREODI 165

Most of the broad-skulled Pscudocreodi occur in North America, and thus it is the paleontologists of this continent who figure most prominently in the study of the group. Leidy in 1870 described the first form, Patriofelis irlta. In 1872 Marsh described numerous new gcnera and species from the Bridger or Middle Eocene. Of the early workers, however, it was Cope who added most to our knowledge of the group. His descriptions of Lower Eocene specimens, though val- uable, are not his most important contribution; for he was the first to realize the general relationships of the Creodonts, and the ancestral position they occupy relative to the fissipedes. As early as 1880 (A) he had achieved a classification which, though leaving much to be desired, was a substantial basis for further work. In 1895 in Den- mark, Winge produced a fundamentally different classification of Carnivora, based on the basicranial region, on foot structure, and more especially on his theory of cusp homologies and evolution.

At the close of the nineteenth century Scott, Wortman, and Osborn produced important papers on the group. Scott in 1892 revised the classification of Cope somewhat. In 1894, Wortman produced the earliest thorough osteological description of a member of the group, and also made the first satisfactory attempt to determine adaptation. In 1901 and 1902 he made a complete study of the Marsh collection of Middle Eocene creodonts. Wortman was a strong advocate of the theory of derivation o,f the seals from Patriofelis aiid of the Felidae from the Palaeonictidh, two ideas now completely discredited. Os- born contributed sevkral papers describing new forms from the Wasatch and Huerfano beds, and the first known North American Upper ‘Eocene member of the goup , whose affinities he did not correctly determine.

Mntthew is the outstanding figure in the study of the group in the twentieth century. In numerous papers he improved greatly the classifications of Cope, expressed the views on the relationships of the creodonts which are now generally accepted, and described many new genera and species, as well as furnishing more complete descriptions of earlier named forms. Other descriptive papers have been written by Peterson (1919) on the Upper Eocene forms, Jepsen (1930) on specimens from the Upper Paleocene especially, and Thorpe (1923) on Middle Eocene creodonts. Important work on the stratigraphic position of these fossil mammals has been done by Teilhard de Chardin in Europe- and Granger, Osborn, Matthew and Simpson in North America.

1 titi A N N A L S N E W YOllK ACADEAf Y OF SC'IENCL%#S

SYSTEMATIC REVISION Supcrfaiiiily PSEUDOCKEODI Matthew 190'3 (327)

Cntiiassiuls M + 01' M$. Uiigual phalailgcs fissured :it tip. h i i n -

bar zyppopliyses cyliiidrical or rvvolute. This supcrfaniily is distiiiguiulic~d froiii the Acrec'di (Mes~iycli idac

and Arctocyonidac) by the prcsciicc of specialized cariiassial tccth, and from the Eucreodi (Miacidac) by the position of the csrnassials in thc tooth row, the cleft unguals, and thc more cornplcx lumbar zygapophyscs. I t includes the Oxyaenidac and Hyscnodontidac.

1;:iiiiiIy OXYAENIDAE Copc 1877 (89)

Yf singlc-rooted or nhsent; P3 with protocone progressively devc4- oped; M i functioning as carnassials; M' transverse or absent; M; absent in all known genera; check tooth-row short. Jaw short and deep, with robust symphysis and short, bluntly rounded nnglc. Face moderately to very short; basicranial region broad; preglcnoid crest present. Body robust. Sacrum lacking distinct anterior process from lateral mass. Feet pentadactyl, short and spreading, planti- grad(* or subplantigrade. Unya l s flattened dorso-ventrally. Proxi- mal fibular facet of tibia facing mostly vc~ntrally. Fibulo-cal(.aiic.:ir irrticulstion small or usually absent. Astragalar body much flattciivd, with w r y shallowly grooved trochlcnr surface. Cuboid-astrag:ilar facet large, facing rather proximo-distally. As originally defined by Cope (1877, p. 89), this family iiicludcd

_Stl(polqphus, Oxyaena, Pterodon and perhaps Pdriofelis. Matthew i n 1909 (p. 409, 410) included 0zyaen.a; Palrio$elis, Palaeonictis and Ambloctonus in thc Oxyaeninse, and Limmcyon, Thinocyon, Omjaeno- don, Tiiereutherium and Machaeroides in the Limnocyoninac. In 1915 (p. 42) he implied the separation of Palaeonictis and Ambloctonus from the Oxyaeninac. The family is redefined here to contain only the Oxyacninac of Matthew's 1909 classification, subdivided as suggested in his 1915 paper.

Subfamily OXYAENINAE Wortman 1902 (11G)

MT larger than MT; MA and P* with elongate metastylcs. Aiiglc of jaw projecting very slightly.

This spbfamily is uscd to include the same genera az in Wortman's 1902 paper, but is redefined to distinguish i t from the Palaeonictinae instead of from the Limnocyoninac. Hay also used Oxyaeiiinnc as 3

DENISON: PSEUDOCREODI 167

new subfamily in August 1902, but credit for thc name gocs to Wort- man, whosc papcr appeared in Fcbruary, 1902.

DIPSALIDICTIDES, NEW CENUB

. Genotype: Dipsalidiclis amplus Jepsen (1930 B). Lower molars as in primitive spccics of Oxyaena, subequal in size, trigonids wider thnn long, and with large metaconids and talonids. M' very wide transvcrscly, with short metastylc. hlz transvcrsc, less rcduced than in Oxyaena. P+ with smnll nntcrior b&al cusp; PA rclntivcly widc transverscly, with largc protoconc lobc; Ps simple, lncking protoconc.

The type of thc gcnus Dipsalidictis is rcferrcd to Oxyaena, making ncccssary thc crcation of a new gcnus for this species, which differs rnnrkedly in its widc hlL with smnll metastyle and unrcduced proto- conr, and in its widc P*. I t is probable that thesc characters arc primitivc, sincc thc lowcr tccth, M s and Pz arc less progressivc than in othcr members of thc Oxyneninnc; but thcrc is n possibility thnt thcy rcprcsent n specialization in a differcnt direction from othcr mcmbcrs of the subfamily.

Dipsalidictides amplus (Jcpscn) 1930 (B, 128, pl. 4, figiires 1 nnd 2)

~ I l ~ l J I l ~ S 6, 8

Lowcr Eowiic, Loww Gray null (Sand Coul~v) , Clark Fork Basin, Wyoming. Sizc small; Im& MT-T 20.7 mm.

OXYAENA c'opc 1874 (599)

Dcntition, +I+, +, +, f, MS tranwcrse and rcduccd; M+ with protocone of moderate size. :ii,tl rnrtnstylc not cxcrssivcly rlongate; P3 with protocone nbscnt to large. Mrr with talonid and metaconid lnrgc to modwatcly smnll, and with shcsr angle progrrssively reduced,- but not pnrnlleling jaw; MT considcrahly reduced in ndvanced spccies, its trigonid not extcndcd nntcro-posteriorly. Jaw moderately short and deep. Facial rcgion not excessively shortened, nor palate greatly widened. Body, limbs :iwI feet slender to moderately robust.

r-b Oxyaena platypus (Mntthrw) 1!)15 (05, figures 5 4 4 ; )

FIGUI~EB 6, 11, 14, 25n nnd 2OA, D, E

Uppcr Palcocenc, Clark Fork, Bighorn Basin, Wyoming. Size

This is the type of Matthew's genus Dipsalidiclis, whish he consid- But it is definitely nn

smallest of genus; length MT-T 17.1 mm.

crcci to bc a member of thc Limnocyoninae.

Teeth slender.

168 ANNALS NEW YORK ACADEMY OF SCIENCES

oxyaenine, which dif&rs from other primitive species of Oxyaena only in its smaller size.

Oxyaena aequidens Matthew 1915 (47, figure 41)

FIOURE 6

Upper Paleocene, Clark Fork, Bighorn Basin, Wyoming. Size moderate; length MT-IF 26.6 mm.; teeth relativcly robust; a primitive species.

Oxyama transiens Matthew 1915 (47, figures 42-43)

Lower Eocene, Lower Gray Bull (Sand Coulee), Clark Fork Basin, Size small; length MT-V 22.5 mm.; slightly advanced be- Wyoming.

yond O q a e n u platypus.

Oxyama gulo Matthew 1915 (53, figures 47-48)

FIGUREB 5, 6, 8, 11

Lower Eocene, Lower Gray Bull (Sand Coulee) to Middle Gray Bull, Bighorn, Clark Fork and Wind River Basins, Wyoming. Size moderate; length M T-F 26-29 mm.; intermediate in specialization.

Oxyama intermedia, NEW BPEClEB

FIGURE 5

Type: Amer. Mus. No. 25183, lower and upper jaws with teeth, sku11 fragments and some skeletal parts.

Paratype: h e r . Mus. No. 15184, lower jaws with teeth. Both from the Lower Eocene, Middle Gray Boll, Bighorn Basin, Wyoming.

Specific characters: Size large; length MT-3 32.5-34. mm. ML with protocone little reduced; Pz with moderately strong protocone lobe; MT somewhat smaller than Mx (MT/MT .90-.91); trigonid of Mu longer than wide (W/L .91-.97); talonid of MY moderately large (36- 39% of length of tooth); angle of shear fairly high; P+ rather robust. This species includes most of the Middle Gray Bull specimens for-

merly referred to Oxyaena jorcipafa. Although it agrees with the latter in size, it is definitely more primitive than the typical Oxyaena jorcipafa, being of about the same stage of evolution a2 its smaller contemporary, Ozyaena gub. It may-be distinguished from both 0. lupina and 0. jorcipatu by its wider trigonids, larger talonids and metaconids on the lower molars, less reduced MT, larger protocone on M'; most of these characters result in a less perfect carnassial shear. The type specimen has been figured by Matthew (1915, figures 45-46).


Oxyaena forcipata Cope 1874 (600)

FIGURES 27, 31

Lower Eocene, Almagre and ? Largo, San Juan Basin, New Mexico; Upper Gray Bull to Lost Cabin, Bighorn Basin, Wyoming; Huerfano A, Huerfano Basin, Colorado. Size large; MT-I 31-34 mm. M' with protocone considerably reduced; Pn with well developed protocone; MT much smaller than Mz (MT/MT .77-.86); trigonid of Mu longer than wide (W/L .77-.79); talonid on MT considerably reduced (2&34% of length of tooth); angle of shear moderately low; PT robust.

This species is redefin d to include only those specimens which resemble the type in the a vanced development of the carnassial shear. The distinctions from J intermedia are noted above, but there are many intermediate forms. It is distinguished from 0. Zup'na mostly by its larger size and greater robustness, especially of the premolars. Both the type and paratype of 0. para'ulis Matthew (1915, p. 55, figure 49) are referred to this species; their size is only slightly larger, the canine is not more robuat, as Matthew stated, and the broad heel of P+ is by itself an unreliable character t o distinguish a separate species. The type of 0. forn'paia is figured by Cope (1877, pl. XXXVI, figures 1-6).

Oxyaena lupina Cope 1874 (599)

FIGURE 6

Lower Eocene, Almagre and Largo, San Juan Basin, New Mexico; Huerfano A, Huerfano Basin, Colorado; ? Lysite, Wind River Basin, Wyoming. Size moderate; MT-T 28-29.5 mm.

This is an advanced species, distineished from 0. jorcipala by the characters noted above. Typical specimens are all from New Mexico; the Huerfano forms (0. hu@amensis Osborn 1897, p. 255) are slightly larger and more advanced; the Lysite specimen (Princeton No. 13444) is slightly larger, but probably closely related. The type specimen is figured by Cope (1877, pl. XXXV, figures 1 4 ) .

Oxyacna ultima, NEW SPECIES

FIGURES 1, 5

Type: Harvard, Mus. Comp. 2001. No. 3423, right lower jaw with CT to Mu; skeletal fragments; from the Lower Eocene, Lost Cabin, North Fork of Wind River, Wind River Basin, Wyoming.

170 A N N A L S NEW Y O R K ACADEMY OF SCIENCES


Specific characters: Size large; MT-T 32 mm.; PT-MY 81 mm.; lcndh MT 19.8 mm. MI- much smaller than MT; trigonids of lowcr molars narrow, talonids r a the r small; mctaconid of MH vcstiginl; shear angle-low; P7 compressed, with large anterior basal cusp.

This species is thc size of 0. forcipala, from which it diffcrs markcdly in the slender, compressed lower premolars; W/L of P+ is only .52, as compared to .57-.60 in 0. forcipatu. This charactcr agees bcttcr with 0. lupinn, of which this species may be a largc dcrivntivc.

PROTOPSALIS Cope 1850 (I), 745)

Mz with very small talonid, vestigial mctaconid, and well dcfincd shcaring surface on the enlarged paraconid and protoconid; MT con- sidcrnbly rcduccd, with smnll mctaconid closely applied to protoconid, and with trigonid CUSPS lcss drawn out nntcro-posteriorly than i n Pdriofelis. R;I' with protocone smnll, but largcr than in Pdriofelis, and with cxternal cusps less elongate than in Patriojelis; Pz with largc protoconc. Jaw deep.

Protopsalis has not quite attained the Patriofelis stage of carnnssinl construction, but is intermcdiate between the latter genus and Oxy- aenn. nccnusc of this fnct, it is retained here as a distinct gcnus.

* Protopsalis tigrinus C o p 1880 (JI, 715)

Ftanrt~, G

Lowcr Eoccnc, Lost Cabin, Wind Rivcr Bnsin, Wyomini. Sizc For illustrntions of typr, scc Cop(> 1884 Inrgc; lcngth h1.r 25 mm.

(A, pl, XXVh, figurcs 1-7).

Dentition, .I!g, +, g, +. PATRIOFELIS J.citly IS70 ( 1 0)

M I absent; M L with protoconc vcstiginl, and with external cusps, especially the metastylc, grcetly clongatc; P3 with lnrgc protocone lobe; Pg two-rooted, but much widened in- tcrnally; P i abscnt. MT with talonid nnd metaconid abscnt or vcstigial, and with 'elongate shearing surface approximately parnlld to jaw axis; MT with trigonid cusps flattened transverscly mid drawti out h,rro-posteriorly , and with singlc~cusped, shearing talonid; Ps-7 with large, distinct anterior basal cusps. Skiill vcry short and brond. Body and limbs robust; fcct very short arid spreading.

Jaw short and deep.

Pattiofelis coloradensis Mntthew 1W'J (in Osborn, 1909, 9G)

Middle Eocene Huerfsno%+uerfzrm%win, Colorado. Smallest __ ----J

of genus; P r M ? r 60 mm.; MT-T approximately 26 mm.


This specimen was first described by Osborn (1897, p. 256) as P. ulla, then distinguished by Matthew (1909, p. 96) as this species, and

finally referred to Ambloctonus by Matthew in 1915 (p. 62). It certainly is distinct from P. ulta because of its small size and other char-

DENISON: PSEULMCRBODI 173

acters. The absence of MT and the worn condition of the teeth give rise to the confusion as to its proper generic reference. In the very broad, robust lower premolars this specimen may resemble Ambloc- tonus slightly more than Palriojelis, but thesc teeth are very similar in the two genera. Rilp appears relatively smnll for Pabiojelis, but this is due largely to the fact that it is greatly worn; in details of its construction it is closer to Palriofelis. The jaw gives the most con- clusive evidence of relationship with Palriofelis; the form of the insertion areas for the pterygoid and temporalis muscles are exactly as in other species of the latter genus, and the angle is very short as in all Oxyaeninae, whereas it projects much more in the Palaeonictinae. The type, and only specimen, is figured by Osborn (1900, figure 8).

Patriofelis compress, NEW BPECIEB

FIOURE 2

Type: h e r . Mus. No. 17017; left lower jaw, nearly complete, with C r M 3 ; right P+ and CT; limb fragments. From the Middle Eocene, Huerfano B, Big Sand Draw, 3 miles northwest of Gsrdner, Huerfnno Basin, Colorado.

Specific characters: Size fairly small; P?r-Mr 65 mm.; MT-H 28 mm.; length Mp 17.4 mm. PT shorter than M p ; lower premolars and canine less robust than in other species of the genus.

This species is sharply distinguished from all the others in the genus by its relatively slender premolars. It is smaller than P. jerox and P. u h , and slightly larger than P. coloradensis.

Patriofelis ulta Leidy 1870 (10)

Middle Eocene, Bridger B, Bridger Basin, Wyoming; ? “Lower Bridger,” Wind River Basin, Wyoming. Size moderately large; P r M a 75.5 mm.; My- 32.2 mm.; jaw shallow; premolars robust; P+ larger than MT. (Figured by Leidy, 1873, pl. 11, figure 10.)

Patriofelis ferox (Marsh) 1872 (B, 202) FIOUREB 6, 6 ,8 , 11, 16, 19, 20, 23, 24B, 26C,26C, 27, BB, BB, 30B, 31

Middle Eocene, Bridger GD, Bridger Basin; Washakie A, Washa- kie Basin; ? “Bridger C,” Wind River Basin, Wyoming. Size largest of genus; PT-MI~ 78-84 mm.; MT-T 35-36 mm. Jaw very deep and heavy; premolars and CT robust; PT about equal to M.r in length.

Synonyms are Limnofelis ferox Marsh 1872 (B, p. 202), Oreocyon latidens ,Marsh 1872 (C, p.. 406), and Aelurotherium Adams 1896 (p. 442). That Aelurotherium is the milk dentition of P. ferox is confirmed by a specimen in the U. S. National Museum (No. 13318) with D P z x and MT erupting. The Wind River Basin individual


(Wood, Scton & Hares, 1936, p. 394) is slightly smaller, but otherwise close to typical specimens. This species is cornplctcly dcscribcd by Wortrnnn (1894) and Matthew (1909, p. 417-432).

SARKASTODON Grnnger 1038 (1)

Dentition, 9, +, %, 4. Cheek teeth much as in Patriojelis; M' cxces- sivcly shearing, with vestigial protocone; premolars robust; Pg probably with internal root; lower premolnrs extremely wide, with small anterior basal cusps;.canines and Ia vcry large and robust; I 1 vcstigial and 1' absent; only a singlc, small lower incisor. Jnw very short nnd dccp. Skull vcry short, broad nnd robust.

Saricastdon mongoliensis Grnnger 1038 (1)

Uppcr Eoccnc, Irdin Mnnha formntion, Inncr Mongolia. Size very large; PT-Mv' 160-164 rnrn.; MT-T 76-77 rnrn. This is the largest known carnivorous rnnrnmnl with the cxccption of the rnesonychid, A drewsarchus.

Subfnmi ly PAW EONI CTINA E, N E w Ma smallcr thnn MT; M I and P i with short rnctnstyle; nnglc of

jnw bluntly rounded, but projecting considernbly. This group resembles the Oxyneninne in skul l nnd skclctal char-

actcrs, but differs in thc teeth, the carnnssial adnptation bring lcss pronounced, and the posterior shearing tccth being rrthiccd in six(.. Palaeonicfis and AmbloclrtniLs hnvc bccn rcfcrrcd to a sepnratc! family, Ambloctonidac by Cope (1877, p. SO), or Pnlaeonictidnc by Oshorir (in Osborn & Wortrnnn, 1892, p. 104), to subfnrnily Palaconictitliiii of the family Palaconictidac! by Wingc (1924, p. 177), nud to thc'aub- family Oxyncninnc of the family Oxynenidnc by Mntthcw (1909, p. 409) and others.

DIPSALODON Jcpscn 1030 (A, 524)

MT very slightly lnrgcr thnn Ms; lower molars primitive, with unrcduced metnconid, no carnsssinl specialization, and Inrgc' b n & d heels; hypoconid, hypoconulid and rntoconicl distinct on MT; lower premolars and CT robust; PT wit11

large anterior basal cusp; jaw deep and strong. A primitive oxyaenid, not far different from early species of Oxyaena in its lower tcct,h, hut showing tendencies towards Palagoniclis.

Dipsalodon matthewi Jepsen 1930 (A, 524)

Lower dentition, ?, 1, 4, 2.

FIQUREE 6, 11

Upper Paleocene, Uppermost Clark Fork, Clark' Fork Basin, Wyoming. Size rather large; PT-MT npproximately 81 mm.; MT-T

27.5 r ir i i i . Arlic-r. Rlus. No. 160G8 from the snmc liorizor), dccr ibd by RJatthw (1!)15, 1). 47) LS I ‘ ? O x y ~ n a sp. iriiioiii.”, is referred licrc doubtfully. I t iiiclu$cs much worn upper tcctli of upproxirnutcly tlu: wiiic size :LY D. nrcrflhewi; PA aiid hl’ Ii:ivo relatively short p:rrastylwi :itid iiict:Lstylcs, ill which thcy rcscmblc Palueoniclis.,

PALAEONICTIS Dlniiiviilc 1842 (79) Dcirtitioii, 3 , +, +, i. M s considcrably reduced, of tubcrculo-scctor-

ia1 typv, with mctaconid modcrate to vestigial, paracoilid arid protoconid not much enlarged, talonid littlc rcduccd; trigonid of MT not eloilgate antero-postrriorly ; lower prcmolars robust, with lurgc. :witc.rior Lava1 cusp on P T ; &I1 vcstigial; jaw relatively Jiq, arid robust.

This gciius is distinguished from Dipsalodon by the grcntcr rcduction of Mz. and its mctaconid, and from Ambloclonus by thc tubcrculo-sectorial form of M u , its largc talonid, and by thc rclntivcly short trigonid of Mr.

Palaeonictis gigantea Blainvillc IS42 (76-7!), pl. XIII) Lower Eoccnc (Sparnacian), Lignites de Muirancourt, ncar Noyon,

aid Conglomkrat de Meudon, near Paris, France. Sizc smaller than P. occidentalis; &IT-T 19-21 mm.; MT less reduced than in P. occidcn- lalis (h1T/h1T 1.14-1.26); Mu with large metaconit1 arid thrcc distirwt taloiiid cusps.

This species is very closc to P. ocdcn fa l i s of WyoiniiiE, but riiay be slightly more primitive. Thc typical specinicns arc from thc Lignites de Muirancourt; probably related is a trigonid of a lower molar from the ConglomCrat dc Meudon, originally described by d’thbigny (1836, p. 287) aa “Loutre.”

Palaeonictis occidentalis &born I SD2 (30)

F I G I J I ~ E ~ 5, 6, 9, 11, 14, 16

Lowcr Eoccnc, Lower Gray Bull (Sand Coulee) to Middle Gray Bull, Bighorn Basin, Wyoming. Size modcratc; MT-T 23.5-24.5; MT/MT 1.25-1.45; metaconid of Mr moderate to vestigial.

Ambloclotius pn’scus of Matthew (1915, p. 60) must be rcfcrrcd’hcrc. The type specimens differ from the type of P. occidentalis in several characters, but they do not warrant even a specific separation. The canines of A . priscus are smaller, but this is a variable character, perhaps sexual, in this group. Mg is a small, transverse, two-rooted tooth in the type of A. priscw, whereas it is a single-rooted nubbin in the type of P. occidentalis; but such a variation is to be expected in a vestigial tooth, and is exceeded in a single spccies of cat, Pelis concolor.

176 A N N A L S NEIY YOHh' ACAVEAJY OF SCIENCES

hl3 has a vestigial metaconid and moderately distinct talonid cusps in A . pn'scus, but other specimens show all the intergradations to the type of P . occidenlalis where the metaconid is moderately strong and the talonid cusps are not clearly separated. Other differences in the cingula and acccssary cusps of the lower premolars are clearly individual variations. On the other hand, the two types agree closely in size, tooth pattern, and even in the surface markings on the skull.

AMBLOCTONUS Cope 1875 (A, 7) Dentition, Pi, M$, M.r considerably smaller than MI, with talonid

small or lacking, metaconid absent, and with protoconid and paraconid enlarged and connected by a curved shearing ridge; MT with trigonid cusps elongate and arranged in a crescent, and with large, basined talonid; lower premolars very broad; P+ with large anterior basal cusp; Ma probably present, but vestigial; jaw short and deep.

Ambloctonus sinmus Cope 1875 (A, 8) FIGURES 6, 11

Lower Eocene, " Wasatch" (= ? Largo), San Juan Basin, New Mexico. Size moderate; length MT 15.5 mm.; Mx 12.3 mm.; M?r with small talonid; lower teeth robust. (Figured by Cope 1877, pl. XXXIII, figures 1-10.)

Ambloctonus hyaenoides.Mattliew 1915 (61, figures 50, 52) F I O U ~ ~ E 6

Lower Eocene, Largo, San Juan Basin, New Mexico. Size about that of A . sinostq length MT 16 mm.; M r 12.5 mm.; MT with talonid practically absent; lower teeth narrower and less robust than in A . sinosus.

This species includes as paratype one of the specimens referred by Cope to A . ~ ~ R O S U S (1877, pl. XXXIII, figure 11).

Ambloctonus major, NEW SPECIE6

Type: Amer. Mus. No. 16853; left lower jaw fragment with DPT and

Specific characters: Size larger than A . hyaenoides; length MT 19

This specimen was referred by Matthew (1915, p. 61, figure 53) t o

MT; fromt he Lower Eocene, Lost Cabin, Bighorn Basin, Wyoming.

mm.; entoconid of MT larger than in A . hyaenoides.

A . h y a e ~ d e s , but is separated because of its distinctly larger size. '> I -

PAROXYAENA Martin 1906 (598)

18 much enlarged, 12 reduced, 1-1 absent; P l probably lacking protocone; PE-5 three-rooted, with large, wide protocone lobes, small metastyle and anterior cusps; face very short.

Dentition, 6, +, 4, &.

DENISON: PSEULWCREOLN 177

P&oxyaena galliae (Filhol) 1882 (120)

FItiUHE 5

Upper Eocene, Phosporites de Quercy, Mouillac (near Caylux) and Escamps (near Lalbenque), France. Size rather large; Pl-k 57 mm.; length P' 17 mm.

This form was described originally as a member of the genus Ozgaena by Filhol in 1882. Martin in 1906 referred it to a separate genus, Paroxyaenu, because he considered its similarity to Oxyaena to be due to convergence. Its resemblance to Oxyaenu, however, is not very

Pi, with its short metastyle, small anterior cusp, and wide protocone lobe resembles the Palaeonictinae more closely. The incisors and P' resemble both the Oxyaeninae and Palaeonictinae. It is placed in the latter subfamily only provisionally. (Figured by Filhol 1884, pl. VII, figures 6 and 7.)

- close.

Family HYAENODONTIDAE Leidy 1869 (38) P) two-rooted, except in some specialized genera; Pa lacking distinct

protocone; MJ or MP functioning as main carnassials; MQ present or absent; cheek tooth row moderate to long. Jaw long and shallow to moderately short and deep, with symphysis weak to fairly robust, and angle long, slender, projecting and upcurved at tip. Face long to moderately short; basicrsnial region narrow to moderately wide; no preglenoid crest. Body more slender than in Oxyaenidae. Sacrum with distinct anterior process from lateral mnss. Feet pentadactyl, long and slender to moderately short and broad, digitigrade to subplantigrade. Ungual phalanges laterally compressed. Proximal fibular facet of tibia facing mostly laterally. A well developed fibulo- calcanear articulation. Astragalar body moderately deep; trochlear surface shallowly grooved. Cuboid-nstragalar facet small or absent, facing mostly mesio-laterally.

The definition of the family is modified here so as to include the Limnocyoninae and Machaeroidinae, as well as the more typical hyaenodontids, the Proviverrinae and Hyaenodontinae.

Subfamily LIMNOCYONINAE wortman 1902 (1 17) Carnassial teeth M&; MS lost early; CT not reduced and CP not

enlarged. Skull relatively short and broad. Jaw lacking ventral flange anteriorly.

This group is distinguished from the Machaeroidinae by the absence of any sabre-tooth specializations, and from the Proviverrinae and Hyaenodontinae by the position of the carnassials and the breadth of

178 l l N N A L S NElY YOl(K ACADEhfY OF S C l E N C B S

tlic skull. The r('ason for the inclusion of this group in the Hyucriio- doiitidac will bc discussed below.

PROLIMNOCYON Mnttlicw 1915 (67) Uciititioii, &, $, 2, 4: * M$ siriall or vestigial; M 3 with distiiict

iiictaconc: aiid fairly short parastylc; M' widc transvcrscly, with uiircduccd protoconc; P3 thrcc-rooted; MT-Z subcqual or MT sliglitly rcduccd; trigonid of MT about a3 widc as long; PT two-rooted or with roots connate.' Jaw long and shallow. Skull inoderatcly narrow, with facial region long.

This is thc most primitive genus of thc subfamily, appronchiig vvry closc to thc Proviverrinire.

Prolimnocyon atavus Mtrttliew 1'315 (cis, figurea 5 7 4 1 )

Frcwwe 7. 10, 12, 15, 17 Lower Eoccnc, Lowcr Gray Bull (Sand Coulec) to Upper Gray Hull

and 7 Lysitc, Bighorn Basin, Wyoming; ? Almagre, San Juan Basin, Ncw Mcxico. Sizc small; MT-JJ 13-16.5 mm.; MH smaH, with two roots distinct or partly connate; jaw shallow.

Prolimnocyon robustus Matthew 1916 (70, figures 57 and 62)

Lowcr Eocvii~, Middlc Gray Bull, Bighorn Basin, Wyoiniiig. Sizc large; Mr-3 upproximately 21 mm. ; MH two-rooted, less roducctl than in P. atavus; j aw dccpcr than in P. alavus.

Prolirnnocyon antiquus Mntthcw 1015 (70, figure 63)

FIOURE 12 Sizc

that of P. atavus; M T - ~ 16 mm.; Ms one-rooted, vestigial; jnw shallow.

LIMNOCYON Marsh 1872 (A, 126)

Dentition, v, f , +, 4. M$ absent; ME transverse, with mctaconc vestigial and parastyle elongate; ML with protocone reduced slightly; Pz two-rooted, lacking protocone; MT somewhat smaller than Mu; trigonid of Ma narrower than long; P+ two-rooted. Jaw deep, with robust sympbysis. Skull moderately broad, with strong sagittal and occipital crests. Body and limbs fairly robust; feet spreading and plantigrade. Size moderate. -. -

Lower Eoccrc, Lost Cabin, Wind River Basin, Wyoming.

Limnocyon verw hfanh 1572 (A; 26) F I G U R E ~ 5, 7, 12, 17, ZSP, 3 f

J Middle Eocene, Lower and Upper Bridger, Bridger Basin, Wyo-

ming. Lcngth Mr-3 16.5-19 mm.; 19 present; vertical ridges on prc-

179

niolars a id tmainrs faint; rinsirls not closgatc. robust.

is B synonym. figure. 1) for illustrations of this spccics.

Limbs not ~spccially

AH shown by Wortiiinn (1902, p. 197), L. (Telt~mlocyotr) riparius See Matthew, 1909 (text-figures 53-58; pl. XLIV,

Limnocyon potens Mattltew 1'309 (447)

I-'I(;uI(Es 5, 10, 15, 28, 29

Upper Ihccnc, Washakic l3, Wnshakie Dnsin, Wyomiig; Uiiita 13, Uinta Basin, Utah. Imigth MI-I 20.5-22.5 mm.; 13 nbscnt; strong vertical ridges on canines nnd prcmolars. ~ _.

There is little doubt that L. douglassi Peterson (1919, p. 45, pl. XXXIV, figures 11-14) from thc Uinta Basin belongs to this species. I t agrees very closely in size and in othcr characters; P7 is rclativcly larger than in the type of L. polens, but this is a variable fcaturc in Limnocgon.

THINOCYON Mnnh 1872 (B, 204) Similar to Limnocyon except for thc shallow jaw, weak skull crests,

smnllcr sizc and more slender proportions, and sub-digitigrade feet. This group is very closely related to Limnocyon, and is retained as

n distinct genus only because of its sub-digitigrade, more cursorial ndaptation. Most of the differences are directly correlated with thc smaller size of Thinocyon. The species are not clearly marked because of thc large number of intermediate forms and the great variability of the characters in which they differ.

Thinocyon mustelinus Mntthew 1909 (461)

Middle Eocene, Bridger B, Bridger Basin, Wyoming. Size very small; MT-T 10-1 1 mm.; trigonid of M2 narrow; premolars simple and crowded; PT two-rooted; jnw very shallow.

Thinocyon velox Manli I872 (I), 204)

I'IOUICES 15, 17-21, 23A, 30A, 31

Middle Eocene, Bridger B, Bridger Basin, Wyoming. Sizc slightly larger than T. mustelinus; MT-T 11.5-12.5 mm.; trigonid of MT rclativcly wide; prcmolars simple and usually well spaced; PT two- rooted; jaw shallow. (Figured by Matthew 1909, text-figures 59-61, pl. XLIV, figures 24.)

Thinocyon medius (Wortman) 1902 (204, 6gures 81-82)

FIOIJltE8'5, 7, 10, 12, 24A, 25A Middlc Eocene, Upper Bridger, Bridger Basin, Wyoming. Size

Iargcst of genus; M T - ~ 13-14.5 mm.; P+ and usually P3 with well

dcvclopcd antrrior basal cusp; Pr two-rooted; jaw relativcly deeper than in the other spctcics. Thrrr arc many intcrrnediatc forrns to T. vebx.

Thinocyon cledensis Muttltcrv I009 (JW)

Midtllc Il:oct!w, Washnkic A, Washakit Basin, Wyotnitig. Sin! of T. celox; MT-H 12.5 mm.; premolars long and narrow, lacking distinct untcrior bnsal cusps; P i one-rooted'; jaw shnllow. This spc~cirs is ndvnticcd i n tho onc-rooted first prcmolnr.

OXYAENODON Muttlrcw ItcY9 (49)

Dentition, +, +, 4, f. &I2 trnnsverse nnd reduced; M' broader thaii long; P3 two-rooted, with small inner bulge, but no distinct proto- conr ; lowrr molars with reduced metaconid, and with some elon~ntion of the pnraconid-protoconid shear; lower premolars robust and simplr; I).:- two-rooted. Jaw thick and shallow, with bluntly rounded chin. Skull short and broad.

The form of the jnw and the brond skull are especially characteristic. The generic name was first used by Matthew in April 1899 (p. 49) in n list with n reference to a figured spccimcsi; it was first dcfinrd by IVortriiaii in June 1899 (p. 145).

Oxyaenodon dysodus Mnttlrcw 1899 (40)

Uppw Eoccnc, Uintn R, Uinta Basin, Utah. Length MT-T 20 nini.;

jaw Irss abruptly rounded than in 0. dyschrw. This form way first dcscribcd by Osborn in 1805 (p. 78, figure 3) a~ I ' ? IIyaenodon." I t was referred by Mntthew in 1899 (p. 49) to this genus and species.

Oryaenodon dysclerus Hny 1902 (759)

FI(IUILEB-~, 7, 10, 12, 15, 17, 27 Uppcr Eoccnc, Uintn C, Uinta Basin, Utah. Size smaller; MT-'I

18.3 mm.; chin more abruptly rounded. Originally described by Wortmnn in 1890 (p. 145, figure 3) ns 0. dysodus, but rcnnmed by Hay in 1902.

THEREUTHERIUM IWtol 1876 (289) Ilcritition, 4, +, +, %. M 2 transverse and much reduced; ML with

c4oiigstc inctastylc and reduced protoconc; PL two-rooted, Incking p$toconc; lowcr molars subcqunl, specialized for shearing; metnconid %scIF' 'protoconid nnd parnconid elongate to form shearing blndc; tnlonid reduced on Ma; lower premolars sirnplc; Pf one-rooted, small. 't Jaw thick and shallow.

This genus approaches the specialization of the advanced Oxyaeni- nae, but its relationship with the Limnocyoninae is indicated by the

l ~ ~ : A l ~ ~ ~ l ~ : ~ ~ ~ ~ ~ ~ l ~ ~ , ’ l ~ ~ ~ ~ l ~ I . 181

unreduced M.r, the arrangc!mcnt of thc lower incisors, thc two-rooted Pz lacking protocone, shallow jaw with long, slender angle, small size :uitl other characters. It may rc+groscnt 3 separate line, derived from thc Yrovivcrrinac, and parallding the Limnocyoninac.

Thereutherium thylacodes Fillid 187G (289)

l ~ l G u l l ~ : 8 5, 7, 10, 12, 15

U p l w Ihc(mv, 1’hosphoritc.s dc Qucwy, Cnylux, Escarnps (iwar

Subfamily MACHAEI~OIDINAE Matthew 1909 (330) Carnassial teeth Ma; M 3 absent; CT reduced and, by infercnce C1-

cwlarged; jaw developing ventral flange anteriorly. Thc Mnchncroidinac arc mi offshoot of thc Limnocyoninae showinfi

:I rcmiarkablc parallelism to thc true sabre-toothed cats (Machaero- tlontinae). Matthew in 1909 merely suggested the subfamily name and rctaincd Machaeroides in the Limnocyoninae, but the discovery of the more specialized genus, Apataelurus, makes the separation of t,liis group advisable.

Lalbciiquc!) and Mouillac, 1:rnncc. Size very small; MT-T 7-8 Inm.

MACHAEROIDES Mattlicw 1909 (461)

Lowvr dmtition, 2 or 3, 1, 4, 2. Lower molars with eloilgate para- c.onid-protoconid shmr nearly parallel to jaw, and reduced metaconid; talonid of M a very small; PI-7 elongate and much compressed; PT two-rooted or with roots partially united; moderatc CT-PT diastcma; Crymall; Ix large; 1.1 small; IT may bc absent; jaw thin and moderately decp, flaring laterally at canine, and lacking ventral flangc anteriorly; chin dccp, nearly vertical.

Thc jaw of Mmhaeroidcs rcscmblcs tha t of Fclis, and is not truly ‘ I sabre-tooth.”

Machaeroides eothen &fntthcw 1909 (462, figures 48, 71)

FI(IUIIER 5, 7, 13

Middle EOCCI~C, Uridger B-C, Hridger Basin, Wyoming. Lcllgth M7-2 16 mm. .The typical specimens are from Bridgckr I< . Amer. Mus. Nat. Hist. 12083 from Br idpr C is somewhat larger (M.r-5 18 mtn.) and has the two roots of 1 5 united; it may be Considered an advanced variant.

APATAELURUS Scott 1937 (455) . Lower dentition, ? 2, 1, 4, 2. MY large, with shearing blade similar

to that of Patriofelis, with vestigial talonid and no metaconid; MT much reduced, but shearing, with small metaconid and talonid; Px slender and compressed, with large, distinct anterior basal cusp;

anterior premolars very snidl ; P r one-rooted; loiig CT-l’r diasteiiia; CT very small. Jaw as in Mlachaerodus or Ilopbphotrciis, with low condyle, reduced coronoid and deep anterior ventral Hangc.

Apafaelurtts is a remarkable parallel of the truc sabre-tooth cats, and was probably derived from Machaeroidcs.

Apataelurus kayi Scott 1037 (456)

1 h U I t E S 5, 7, 13

Upper h c c n e , Uintu, B, Uinta Basin, Utah. Length Mr-2 30 1111ii.

Subfamilies PI~OVIVERRINAE Matthew and HYAENODONTINAE Matthew

These arc the long-faced, narrow-skullcd Pseudocrcodi, with carnassinls Mg. They arc not within the scope of this papcr.

NOTE ON DIDYMOCONUS AND ARDYNICTIS

A rdyniclis and Didytnoconus of the Oligocene of Mongolia wwc considered by Matthew and Granger (1924, p. 3; 1925, 0. 3) to bc spccializcd derivatives of the Oxyaenidae, largely because they hnd only two molars above and below, and possessed short, heavy jaws with stout canines and massive symphyscs. These gcncra, howcvvr, are fundamentally different from the broad-skulled Pseudocreodi in the following respects: P) are very molariform, a condition not even approached in any oxyaenid; M 1 has a small metastyle, wcll separated paracone and metacone, and develops a peculiar hypocone plnced internal as well w posterior t o the protocone; in all the broad-skulled Pseudocreodi the metastyle is elongate, the paracone and metaconc are closely appressed, and the postero-internal region of the tooth is reduced, rather than extended by the development of n hypocone. M2 is less transverse, and has n shorter parastyle and larger metaconc than in any oxyaenid or limnocyonine. MT is not reduced, as is invariably the case in the Pseudocreodi. The lower molars have a large, distinct metaconid and much reduced paraconid, whereas, the paraconid is always enlarged and the metaconid reduced even in the earliest Pseudocreodi.

From the above facts, it appears highly improbable that Didytno- conus and Ardynictis are related to the Pseudocreodi. If they are Carnivora, as the large canines and heavy jaw suggest, they are quite distinct from any known family of Creodonta or Fissipedia. It is possible that they were derived from some member of the Paleocene Triisodontinac, which approach them morc closely in tooth construction.

183

GEOLOGICAL AND GEOGRAPHICAL DISTRIBUTION

The distribution of the broad-skulled Pseudocreodi is shown in FxcunEs 3 and 4. The group is found largely in North America, and probably originated on that continent, since the earliest forms occur there. The Oxyaenidae make their first appearance in the Upper Pnleocene of Wyoming, with representatives of both subfamilies known. During the Lower Eocene, the genus Oxyaena shows a rapid evolution in western North America, and in the Middle G c e n e gives way to its descendant, Pahiofelis. The giant Sarkaslodon, the last of the Oxyaeninac, occurs in the Upper Eocene of Mongolia. It is one of many forms in the Irdin Manha formation which shows the close connection of North America and Asia in the Upper Eocene after a long period of separation.

The genus Dipsalodon of the Upper Paleoccnc of Wyoming is the cnrliest known member of the Palaeonictinae. I t is succeeded in the early Lower Eoccne by Palaeonidis, which occurs in both Europe and North America. Although the French species is perhaps more Primitive than the North Amcricnn, it migrated probably from North America during this period when the continents were closely con- nccted. In North America, Pahonicl is gavc rise to Ambloclonits and then the line died out at thc cntl of the Lower Eocene; in Europr, it is possible thnt thc subfnmily persisted until the Upper Eorenc find gnvc rise to Pnroxyaena of the Phosphorites of Qucrcy.

The Limtiocyoninnc arc mostly North American. Primitive Inem- bcrs,of the group (Prolimnocyon) appear in the Lower Eocene of Wyoming, and in the Middle Ebcene the species are more varied and numerous. This is the time that their specialized offshoots, the Machaeroidinae, make their appearance. In the Upper Eocene, the Limnoeyoninae are reduced in numbers in North America, and disap- pear before the cnd of the period. Little is known of the history of the group in Europe; it is possible thnt they never reached that continent and that Thereutherium is a separate offshoot of the Proviverrinac and the result of a parallel evolution. On the other hand, some primitive limnocyonine may have reached Europe when it was connected with North America in the Lower Eocene, and Thereulha'um may have evolved from that form during the Middle and early Upper Eocene when the two continents were srpnmted.

* I

I I - BRIRGER BASIN, hk - ~ N D RNERBASJN, WYO. WMHAKIEBASIN,,\~F~~

____

CL

E " FIOIJRE 3. Geoloe3~'gcograoographlcal cll~tribut.lon of tho broad-sWd PnoudocreocU'

(Part I) .

DEN ISON: YSE UDOCREODI 185

UNTA BASIN, UTAH MONGOLIA DUCHESNE

UIMA C 1 Orydencdon d+s

UINTA B Limnawn potens Sarnasfodm OXyne& c+Xmiu3 Apataelunu b y i

UlNTA A

1 ARSHANTV

I

)lUaenoideJ 3

AlMAGRE

L U 7.7.A N

YPRC5IAN "Lc... ,..

SPARNACIAW (CONGiOFlERAT DE M E U .

AND IlGN/TfS DU so/SSOh"ALS)

Palaecnictis gigantea

THANE TlAN

FIGURE 4. G ~ ~ l ~ g l ~ n l and peogmphlcal dhtrihution of tho hwd-skulled Psoudocmodl (Pan 11).

186 A N N A L S NEII' I'OllK A C A D E M Y OF SCIENCL5S

STRUCTURAL AND FUNCTIONAL EVOLUTION

Teeth INCISORS: (FIGURE 5.) In the ancestral creodonts, the incisors

were three in number in each jaw, and, no doubt, small and subequal in size, and arranged in a transverse row. This condition is found in Oxgaenodon. Thc lower incisors of most of the broad-skulled Pseudo- crcodi, however, are crowded greatly between the canines, nnd arc reduced in size and in number. Oxyaena g u b shows the most primitive known statc of any of the Oxyaeninae; it still retains three lower incisors arranged transversely, but IT and Is arc reduced. In later members of the subfamily, the incisors exhibit a tendency towards a more antero-posterior arrangement, which is a result of crowding, and both IT and Is mny be lost, as in Oxyaena 2tUima. Palriofelis may rctain all threc incisors (Amer. Mus. No. 12078), but the most anterior (Is) is lost in another specimen (Yale, Peabody hlus. No. 10940). Sarkaslodon has only a single lowcr incisor, probably 1.1. This reduction of the lower incisors, and their crowding between the canines can mean only a corresponding diminution of function; whcre they arc. used for nipping, as in the Miacidae and most Fissipedia, they arc plnced anterior to the canine, and nre transversely arranged.

Thc lowcr incisors of the Palaeonictinae arc not wcll known. PaZ- rreotzictis is primitive in having threc, subequnl in size; it is probable, but not ccrtnin, that they were arrangcd transversely. Ambbclonus .s-inosti~ has one of the incisors somewhat cnlarged, nntl the others rcducctl; they arc rrowdctl, 3s in the Oxyacninac.

I i i the Limiiocyoninar, only the t,hic:k-jawcd Oxyaenorlon is kiiown to hnvc t.lirw subcqrinl iiicisors, nrrangcd in a transversc row; in this ~ t m ~ s it. is prolxhly sccoiidary rathcr than primitive. All the other Limnocyoninae show crowding and displacement of the lower incisors. Instead of assuming nn antero-posterior. arrangement, ns in the Oxyaeninae, the middle incisor moves backwards, and IT and Is remain n t the front of 'the jaw in Thinocyon and Thereutheriicm. There is less .functional rcduction in this subfamily.

Apafaelurus, the sabre-tooth hyaenodontid, has lost IT, but 1z-z arc Inrgc; the much rcduccd caninc is of only slightly greater size. Although their form is not known, all the anterior teeth probably occluded well with thc upper incisors and canine, and functioned to nip and tear off flesh. Its nncestor, Machaeroides, shows some reduction of the caninc and enlargement of Is; the inner incisors arc not known, but thcrc is space enough for a small IT as well ns IT.

188 11 N N A L S iVElV YORK ACADEhlY OF SCIENCES

Sincc the upper incisors arc placed well in front of the canine, they 3rc less crowded, and retain n trsnsversc arrangement. In all thc Oxyacnidac, the inner incisors arc reduced and 13 is enlarged. Ozyaenn g d o and Pnlaeonicfis show this condition a t an early stage; they retain n small 1-I-. The typc spccimcn of OXIJU~XU intermedia has lost this tonth, and 13 is quite small. The Upper Eocene Paroxyaena is similar. The third incisor in these forms closes against the nntcro-internal side of the lower canine, and probably occludes in part with the largest lower incisor (IT); it would help to hold food, but this arrangement is not ndnptcd for nipping. The latest oxyaenid, Sarkaslodon, has lost 1' and has Id rcduccd to a vestige; 13 is a tkcmendously largc, robust tooth, wearing blunt a t thc tip. It suggests that the crushing function has cxtcnded to the most nnterior part of the jaw in this animal.

In thc Limnocyoninae, Oxyaenodon and Thereitlheriunt rctnin n very primitive arrangcmcnt of the upper incisors. In Litnnocyon 12 is enlarged and, in contrast to the O.xyaenidac, 12 is rcduccd or lost. These tecth wear very blunt, especially in Limnoqon polens.

CANINES: (FIGURES 5,8-15.) In the early Oxyncnidnc the canines are of a normal carnivorc type, and not especially robust. Both the upper and lower canines havc an internal and a posterior vertical ridge. The upper canine differs from the lower in its slighter curvature and nlso in wear. In the later members of thc family the canines become rclativcly larger and much morc robust. This is true of I'nln'ofelis and Snrkaslodon cspccinlly. I n a11 thc Oxyacnidnc, and (~spc(*ially in the later forms, thc tips of the canines rapidly wenr hlulit ant1 Iwc.omc entirely unadapted for piercing flesh; their function wns probnldy limited to holding, and to some extcnt to crushing food.

The J,imnoc.yoninnc havc less robust canines in gcnernl. They nrc cwpccinlly slender nnd piercing in Proliwtnocyon. All of thc shallow- jawed forms hnvc nn abrupt curve in thc root of the lower cnnine a$ it leaves the jaw. Thcrc is also a characteristic sharp, bnckwnrd eurvn- turc in the crown of this tooth in Linimcgon and Thereutherium, and perhaps in other genera. The upper cnninc is also more curved thnii in thc Oxyaenidae. Oxgaenodon has developed very robust canines.

The Machaeroidinae parallel the true sabre-tooth cats in reducing the lower canine. The reduction is moderate in Machaeroides. AI- though its form is not known in Apataelwus, its alveolus shows it to bc only slightly larger than the incisors, as in Hoplophoneus. In the presence of the very characteristic sabre-tooth modifications, espccially thc ventral flange on the lower jaw, it is practica1ly certain that the upper canine of Apataeltirits was an elongate, stabbing tooth such as occurs in Hoplophoneus and Machaerodus.

DENISON: PSEUIWCREODI 189

LOWER PREMOLARS: (FIGURES 6,7 , 11-15.) In the Oxyaenidae, PT, when present, is a small, simple, single-rooted and single-cusped tooth. It is absent in Oxyaena only as an individual variation, but it is invariably-absent in the later Oxyaeninac, Palriojelis and Sarkaslo- don. On thc othrr hand, it is ncvcr absent in the Limnocyoninac and Machncroitlinae, and usually has two roots and a heel cusp. This is correlated with the fact that thc jaw is never as much shortened or the tooth row ns much crowded as in the Oxyaenidae. Thereidherium, the latest and most spccialized of the Limnocyoninac, and Thinocyori cledensis are the only mcmbcrs of the subfamily to have PT reduced to a single-rooted, csonicd tooth. Machaeroides has the two roots distinct in thc Lower Rridger, partly united in the Upper Bridgcr, and the Upper C 4 ocenc Apatneluriis has only a very small, single-rooted PT. This reduction is not due to crowding as in the Oxyaenidae, but is a result of the fact that the function of the cheek teeth is largely restricted to shearing, and is thus located more posteriorly in the jaw.

Pv-7 arc two-rooted teeth, increasing somewhat in size and com- plexity postcriorly, but fundamentally similar. PT lacks a distinct anterior basal cusp, although there is always an anterior cingulum. On P3 3 separate anterior cusp appears in somc Linznoc!/on ant1 Thitwcyon, and in the advanced Oxyacninac, Palriojelis, Sarkaslodon, and a few species of Ozyaena; the other forms have only a cingulum anteriorly. The anterior cusp is always present on PT, though it is small in most primitive spccics. It is strongly clevclopc~d i n tlic Palneo~iictinac, even in the Upper Paleocene Dipsalr,(lo~i. Thwr is n progrcsivc incrcasc in its size i n Oxyaena, and it rcavhes its maximum tlcvclopmcnt in Pnlt-iojelis, but Satkaslodon has either rcclucetl it, or evolved from some oxyacninc which had not progressed far i n thc tlcvelopment of the anterior cusp. It is relatively weak and varinblc i n the Limnocyoninae. In the Mac+haeroidinac it is elon#ntc and shearing. A hccl cusp is always present; on Pf-3 it is smaller niitl

crushing; it is longer on Pr, where, with the transition to the ~nolars, its function is more shearing. Anterior and posterior cingula occur on both the external and internal sides. These are strongly developed in thr Palaeonictinae, and show a marked tendency t o develop small cuspulcs. The protoconid is always the largest cusp and is crushing in function, except perhaps in' the Machaeroidinae,, where it is more shearing. The emphasis of the shearing function in the latter group has rcsultcd in the reduction of thc anterior premolars (PT-3) which arc used ordinarily for crushing.

It is not known to bc lost in the Palaeonictinac.

190 Ah'NALS A'EIV YORK ACADEMY OF SCIENCES

I . 1 he proportions of thc premolars vary considerahly. A111011g thc: Oxyucninac, slender premolars arc found in Dipsalidiclides, Oxyaenu

Jrom .51 to .58. Other species, notably 0. aequidens and 0. forcipala, have broader premolars with thc corrchsponding ratio of .60 to .(is. I’afn’ofclis shows a great increase in robustness, and Sarkastodon goes

p l u t y p i ~ , 0. lupina and 0. ultima; in thcsc the ratio lcngtl, W l d t l l of P+ varics

irmunz 7. Lower cheek teeth of the Llmnocy+nhcC ax“ bfachnlroldlnao.

to extremes in this direction; in the latter genus, Pu and Ps are nearly as broad posteriorly as they are long, and may have the posterior root partly divided, an exceptional condition for o. carnivore. he Palaeo- nictinae have rather robust premolars, especially in the F ate% foms. On the other hand, they are generally slender in the Limnocyoninae, although in Lirrinocyon potem and Oxyaenodon they become quite robust. In the Machaeroidinae, P7 is exceptionally long and slender.

193

UPI’kIt I’HEMOLAItS: (FIGURES 8-10, 14, 15) The first upper premolar agrccs elosc.ly with the corrcqonding 1owc.r tooth, and the tltwriptioii of thc latter is equally npplicublc htw.

I t i i w w

clcvclops u distinct anterior cusp, but thcrc is alwuys a11 anti*rior cinguluin. A postcro-external cusp is prcwnt, but is quite srriull ill

the early spwies of Oxyaenu. In the Limnocyoninac thcrc is no indic:rtion of a protoconc or intcrnal cusp, but i n Palq.cunzclis and thv Oxyac*iiiuuv thcrc appears a postcro-inttLrnal swclliiig, which bccoincs quitc rnarkcd in some spccimcns of Oxyaena forcipafu, and develops into a distinct protoconc in Patriofelis and Surkastodon. Accornpany- ing this change, thc posterior root cxpnnds transvcrscly, and in the last named gcnrra n third or inncr root has scpamtcd.

.- VI:’N I+SOhr: I ’ S I:‘U IXICIIEO 1)l

1’2 is two-rootcd, cxccpt in Patriofeliu und Surkudotiori.

\ \

\ \

\

\

FJQUJW 3. Palate and upper toctlr of PnJaeodctlnae. nine olghtlis naturnl dzo .

In thc Oxyaeninnc, the primitive Pa is similar to Pg, two-rooted, nnd without n tracc of n protoconc lobc; this condition is exemplified by Dipsalidictides and Oxyaena pla lypm. In intermediate species of Omjaetm, such as 0. transiens, 0. gtdo and 0. intertnedia, the inncr root has separated or is separating, and thcrc is n srnnll internal lobel which docs not bear, however, a distinct protocoh. In 0. lupina and 0. forn’pata this protocone lobc is large and has a distinct cusp. I’alrio- felis nnd Sarkastodon arc advanced further in the large size of thc protocone. In the Palaeonictinae, Palaeonictis has an inncr lobc bearing variable small cuspules, one or several of which may be homologous with the protocone. The Limnocyoninae differ markedly ill

that the most primitive genus, Prolimriocyon, has .a three-rooted P3,

IIBNISON: I’~Sh’ULK)CHBOUI 195

whilc most of the later genera have this tooth simple and two-rooted, IIPVW with a distinct protoconc. In the nearly related Proviverrinae, Sinopa lacks the internal root but may have an internal swelling, which is lacking in advanced species and genera of this group. This suggests a nimplifiration, which is apparently what has taken place in the Lininocyoninae. Moreover, an investigation of the early Paleo- cenc Creodonta reveals that the protocone is almost always present on P3, thus its presence is a primitive character, and i t was probably present in thc ancestors of the Proviverrinae and Limnocyoninae. On thc other hand, there is every indication that the immediate ancestors of thc Oxyaeninac did not possess a protocone; this may mean that they had never developed it, or possibly that they had lost it early. The presencc of thc internal root on Pz of Ozyaenodon may be a retention of a primitivc character, but the evidence is inconclusive.

P‘ always has a largo internal root and a well developed protoconc. In all the Limnocyoninae except Theteutherium the protocone ia a simple conical cusp, but in the Oxyaeninae the protocone develops nnterior and posterior ridges or cingula which increase in size and, in ndvanced Oayaena and Palriofelis, give a more basined character to the inner lobe of PA. This basin forms a more efficient crushing ap- paratus than thc simple, conical protocone, and its posterior edgc extends the surface against which the paraconid of MT shears. Ther- eulherium approaches the oxyaenine type in this respect. Palmonictis lias the anterior and posterior cingula well developed. Pk differs also from P2-S in the presence of a n anterior cusp or paraatyle. The postero-external cusp, or metastyle, is usually elongate, and forms the external part of the shearing surface for the paraconid and protoconid of MT. It is shortest in Palmonictis, in which the shearing function is least emphasized.

LOWER MOLARS: (FIGURES 6-7, 11-15.) Among the broad- skulled Pseudocreodi, MS is retained only in Yrolimnocyon, where it is much reduced or vestigial. It is largest in P. robuatua, in which all of the essential elements are present. In P. &us it S much smaller and variable; the two roots may be separate or united; only a single talonid cusp remains, and the metaconid may be lost. In P. anliquus it is very small and single-rooted. This genus emphaaizes the close relationship of the Limnocyoninae and Proviverrinae. In the contemporary Sinopa, a member of the latter subfamily, Ma is usually the largest of the lower molars, but in S. mordax, and to a lesser degree in S. stetnua, MS is reduced.

In all the most primitive members of this group, MT and M s arc

similar and subequal, tuberculo-sectorial, .with thc paraconid only slightly larger than the mctaconid, and with the talonid unreducctl.

1 1 1 t h : Osyac.tiiirur, starting from this point, MY is cnlargcd aid MT rc:duccd, and thc 1)traconid-protoconid shearing blades of both teeth are enlarged, cspccially that of Mu. Thus the latter tooth is dcsig- natcd as the carnnssial. The transformation of a tubcrculo-sectorial M.2 into a sectorial tooth involves the reduction and loss of the meta- wnid and talonid, the elongntion of thc? paraconid nnd protoconid, :wid tlic rotation of the shearing surface until it parallels the axis of the jaw. This evolution is cxpresscd numerically for Mg in TABLE 1.

Slwcics

I 1.00 .98 .8D

.90-.'31 .84

.77-. 86

.86-. 87

.82

.81

-

1 . 0 9 1.05 1.02

.9l-. 97

.91-. 97

.77-. 85

.75- I 79 .57 .41 .48

L. t n l d

L. toot11

.42

.39

.35 .36-. 30 : 33-. 37 .28-. 34 .28-. 33

.16 0

.02

Shear anglc

GO" 60" 50"

40" -45" 40" -45" . 30" -35"' 30" -35" very low

0" 0"

'I'AULC 1. Nuiiicrlcrl uxprwlon of tho ovolutlon of M, in tho Oxyaonidnc.

Thc talonid of iMg differs from thnt of MT in having thc cusps less distinct, and usually forming a nearly continuous ridge. In Pdrio- jclis and Sarkastodon the talonid is minute, or represented only by a short cingulurn.

Although MT undergoes the same changes as M P , it lags far behind the lpttcr tooth, and never bccomes n true sectorial. In Osgaena and Prolopsalis the hypoconid, hypoconulid and entoconid are moderately distinct, and the hcel is bnsined; but in Palnbfelis the talonid becomes shearing by the reduction of the cntoconid and the development of the hypoconid into a median, antero-posterior ridge. The trigonid of &IT, especially the paraconid and protoconid, become elongate and more shearing in thc later Oxyaeninae, but a small metaconid is always retained.

The lower molars of the carlicst of the Palaeonictinae, Dipsalodon, arc very close to those of primitive species of Ozyaena, but MY is very slightly smaller than Mi-f%j%f~ 1.05). This genus helps to connect the two subfamilies in tooth structure. In Palaeonictis the reduction of MT has gone much further ( h i ~ / M g 1.15-1.43).

Both molars arc cssc*ntially tubrrt:ulo-scctorial. Thv paraconid-protoconid shear is slightly enlarged and has a characteristic outward convexity; the metaconid is only slightly reduced 01) MT, but is variable on MT where it may be vestigial. A characteristic featurc of thv Palaeonictinae is the distinctness and large size of the talonid cusps of MT; on Mu only the hypoconid and entoconid are present, and they may be quite indistinct. In Ambloclonus, IMT is essentially similar except that its trigonid has a more crescentic form. MY is morc specialized in that the metaconid is completely absent, and the talonid is much reduced or vestigial. The paraconid and protoconid form a shearing blade which is strongly convex outward. Although much smaller and less efficient as a sectorial than the corersponding tooth of the Oxyaeninae, it is nevertheless the carnassial.

Mr-5 of the Limnocyoninae arc much less progrctssive than thow of the Oxyaenidae. In Prolimnocyon they are of a primitive tuberculo-sectorial typc, with unreduced metaconids and relatively long talonids. Limnomjon and Thinocyon are advanced ,only in the simplification of the talonids and slight elongation of the paraconid- protoconid shears and reduction of the metaconids. The Upper Eocciw Ozyaenodon carries these tendencies a bit farther, and has the talonid of Mv somewhat reduced. Thereuthmiutn is the most specialized member of the group; it haa lost the metaconid completely, and has a well developed paraconid-protoconid shear, nearly paralleling the jaw axis, but the talonids are reduced very little. An important difference between the Limnocyoninae and Oxyaenidae is that MT is reduced only slightly in the former.

In the Machaeroidinae, the sectorial specialization is much morc extreme than in any of the Limnocyoninae. The lower molars of Apataelurus parallel those of Palriofel+ so closely that a near relationship is strongly suggested. But Machae?oides, a n undoubted offshoot of the Limnocyoninae, shows many advances in the direction of Apataelurus and serves to connect the latter genus with the Limno- cyoninae. Machaeroides has very slender, sectorial molars in which the talonids are still large; but the metaconid is much reduced on MT and may be absent on MT.

A small M” is prvscnt in Prolimnocyon atavus, indicated by two alveoli in h e r . Mus. No. 15171. In the other broad-skulled Pseudocreodi, ME is absent. . In all the members of this group, M I is transversely placed, vestigial or absent. This condition contrasts with the long-faced Pseudocreocli, Provivcrrinae and Hyaenodontinae, in which M I is the main upper

UPPER MOLARS: (FIGU~EEI 8-10, 14, 15.)

carnassial. In the intermediate form, Prolimnocyon, it is least reduced; its postero-external corner is moderately prominent and the metacone is distinct. In later Limnocyoninae the metacone is vestigial or &sent, but Mg is always present since it occludes with the talonid of M q which is relatively unreduced in this subfamily. In the Oxyaeninae, M E is present in Ozyaena which retains a talonid on Mv, and absent in Pahiofelis and Sarkasbdon in which the talonid is lost. When present, the metaconc is indistinct. In both the Limno- cyoninac and Oxyaeninae M I has three roots, one external, one internal and a small posterior one. In Pulaeoniclis M I is variable. In Amer. Mus. No. 16960 i t has three roots; in No. 16116 it is a very slender, transverse, two-rooted tooth, lacking a metacone; in No. 110 it i8 a smd1, round, single-rooted vestige. A small Mg is present apparently in Ambloctonu8 sinosus, but it may be lacking in A. hyaenoides which has nearly lost the talonid of MT.

The primitive ML of the Limnocyoninae and Oxyaeninae has the paracone and metacone partly connate, a moderately long metastyle and a short parastyle, large protocone, and small protoconule and metaconule. In the earliest oxyaenine, Dipsalidiclides, ML is much wider transverAely than long due to the exceptionally well developed protocone and small metastyle. It is possible but not certain that this is the primitivc condition for the group. In the other Oxyaeninae

. the metastylr is progressively elongate and the protocone reduced. This brings about a lengthening of the shearing surface and a rotation of this surfaw until it becomes nearly pnrallel to thc cheek tooth-row, thus forming n inore cffective sectorial. The culmination of this cwdution is found in Pdriofelin and Sarkastodon, in which the proto- c o i i ~ is vestigial and the shearing blade is very long and made up half by thc metastylr and hnlf by the conjoined paracone and metacone. In the Limnocyoninae, the metastyle,j: never as much elongate nor the protocone as much reduced, and ML retains a distinctly tritubercular appearance.' The 6rst molgr oE the Palaeonictinae has quite a different appearance, largely due to the fact that the metastyle is quite short and the paracone and, metacone are less closely conjoined. But as Matthew pointed out (1909, p. 411), this tooth is the carnassial, although its sectorial function i6:not emphasized as much 89 in the -0xyaeninae. Its antero-external; angle is very short, not lengthened m in those forms which have a catnassial Pk.

MILK DENTITION: .The to th succession of the broad-skulled

lower milk teeth of Ozyaem are well known from several individuals. Pseudocreodi agrees well wi th th P t of the h ipedes . Both upper and

200 A N N A L S iVEW YOllK ACADEib!Y OF SCIENCES

The'lower milk molars of Palriojelis were considered to be a distinct genus, Aelurofhen.u?n, until Matthew showcd their correct affinity (1 909, p. 4 19) ; his conclusions are confirmed by a spccimcn in the U. S. National Museum (No. 13318) bearing DPy-+ and MT erupting. Some of thc milk dentition is known in Palaeonictis and Ambloctonus, and it is thoroughly described in Thereuthmiuni by Martin (1906, p. 592). As is usually the casc, each milk tooth agrees closely with the permanent tooth just behind the onc which succccds i t ; for example, DP' resembles M-l-. The milk teeth are usually smnllcr and of more slender proportions. The tooth between DPs and DCT is probably PT; in any case, there is no evidence thnt it has 3 succcssor.

Lower Jaw The lowcr jaw (FIGUREG 11-15) is usually one of the most numerous

and best preserved of fossil remains and as such is more susceptible to pxact measurement and proportional study. Four ratios are found to hc cspecially significant: (1) Depth ratio; inside dcpth. of lowcr jaw st anterior root of Mp divided by length of jaw, condylc to chin. (2) Dcntal ratio; length of lower chcck tooth row divitlcd by length of jaw. (3) Condyle ratio; transverse width of condylc dividcd by length of jaw. (4) Thickncss ratio; thickncss of jaw a t M H divided by dcpth of jaw at Mg.

spccics Dcpth rntio

.208

.237

.201 ,245 .271 .237 ,241 .I76 .I35 .1m .210 .I87 .I65 .I71

Dcntnl rat in

,475 ,470 .44x . :No .527 ,419 ,428 .50 .548 : 508 .451 .460 ,520 ,403

T A n m 2. Jaw ratlos of the bmad-skulled Pseudocteodl.

Conrlylc ruth

. In

.25

. %8

.In

.20

. I 4 -

.I5

.10

.19

. I 6

.20

~-

-

-

-

'1'1 1 i c k n csq rntio

. :I8 ,R7 . no .40

.34

.30

.52

.57

.50

.47

.58

.64

.49

-

In TABLE 2 it is shown that the jaw is relativcly deep in the Oxyac- ninne and Palaeonictinae, and becomes relatively deeper in advanccd

forms. Bemuse of the great dcpth, thc jaw is relatively thinner than in the Limnocyoninae, but i t i s still quite robust in most forms. The check tooth-row is short in the Oxyncnidne. Thc depth nnd dent.nl

202 A h'hl.4 12S N E W YOllK ACA D6 I1 Y OF SCIEA'CE.V

ratios are dependent on and correlated with the shortening of the jaw as a whole. This is extreme in Patrisfelis, Sarkastodon and Ambloctonus. The jaw of the Limnocyoninae is relatively long, shallow and thick, with a moderate to long tooth row. Only Limnocyon approaches the Oxyaenidae in j aw proportions, while Prolimnocyon, Thinocyon and Thereutherium are at the other extreme. Oxyaenodon has a peculiarly thick, robust jaw. The Maehneroidinae differ in having a relatively long jaw but short tooth-row. For its moderate depth, the jaw is thin.

I -'. ,' ,': I flachaeroi&s &hen :'

'. I' _ - Vtawar. 13. Loternal vlew of lowor Jaw of tlio MarlucemlOlnor. t w n LlilrdH nucurnl nlar

The robust symphysis is spoken of often as being characteristic of the Oxyaenidae, although it abo occurs in the Mesonychidae and 'Msodontinae. The Limnocyoninae are transitional t o the more typical Hyaenodontidae in this respect. Ih the shallow-jawed forms, Prolimnocyon, Thimcyon and Thereutherium, the symphysis is long, shallow and inclined only slightly, and the front of the jaw slopes up very gradually; it does not differ very strongly from the symphysis of certain species of Sinopa. In Limnocyon the symphysis is deeper and more steeply inclined. In Oxyaenodon it ie fairly strong, but horizontally placed, and follows the peculiar abrupt curvature' of the jaw anteriorly. The Machaeroidinae have a different specialization; this involves steepening of the anterior face of the jaw until it is almost vertical, and deepening of the symphysis. In Apatmlurw the aymphy- sis is extended onto the ventral flange which protects the upper canine.

In the earliest and most primitive Oxyaenidne, Oxyaena pZatypus and Dipsalodon, the symphysis is stronger than in the heaviest-jawed

Limnocyonine. Moreover, it increases in relative size and in inclina- tion in later forms until, in Palriofelis and Satkartodon, it forms n

204 A N N A L S NEW YORK ACADEdl Y 01.’ SCIENCES

FraoRE 15. Latam1 view of tho skull nnd jaw of the Llmnocyonlnna: Thrrcfrthcrlfrm hour thlrds natural alzo: othere two thlrde natural dze.


tremendously solid jaw attachment. Accompanying this change, the anterior face of the jaw becomes much steeper.

Ordinarily there are two mental foramina on the outer side of the jaw, an anterior placed under Pr or P P , and a postcrior under P3 or PT. In Patn'ofelis they are commonly subdivided into a number of small foramina. Extra foramina occasionally occur in other forms. Thr position of the foramina is variable and is of littlc systematic importance, cxccpt in the hiachaeroidinae in which both foramina arr placed very low in the jaw.

The above table shows that the condylc is narrow in the long, shallow, weak-jawed Limnocyoninae, and is much wider in the more robust-jawed Oxyacnidae, cspccially in Palriofelis, Sarkaslodon and Atnbloctonus. The wide condyle furnishes 3 stronger hinge. In correlation with the presence of a preglenoid crest in the Oxyaenidac, thc articular surface of the condyle extcnds dorsally onto the anterior surface; it is less extensive in the Hyaenodontidae where the preglenoid crcst is absent. The condyle is usually placed at about the height of thc check tooth-row, as in the case of carnivores gcncrally. This facilitatrs shearing by allowing the posterior carnassial tceth to comc into action first. In the Machaeroidinae the condyle is exceptionally low, as in the trur sabre-tooth cats; this makes possiblc a much wider gape.

In thc Oxyaeninae it is very short, projects only slightly, and is deep and bluntly rounded. In the Palaeonictinae it projects behind the condyle, but is bluntly rounded as in the Oxyaeninae. In thc Limno- ryoninac, the angle is long, slender, and slightly upcurvcd and pointcd at the tip; therc is an inner shelf below thc insertion area of thc . ptcrygoid muscles which gives it a slightly inflected appearance, especially in Thinocyon. Apataelurw has reduced and blunted the angle to allow a wider gape.

The coronoid process is strongly developed in all the broad-skulled Pseudocreodi except the Machaeroidinae. In Apataelurus it is ex- trcmely low, as in the true sabre-tooth cats. As Matthew has demon- strated (1910, p. 208 and 303), this allows the lower jaw to be opened much wider because of the greater length of the temporal muscle and its correspondingly great stretching range.

Another peculiar character of the Machaeroidinae is the lateral flare at the anterior end of the jaw, and the flat anterior face of the jaw. The increased width anteriorly enables the much reduced lower canine to move forward and to become functionally part of the incisor series .

T h r angular process is of considerable systematic importance.

206 A N N A L S NEW YORK ACADEMY OF SCIENCE8S

Oxyaenn

Fionnr. 10. Doml vlew of akull of tho Oxyaerildao. ono thlrd narurnl dzc.

Skull

PKOPOKTIONS: I t is not possible to iliakc as rxact a proportional ;uialysis of the skull as of thc lower jaw because the material is less abundant and usually (+rushed or fragmentary. The few Ineasurc*- rncnts given are from thc. better presvrvcd skulls and from the carc- fully made restorations. Although they give a general idea of thc skull proportions, thcby cannot be relied upon to be absolutely correct. The following measure.ments arc takcn as in Osborn, 1912 (pp. 85- 86): basilar length, from median incisive border to anterior edge of foramen magnum; frontal width, or width at posterior border of orbits; facial length, from median incisivc border to iniddlc of linc c.onnccting posterior borders of orbits; length of upper molar-prc- molar series; also takrn was the greatest width of the skull which is at th(1 posterior part of the zygomatic arch. T h v following ratios arc significant: cephalic index (frontal width X 100 + basilar length); jacio-cephalic index (facial length X 100 + basilar length); dental index (length of upper molar-premolar series X 100 i basilar length); and, zygomatic index (greatest width X 100 t basilar length).

Cephalic index

43 51 49 50 60 58 63

Specics _ _

Sinopa grangcri 'I'hinonjon velox Limnocuon vcrus L. p O h . 3 O~yaenodm dysrkrus Ozyana (restoration) Patriojelti jmoz

Fncio-ceplid- Dentnl ic index index

51 4 1 51 36 47 35 48 34 54 35 49 35 42 28

~ - ~ _ _ _ _ Zygometic

jndex

52 58 61 61 70 66 so

' ~ A M L E a. lndexcs uhowing gcneral akull yroportlons.

The cephalic and zygomatic indexes show thc relative. breadth or brachycephaly. Sarkastodon, for which figures arc not obtainable, and Patriofelis have excessively broad skulls with widely expanded zygomatic archcs, while their ancestor, Ozyaaa, is less brachycephalic, but still more so than most of the Lirnnocyoninae. Palaeonictis probably has a skull as broad or broader than that of Ozyaenu. Ox- yaenodon, one of the latest and most specialized of the Limnocyoninac, is comparable to the Oxyaeninae in its brachycephaly, but the other members of the subfamily a re intermediate to the narrow-skulled Sinopa in skull proportions. Prolimnocyon is undoubtedly the least ' brachycephalic of the group.

/- /,---._.I.

The facio-cephalic index is II measure of the relative length of t h e facial region. All of the Limnocyoninae, even the broad-skulled

Oxyueiiodoi~, liavc L moderately long facial region as i n other Ilyactio- tlontidae. In early Oxyaeninac the face is also riiodcratcly long, but it is greatly shortened in Palriofelis and Sarkuulodon. In the Lower Ihocenc Palaeonictis the facial region is precociously short.

The shortciiing of the upper cheek tooth-row is closely corrclatcd with thc shortening of the face. In Prolimnocyoti, which retains MZ, thv relative length of the tooth-row is comparable to that of Sinopa. 'I'hc other Lininocyoninae and Ozyaena have thc tooth-row shortened hy the loss of MZ, while Patriofelis and Sarkaslodon, lacking both M2-9 and P'have nn extremely reduced cheek tooth-row.

FACIAL REGION: FIGURE^ 14-17.) In thc Limnocyoninnc the maxillary bones are long and shallow and the nasals arc relatively iiarrow. In the short-, broad-faced Oxyaenidae the mnxillaries arc deepened and shortened, and the nasals arc shortened and widened. The nasals are wide anteriorly, constricted a t the middle of their length, and wide again at the maxillo-frontal suture; from herc they taper to a pointed posterior termination, which is well in front of the postorbital process in most Limnocyoninae, and opposite or behind this proccss in Linrnocyon polens and the Oxyaenidae. The form of thc nasals is similar in the Marsupialia, Hyaenodontidac, Mcsonychi- d:ic and mnny of the Arctocyonidac; it is widely different from the iincoiistrictcd, bluntly terminated nasals of DeUalherium aid the Miacidac. The anterior ends of thc nasals arc notched in the Limno- cyoninae; the extremely broad nasals of Sarkaslodon terminate bluntly aiitcriorly. The anterior opening of the infraorbitnl canal in the maxillary is over Ps, a constant feature in the Carnivora. As in all primitive mammals, the lachrymal has a rather large facial extent; this is probably somewhat reduced in Palmonictis.

PALATAL REGION: (FicunEs 8-10,) The palate of Ozyaenodon and the later Oxyaenidae is shortened and broadened along with the face. In Sarkastodon and Patriofelis it is too short to include all of the much reduced cheek tooth-row, for the posterior part of M A extends onto the zygomatic arch. The relative length of the palate in Pro- linmocyon, as estimnted from the length of the lower jaw, is greater than in other members of this group, and approaches Sitiopa in this, as in other rcspects. The earlier Oxyaenidae and the other Limno- cyoninac are intermediate in proportions. The palate is pierced anteriorly by thc anterior palatal foramina, and posteriorly in the

. palstine bone by a variable number of small posterior palatal foramina, as in all Carnivora. Along the median line, the posterior termination of the pallrtc is variable in position, in front of M I in Oxyaena, bchind

R.1’ i n I’atriojelis and Sarkaslodou, slightly behind iM3 in Thinocyou, while in Limiocyon polens and Oxyne~odotr it is far behind the posterior c.nd of the cheek tooth-row. The posterior extension of the hard ~wlatc, as in the latter two ’forms, is not unusual among Carnivora, but its functional significancc, if any, is not known. At or near thc posterior ciid of thc palate is a swollen ridgc such as occurs also in the Hyaenodontidac and inany Arctocyonidac, but is absent in thc M iacidae.

A primitivc feature of the creodonts, exhibited by most Eocene mammals, is thc shortness of the frontals, extending back no farther than the point whcrc the supraorbital crests mcet. In contrast to the Fissipedia, i n

ORBITO-TEMPORAL REGION : ( F I C U R E ~ 14-18.)

_ I + ’

1

Piounr 18. Orliital region of Thfnoryon wlor; restored from Amor. hius. No. 13081. C W l C c nataral dm.

which thc frontals arc longer and the brain is larger, thcsc boiirs cover only the olfactory bulbs, and in large forms, such aa Pahiofelis, where thc brain is relatively small, they may not cover the brain a t all. Frontal sinuses are prcsent in all except thc smallest forms, but arc simple. The Limnocyoninac havc small, slightly projecting postorbital processes on thc frontals, but in the Oxyaenidae they arc much reduced, blunted, and do not project at all. The supraorbital or temporal crests are on the dorsal surface of the skull in the Limnocyoninae, but in the Oxyaenidac they form the edge between thc dorsal and lateral surfaces. The anterior edge of the orbit is above the posterior part of P+ in most of this group; in the very short-faced Pahiofelis, Sarkaslo- a h and Pulaeonictis it is slightly farther forward. The &bit ‘is placed more posteriorly in the long-faced carnivores, such as $he Mesonychidac.

The lateral surface of the orbito-temporal region is most completely known in Thiitocyon (FIWJRE 18) and Ozyaenodoti. The resemblance of these forms to Sinopa is very close, and no important differences were observed in the Oxyaenidae. The arrangement is wentially that of the fisuipedcs, but there are some minor differences. In Thinocyon thc lachrymal is more extensive in the orbit, as well as 0 1 1

thc faw ; the frontal sends a lobe, lacking in the Fisuipedia, betweeir

mastbid p w ~ l s

13oune: 19. Ocdpltal \'low of akull. A. Palrfofelis fcrox, Amor. Mus. Xo. 1607. t h o clglithn natural slzo. B. Thinmuon odor. Amer. Mua. No. 13081. twice natarrl dze.

thr lachrymal and palatine; the alisphenoid-parietal suture is Ioiig, whereas it is short in the fissipedes due to the greater extent of the frontal bone; tht. pterygoid is larger. Of course, the less expanded cranium of tho Creodonta gives a different configuration to this region.

The great extent of the parietals appears to be a primitive character, for it occurs generally in the Creodonta. These bones extend from the occipital crest anteriorly to the interorbital conatriction, and laterally well down on the side of the cranium, and cover most of the brain. I n thc fissiprdrs thcac bonrs ate relatively smaller and part of their

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robustiless of thc aniiiial and with thc rclativc size of the brain, which is very small i n the larger animals, and largc in the smaller forms. Thc supraoccipitals extend onto thc dorsal surface of the skull. In front of ihern, in the parietals, somc forms show onc or two post- parietal foramina.

The rygomatit: arch, a5 thv place of origin of thc massctw muscle, gives a clear indication of the power of the jaw. In thr slcncler-jawed Thinocyon the zygoriiatic arch iy exceedingly thin and wcak, while in Limnocyon and cspccially Ozyaenodon it is somrwhat dccpcr and more robust, indicating greatcr crushing power, a5 the heavier jaw would imply. In Oxyaena platypus the zygomatic arch is weak, but in advanced species of Oxyaena and in Palaeoniclis i t is robust and dcepcncd, wpecially in the posterior or squamosal part. The heaviest zygomatic arches arc found in Pahiofelis and Sarkastodon, which must have had extremely powerful j a m action. The abrupt decpcning in thc squamosal part is quite characteristic of the Oxyaenidae and does not occur in the Limnocyoninae. The grcatly bowcd-out zygomatic arch of Patriofelis allows room for a largc and powerful temporal musclc.

BASICRANIAL REGION: (FIGURE 20.) Thc basicranis] region of Iinrnocyon and Thinocyon has been described in detail by Matthew (1909, p. 435 and 451), who showed the essential similarity with the l%sipedia and other Creodonta, and the primitive character as indicated by thc absence of a completely ossified auditory bulls and thc probable presence of both external and internal branches of the intcrnal carotid artery. Howover, as van der Klaauw pointed out (1931, p. 17), in its primitive s ta te the auditory bulls is loosely attached to the skull, and its abseiice may mean only that it has not becn preserved. A horizontally placed annulus tympanicus, incomplctc laterally, is prrsent in Omjaenodon (Carn. M u d No. 3051) and a fragment of it is prcserved in one specimen of Thinocyon (Amer. Mus. No. 12631); it is probable that i t occurred in most creodonts, but since it is looscly attached, has becn prescrvcd only rarely.

The form of the petrosal prornincnce is pear-shapcd, tapering nirtr~iorly in thc Limnocyoninac. In Oxyaenodon it is crested vcntrally where it meets the tympanic ring. It is unknown in the Oxyac- nidsc.

The facial ncrvc Icavcs thr skull of thc 1,imnocyoninac througli the foramen stylomastoideum prirnitivum. This is bounded anteriorly by a small process .extending from the base of the mastoid process to the petrosal eminence. Matthew (1909, p. 451) considered this to be a spur of the post-tympanic process of the squamosal, but it appears to

be a part of the petrosal, suturally separated from the squamosal. As van der Klaauw suggests (1931, p. 172), this may represent the tympanohyal which usually bounds thc stylomaatoid foramen antc- riorly. On the ventral surface, between the paroccipital and mastoid processes of Palriofelis is a groove, starting at the position of the

m d h ob)owda - - - - - FIOURE 21. B n l n of Thinc~von ~ c l o z . mstomd from Amer. MUE. No. 12631. threo h l v m

o;rtural fd7.e.

primitive styloma9toid foramen of Thinocyoti. This groovc may represent the “stylomastoid canal” or thc external part of the aquae- ductus Fallopii. If this is true, an ossified auditory bulls, waa present probably in Patriofelis, and the facial nerve left the skull through a foramen stylomastoideum definitivum. In this respect Pdriojelis is more ndvanced than any of the Limnocyoninae. 0xyaen.u agrees with Patriojelis in the presence of thc “stylomastoid canal.”

The paroccipital process of -the Limnocyoninae is flat, spatulate, and backwardly directed as in Sinopa. I t is slender in Thinocyon and slightly heavier in Limnocyon and Oxyaenodon. In the Oxyaenidae it is more robust and downwardly directed.

A post-glenoid process is present invariably in the Creodonta. The Oxyaenidae have a preglenoid crest, as do the Mesonychidae and l’riigodontinac. All the other rreodonts, including the Limnocyoninae lack this crest. This is an important distinction between the two groups of broad-skulled Pseudocreodi.

T h e structure of the basicranial region of Prolimnocyon, which has iievrr been described, is shown in part in Amer. Mus. No. 15171. It ngrres very closely with that of Thinocyon and Sinopa, differing from the former only in the smaller post-glenoid foramen, the presence of n small ~ ~ b s q u a m o s a l (?) foramen lateral to the postglenoid foramen, :ind in the less robust mastoid process.

OCCIPITAL REGION: (E’IGIJRE 19.) The shape of the occipital region varies greatly within this group. I n small forms, such as Thinocyon, the brain is relatively large, and there is ample space for muscle attachment without the development of sagittal and occipital crests. On the other hand, strong crests are needed to extend the area for muscle insertions in large and powerful forms such as Pdrio- /elis, which have relatively small brains.

T h e petrosal bone has n small extent on the occipital surface above the mastoid process. Its dorsal part extends into a fossa, at the hottom of which is the mastoid foramen for a vein. The fossa and foramen are present generally in creodonts, nnd usually absent in tissipedes, where the expansion of the brain has filled out this space.

The brain, whosr form is best known in Thinocyon velox (Amer. Mus. No. 12631), is of the same primitivr typp exhibited by all the Eocene creodonts. The olfactory lobes are very large, placed high, and entirely uncoverrd by the cerebrum. They indicate a predominance of the olfactory sense, which is reduced to II greater or lesser degree in all the fissipedes. These lobes are covered by the frontals in Thinocyon. The cerebral hemispheres, which are relatively small and simple, are pear-shaped, or slightly wider posteriorly than anteriorly. They cover the mid-brain region only partly, and show no tendency to override the olfactory lobes. The convolu- tions, moderately complex in the later fissipedes, are extremely simple here; dorsally, on either side of the median superior longitudinal fissure, there is only a sulcus lateralis; a more lateral groove may represent a rhinal ‘firnure. The cerebral hemispheres are covered en-

13RAIN: (FIGURE 21.)

216 A N N A L S NEW YORK ACAI)E,llY OF SCIENC'E.9

tirely by the parietals in all the members of this group; ccrtain of thc Miacidae show a n advance towards the Fissipedia in that the hemispheres project somewhat under the frontals.

The mid-brain region is not clear. That it is partly exposcd, and not completely overridden by the cerebral hemispheres, is a vcry primitive character. The cerebellum, which in latcr fissipedcs is partly covered by the cerebrum, is entirely exposed, as in a11 the Eocene carnivorcs.

Thc cranial cavity of PalriojeEis is shown partly in Amer. Mus. No. 1507. Since this is a much larger animal, the brain is relatively smaller, and the olfactory lobes arc partly covered by the parietals. Moreover, the roofing bones, which are very thin in Thinocyon, are cxtremcly thick in this genus. Although Wortman (1894, p. 134) states there is no tentorium, there appears to bc a thick one separating the cerebrum and cerebellum. The structurc of the brain is cssentially similar to that of Thinocyon.

Vertebrae CERVICALS: The coursc of thc vertebral artery on the atlas ap-

pears to be a fundamental character, indicative of family or superfamily relationships. In the Pscudocreodi and Mesonychidac, this artery passes around the anterior end of the transverse process in a very shallow groove. In the Canidae, Felidae, Procyonidac and Miacis (Miacidne) this groove is deep, whilo in the Ur&dac, Musteli- dae, Vivcrridae, Hyaenidac and Ooa'ecles (Miacidat?) ,it is bridged ovw. to form a foramen. Thc formation of the deeper groove or fornmm is correlated with thc widening antcro-posteriorly of the trnilsvcwa process, which is narrow in the Psc?udocrrodi.

'I'h spine of the axis extends anteriorly over the atlas, and has aleo a more slender poeteriorly directed process. The spine is sinall or absent on the third cervical, but beginning with the fourth, thc spines increase in height posteriorly. Spines ,are higher and more robust in the heavy-skullcd Patriofelis, intermediate in Limnocyon and Oxyaena, and somewhat weaker in Thinoojon. The transverse processes of the anterior cervicals are simple, but thosc of the fifth and sixth, and probable the fourth also, are divided into superior and inferior Iamal- h e , while the seventh retains only the superior lamella, nnd lacks the vertebrarterial canal.

The adaptation of the cervicals, as judged by general form apd development of .processes, agrees most closely with Procyon and Nastra among modern carnivorcs.

The posterior six cervicals are of the usual carnivore type.


THORACI-LUMBARS: Although individual variations arc not uncommon, the number of thoraci-lumbar vertebrae in fissipcdes is gcncrally twenty, and this is probably the usual number in thc Crco- donta. Zn the Oxyacnidae, Oxyaena is known to have twenty, whilc in the Hynenodotidae, Sinopu, Trilemnodon and IIyaetwdon have the snmc number. Other Pscudocreodi havc this region incompletely known. The majority of the Fissipedia havc thirteen thoracics and seven lumbars, but formulas of 14-6, 15-5, and occasionally 16-4 ocwr. A thoraci-lumbar formula of 13-7 is probably primitive in thc Creodonta; it is found in Sinopa and Oxyaena. More specializcd gcncra m-ay-have thc lumbar region rcduccd ; Patriojelis and Tritemno- don have six, and Limnocyon potens only five lumbar vertebrae. Since thr lumbar region is the most flexible part of the back, a rcduction in the numbcr of lumbar vertebrae would menn that the range of motion of the backbone wns correspondingly reduced. In confirmation of this, it nppcars that most of thc cursorial and bounding fissipedcs, which bcnd the back greatly in rapid locomotion, hnvc a long lumbar region with seven vcrtcbrac, whilc thc stiff-backed, ambulatory typcs i~sunlly havc only fivc or six lumbars.

Near thc middlc of the thoraci-lumbar series is the anticlihal vcrtebra. I ts position varies slightly, but is usually the elcvcnth thoracic, as i t is in Onjaena, Sinopa, Ttikmnodon, and probably in Patriojelis and Palaeonictis. Limnocyon potens agrees with certain of thc more hcavy-bodied, ambulatory Fissipedia in having thc twelfth thoracic anticlinal; its more postcrior position is corrclated with thc shortening of thc lumbar rcgion. Thc anticlinal vcrtcbra is a point of change in the direction of forces. Anterior to i t thc main pull oii fhc nroral-spines is from the direction of the head, thrw ttic spines lenn backward; posterior to i t thc main stress'is from the op- positc direction and the spines lean forward, The anticlinal spine is lower than the others and is vertical. The highest spines arc in the anterior thorscic region, sincc herc attaches the lignmentum nuchae, which hclps to support the head. Thesc spines are gencrnlly higher and stronger in the Creodonta than in the Fissipedia, since the head is rcl~tivcly larger in the former. They are especially strong in the heavy-headed Patriojelis. In the broad-skulled Pscudocreodi, the lumbar spines are relatively low and robust, often expanded at thc top, cspccially so in Patriojelis and Limnocyon potens. I n this they ngrec with the more heavy-bodied ambulatory hsipcdes, such as 11.1 eles, Taxidea nnd Arctictis.

Thc nnticlinal vertebra is also R point of change in motion. Antc-

riorly, in the chest region, motion is relatively slight, and the zygapophyses are simple, flat or slightly concave and Fonvex, and placed in a nearly horizontal plane. There is an abrupt change at the posterior zygapophyses of the anticlinal vertebra to a more complex type of articulation. The function of these complex zygapophyses is to prevent any dislocation as a result of the greater and more varied movements in the lumbar region. The simplest type of posterior thoracic and lumbar zygapophysis (FIGURE 22A) is found in the Miacidae and Fissipedia; here the articulatory surface of the posterior zygapophysis is moderately convex, and faceslaterally and downwards; the anterior zygapophyses arc concave and face inwardn and upwards. The majority of the Creodonta, including the Hyaenodontidae,

$y&@ A B C

FiauRx 22. Posterfor vlew of lumbar vortebrao. showlng oxtent of artlculatory surfnca of poetedor zygspophyses in hravy h o . A. Type found b Mladdae and Flrwlpodln. J3 Typo found Ln Llmnocuon. C. Rovolute zygapophyffa of Pnfrfofdfs.

primitive Oxyaenidae, Mesonychidae’ and some Arctocyonidae, havc a more complex articulationof atonguq and groovc typr (FIGIJRE 22R). This differs from the miacid type in that the nrticulatory area of thv post,erior zygapophysis is extended onto this dorsal surfaw. Dis.qai:iis, an early meaonychid, and the primitivc hyaenodontids Sinopa, Thiiwqonf i n d probably Prolimnocyon, arc intermedintc! to the miacid type in that the dorsal extent of the articulatory surface is slight. Pafriofetis has a highly complex, concavo-convex lumbar articulation (FIGURE 22C), termed “revolute” by Osborn (1900, p. 274). An incipient stage in the development of revolute articulation is seen in the posterior thoracics and anterior’ lumbam of advanced Ozyaena, PaZueonicti.9, L imnoyon potens and later mesonychids. Thc obvious function of revolute zygapophyses is to prevent torsion, but the reason for its occurrence in Palriofelis and absence in other creodonts is not clear. The fact that a similar type of articulation is present in certain artiodactyls suggested to Cope (1889, p. 211) that. it was correlated with A trotting gait.

IIEN IsOhr: J'SEI ' T x ) C I I F N I ) I 210

Behind the anticlinal vertebra, the ceritra and neural arches are lengthened and broadened, and the small metapophysis of the anterior thoracics becomes divided into large, distinct an- and metapophyses. The transverse or costal processes do not appear until the first lumbar vertebra. They are relatively short and robust in the broad-skulled Pseudocreodi, especially so in Patriofetis; this is another indication of an ambulatory gait. Lininocyon potena is peculiar in that the spinal nerves leave the anterior thoracic vertebrae through n foramen in the pedicel, rather than through a notch. .

Flaunt 23. Dorsal view of sacrum. A. Thlnocyon ccfox. Amer. Mw. No. 18081. Lwlcn nntural dzn. B. PafriofeUs feroz. Amer. Mus. No. 1607, half natural dze.

SACRUM: (FIGURE 23.) The members of this group have threr sacral vertebrae, the usual number in fiesipedes, and probably the primitive number for creodonts. The anterior zygapophyses are of the lumbar type, whereas the posterior are much more simple. The lateral mss, to which the pelvis is fastened, arises largely from the first sacral vertebra, but in Palriofelis, Palaeoniclis, and Limnocyon polens i t is supported to some extent by the second, indicating perhaps a stronger pelvic attachment. In the Limnocyoninae there is an anterior procese from the lateral mass, entirely distinct from the anterior zygapophysis, which increases the area for attachment. In the presence of this process the Limnocyoninae resemble other Hy- aenodontidae and the Miacidae, and differ from the Oxyaenidae and

220 A N N A L S ATEW YORK ACADEhiY OF SCIENCES

Mesonychidae, in which it is entirely lacking. The transverse costal processes of the Limnocyoninae arc essentially like those of Tn'temno- don; the first forms the lateral mass, the second is barely indicated, and the third is wide and distinct. In Patriojelis and probably in Oxyaetul they are all united indistinguishably, and are not widely expanded laterally.

CAUDALS: All the crcodonts which are not especially adapted for running are charactcrizcd by a relatively longer and stronger tail than is present in most fissipedes. Powerful transverse processes are Crcscnt on the anterior caudals, but are reduced in size posteriorly, and become subdivided into anterior and posterior processes on the seventh or eighth caudal. A primitive feature is that the neural canal is enclosed for n considerable distance, up to the ninth caudal in Paln'o- jelis, to the tenth in Limnmyon, and to the twelfth in Trilemnodon. The number of caudal vertebrae, though not known exactly in many creodonts, is large. Twenty-six are preserved in Palriofelis (Amer. Mus. No. 1507), and therc may have been twenty-eight or more.

It is impossible to tell from the vertebrae alone whether the tail was prehensile. It probably was in some of the Miacidae which were almost certainly arboreal. In most of the Pseudocreodi, however, the long, powerful tail was merely an inheritance from arboreal :kneestors (Matthew, 1904) and had lost its power of prehension.

Ribs In the Pscudocreodi, therc are th i r teen ribs on each side in Oqjaena,

S i m p a nnd probably Palaeonidis, fourteen in Hyaenodon, Tritemno- don and Palriofelis, and probnbly fifteen in I imnoq jon polena. Of thcsr, th r last two to four lack the tuberculum. The first rib is short, wick and flat, but thc other ribs are rounder in section, or less f la t tend than is usually the case in fissipedes. Patriojelis has heavy ribs, widely bowed-out t o form n robust thorax such as occurs in the hesvicr and more ambulatory hsipcdes. O q a e n a has morc slender ribs and thorax, but the latter is not compressed as it is in cursorial carnivores. Thinocyon has relatively slender ribs.

Sternum T h r manubrium of T h i m c y o ~ (Amer. hlus. No. 11524) and Limno-

cyon (Amer. Mus. No. 13138) is similar to that of Tritentnodotr. Anterior to the facet for the first sterns1 rib it is broad, flat dorso- ventrally, and thin; posteriorly i t is slender and oval in section. In Patriojelis the manubrium is of a very different type; it is relsively long, deep and laterally compressed, and the ankrior part is not st

DENISON: PSEUDOCREODI 22 1

all expanded transversely. The mesosternal elements, six in number where known, are relatively short and robust in Patriojelis and Palaeonictis, and somewhat longer, morc slender, and slightly constricted in the middle in Thinocyon, Sinopa, and Trikmnodon. The xiphistcrnum was not preserved in any of the specimens cxnmincd, nnd was probnbly cartilaginous.

FioirnE 24. Uternl vjow of right smpuln. A. Thinocuon mediur. Amor. Mus. No. 12164 h. PutrlofcJclls feror. Amor. Mus. No. 1508. one thlnl onturnl dzo forrr thlrtlr nntuml du?.

Fore Limb SCAPULA: ( I ~ I C U I ~ E 24.) 'l'hc scapula is well known in the brontl-

skulled Psrudocreodi only in Palriojelis. l'hc frngmcntary rciiuiiis rcsemblc other creodonts in the following characters which may bc regarded 8fj primitive for thc Carnivorn: subequnl supra- and infrn- spinous fossnc; well developed, projccting ncromion; prominent metacromion; and distinct, projecting coracoid. Thc only creodont in which a clavicle has been determined is Tn'ternnodon, where it is much Icss reduced than in any recent carnivorc. The relatively long ncromion, to which this bone is attached, suggests a correspondingly largr clavicle in the Limnocyoninae; PalriojeZis has a rclntively shortcr and broader acromion, but i t is n safe inference that the clavicle was hettcr developed than in any fissipede.

Thc differences between the scapulae of the Limnocyoninae and Oxyarnidae are due largely to different adaptation. Thc Limnocy- oninat-, cspccially Thinocyon, ngrcc with Sinopa and other semi-

222 A N N A L S NED' YORK A C A D E M Y OF SCIENCES

cursorial types in having a relatively narrow scapular blade, shallow fossae, and weaker spine, acromion, and metacromion. The Oxyaeni- dac, especially Palriofelis, have a much broader blade, deep fossae, high spinc, and robust acromion and metacromion. This type of scapula is approximated most closely among the more ambulatory fissipedes, such as Nasua. Oxyaena, Palaeonictis, and Oxyaenodoir arc of nn intermediate type.

Froune 26. Antodor vlcw of rlght humerus. A. Thinocyon rnedfur. Amcr. Mw. No. 12154. four thlnla natural &e. B. Urvocna pfolypus . Amor. Mua. No. 16867. two thlrdn nntural dzo. C. Pnfriofelfsfcror. Amer. MUM. No. 1607. on0 thlrd natural slze.

HUMERUS: (FIGURE 25.) The primitive creodont humerus was moderately short and robust, with a prominent, massive greater tuberosity, strong lesser tuberosity, high deltoid and supinator crests, wide cntepicondyle with a large foramen, small ectepicondyle, shallowly grooved distal articulatory surface, and shallow olecranon fossa. Such a humerus is found generally in Paleocene Creodonta, and occurs in Ozyaena and Limnocyon. Comparison with recent carnivores indicates that it belongs to an essentially ambulatory type.

The Limnocyoninae and Oxyaenidae differ in the form of the deltoid

crest. In the former it tapcrs off gradually at about the middle of the shaft; in thc latter it extends nearly two thirds of the length of thc shaft and ends abruptly. I t is moderately high and robust in Limtzo- cyon and in small species of Ozyaena, more strongly developed in Palaeonictis and in larger Ozyaenu, and exceptionally high and wide in Paln'ofelis, indicating extremely powerful pectoral and deltoid

B

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E

F

Prbv~c 20. A. OZUU(M platypus. anterior v l o r of right radlus and ulna. Aoicr. Mus. No. IGES7, natural &o. B-D. Prc~llmal v loa of right radlas: B. Ozvocno platypus; C. Poltfolrifs feroz; D. Limnocyon ccrus. E-F. Dlstel vlow of right radius: E. Owoma plalypw; F. Limnocyon D C ~ U S

muscles. On thc othcr hand it is relatively low and weak in Ox!penu- don, inore so in Thinocyon and Thereufheriim; this is partly tluc* to sinallcr s i z , n d partly to a more cursorial typc of locomotion.

The shallow olecranon fossa and fairly deep anterior supratrochlcar fossa of Palriofelis show that the elbow-joint was quite angulate and could not be straightened entirely under ordinary circumstances. This considerable angulation is a clear indication of an ambulatory gait, and together with thc large size of this form, explains the extremely

4

221 A N N i i L S NEW YOllK ACADEMY OP SC‘IE”(.‘K*’i

robust crests and processes for the attachment of muscles, wliicli fuiictioii as much to support as to move the animal. The olecranoii fossa of the Limnocyoninae, espccially of Thinoojon, Machucroides, mid Ozyaenodon, is deeper than in the Oxyaenidac, signifying either a greater range of motion at the elbow or a less angulatr limb. I n any case, 3 more cursorial type of locomotion is certain. The differcut gait aiid sirialler size account for the more slender crests and processes for iiiusclc attachment.

The distal articulatory surface is relatively wi&! and shallow in the broad-skulled Pscudocreodi, as in primitive creodonts generally. In tho Oxyaenidae the trochlear surface for the ulna is of small antrro- posterior extent, and is very shallowly grooved, indicating 3 limitcd range of motion. The Limnocyoninac, especially Thinocyon and Ozyaenodon, approach more cursorial types in having a more deeply grooved trochlear surface, which is extended farther into the anterior supratrochlear and olecranon fossae; this allows a greater range of motion, but restricts it to a more antero-posterior direction.

ItADIUS: (FIGURE 26.) The radius of the broad-skulled Pscudo- crcodi is modcrately robust, with the shaft somewhat curved in thc typical carnivore manner. Thc head of the radius is round-oval in Ozyaenu plalypus and Thinocyon, indicating that these forms retaincd to a considerable degrec the power of pronation and supination that the ancestral arboreal placentals possessed (Matthew, 1904, p. 813). However, since it may bc only a heritage character, it is, by itself, no proof that the habits of these two forms were arboreal. The radius of the other Oxyaenidae has moderately to very wide-oval heads, which a1lows little twisting on the ulna. In Limnocyon, Ozyaenodm and some species of Oxyaena this is correlated with the assumption of a more cursorial gait.

The distal articulatory surface for thc scaphoid and lunar bones is quite wide antcro-posteriorly, and shallowly convex; it restricts movement little at this joint. There may be a small contact with the cuneiform, at least in some of the Pseudocreodi.

ULNA: ( F I ~ U R E 26A.) The ulna agrees with that of other primitive creodonts in having a robust shaft, flattened dorso-ventrally at the distal end, but unreduced and freely movable on thc radius. A more or less ambulatory gait is indicated by the long olecranon which furnishes a moderately strong lever-arm for M. triceps brachii, allowing powerful but relatively short motions of the forearm. This process is especially long and robust in Pdriofelis , and is shortest in T h i m c y o n and Oqaenodon, which are more cursorial. The upturning

DENISON: I’SEUWCREOUI 225.

of tlic olcvmmoii, which is found in creodonts geiwrally, iiic’aiis that less straightening of the elbow-joint is possible. In cursorial forms, which liavc Irss motion st the shoulder-joint and more at the elbow, the olccrsnon- tcnds to be downturned to allow a greater rangc of motion.

Faoune 27. R~smmtJom of &11t nianus of Lllo broad-ekullod Pwutlucrcodl

‘l‘h proxbnnl end of the olecranon lnclts a distinct goovc in most of the broad-sku!!ed Pseudocreodi ; in Thinocyon and Qzyaenodon, and to a greater extent in truly cursorial forms, there is a marked groove for the tendon of the caput longurn of M. triceps brachii, since there is greater motion of this tendon over the olccranoii in the latter forms.

226 A N N A L S NEW Y O I K ACADEMY OF SCIh”CE*S

Most creodonts have thr olecranon twisted inwardly, and the semi- lunar notch placed obliquely to the axis of the shaft. This obliquity is greater in the Limnocyoninac than in the Oxyaenidae. I t means that the forearm is not in the same vertical plane as the humerus, but that the distal end of the ulna is directed somewhat outward relative to the humerus. The articulatory surfacc for the trochlea of thv humerus is relatively wide, and only slightly convex laterally. Iir

truly cursorial forms motion a t the elbow-joint is limited to a inor(’ strictly antero-posterior direction by a greater convexity of this surface and a corresponding deeper grooving of the trochlea of th(b humerus. Thinocyon and Oxyaenodon approach the cursorial typr i n this, aa in other respects. The lesser sigmoid notch, or surfacc for thv head of the radius, is only slightly concave in most of the members of this group, in correlation with the wide-oval head of the radius and the reduced power of pronation and supination.

MANUS: (FIGURE 27.) The manus of the broad-skulled Pseudo- creodi is of a very primitive type as shown by the following characters: (1) The carpal elements are free, with rare exceptions: the scaphoitl and centrale are fused on one side in a specimen of Limnocyon rmm (Arncr. Mus. No. 12155); the scaphoid, centrale, and lunar are unit(*(] in Oxyaenodon dysclerus (Cam. hlus. No. 3051). Such fusions occur a individual variations in occasional Paleocene and Lower Eocene Creodonta, and are general in the later Miacidae and Fissipedia. (2) The carpus is of an alternating or interlocking type, with the lunar resting almost equally on the centrale, magnum and unciform. (3) The pollux is large and more or less divergent aa indicated by the convex and somewhat inwardly facing facet on the large trapezium; this character is found in many Paleocene and Eocene mammals, and according to Matthew (1904) is inherited from arboreal placental ancestors. (4) The ungual phalanges are cleft. Since this character is found in most of the Creodonta and several other carly groups of mammals, it is probable that i t is a primitive character which has been lost in such forms aa the Miacidae where the terminal phalanges nre much compressed laterally.

The manus of the Limnocyoninac differs from that of the Oxyaenidw and resembles tha t of thc Hyaenodontidac in several rather fundamental’ points. This resemblance is so close that two forms which are adaptively similar in the limbs, Linzmcyon among the Limno- cyoninae, and Trikmnodon among the Proviverrinse, are hardly distinguishable from the foot alone. The lunar-unciform contact is large in the Oxyaenidae, small in the Limnocyoninac. The ant&ior,

tion-articular face of the inngnuin is moderately largv in the Oxyucni- dac, w r y small in thc Lininocyoninnc. The unciform is dccp proximo- distally in t h v Oxyacnidac, whcrcns it is shallow and widc transvcrscly in the Lininocyoninac. Thc radial articulatory mrfacc of the scaphoid has a very charactcristic posterior expansion on the ulnar sidc in the Oxyacnidac, cntircly lacking in the Limnocyoninac. Thc trapezium is rclativcly larger and broader in the Oxyacnidac. The ungual phalanges arc flattcncd dorso-vcntrally in the Oxyacnidac, whcrcas thvy arc sornewhat lntcrnlly compresscd in thc Limnocyoninac. ’l’hc diff(wncc in proportions is morc adaptive; thc foot is rclativcly roIJust, short, and spreading in the Oxyacnidac, whilc it is longer and inore slcndcr in thc Limnocyoninac.

Matthcw (1909, p. 324) considered thc symmetry of thc foot to bc nn csscntial difference bctwccn thc Miacidac and Mcsonychidac which hc called paraxonic, and thc Pseudocrcodi which hc called “approxi- rnatcly mesaxonic.” Thc paraxonic symmetry of the Iatcr, highly cursorial hicsonychidac is obvious, but the differences between thc symmctry of the feet of the othcr families is less clcarly marked. If subcqual digits 111 nnd IV, and shorter digits I1 and V indicate a paraxonic foot, Oxyaena, Pafriojelis, and Palaeonictis are ncarly as parasoiiic :ts any of tho Miacidac. But the diflcrciice is so small frol l l the cwly Hyncnodontidac in which digit ‘111 is longest, :md I1 :Lid I V arc slightly shortvr and subequal, that it can hardly bc considered fundaincntal, especially since thc difference is less clcarly marked in the hind foot. The mesaxonic symmetry of the Hyaeno- dontidac is cvcn lcss certain, since metacarpal IV is appreciably longer than 111. In thc absence of any marked difference in the carpus, it appears that thc primitive symmetry of all the Creodonta, including the Ynlcoccnc Mcsonychidac, is fundamentally similar, and intermediate bctwccn parnxonic and mesaxonic.

The manus of thc broad-skulled Pseudocreodi is plantigrade to subdigitigradc, indicating an ambulatory to subcursorial manner of locomotion. Paln’ojelis is the extreme of the plantigrade type as shown by the following characters: (1) Foot robust, short and sprcad- ing. (2) Carpus short proximo-distally, with the elements articulating loosely to allow relatively frce and varied movements. (3) %dial articulatory surface of scaphoid extending so far anteriorly that it ncarly mects thc distal articulatory surface; this implies an angulation between the forearm and wrist which is not found in.cursoria1 types. (4) Pisiform short and robust. (5 ) Digits I and .V relatively long. ( G ) Mctacarpnls and proximal phalanges short. (7) Metacarpals

sprcnding and articulating loosely. (8) Distal articulatory surface of ~netacnrpals lacking any distinct fossa abovc i t ; this is an important character, indicating that the angulation between thc metacarpals and proximal phalanges is slight. In digitigradc forms the articulatory surfacr is more sharply convex and is continued into a distinct.fosss above it nnteriorly, so ns to mnkc possible n grentw angulntion at this joint.

Palaeoiiictis and Oxyaenu platypus nrr nlso cxtrcnicly plan tigr:itlv furins, while Limnocyon and the other spcvks of Oxyuenu arc slightly less so, judging from the above criteria. Thitwcyon and Onjuetiodon, relntively small, light-limbed forms, might bc classed as subdigitigrade. T h e foot is relatively longer and more slender; the pisiform is longer; digits I and V are slightly reduced; the metacarpals arid proximnl phalanges are longer, and the former articulate more com- pactly; the distal articulatory surface of thc metacnrpals is morc sharply convcx and hns a small fossa nbove it.

Hind Limb PELVIS: (FIGURE 28.) The pelvis of the Oxyacnidac is chnractcr-

izcd especially by the grcat dorsal expansion of the upper part of tlic ilium, and by the extrmwly strong lateral ridge which bounds it ventrally. Since this is the area of origin of the glutral musclcs, thv latter must have been exceptionally strong. Thc gluteal muscles abduct and rotate the femur, and their great development signifies varied motions of the latter bone, as opposed to the more strictly antero-posterior motion of cursorial types. This characteristic cx- pansion of the dorsal plate of the ilium is found also in the Hyaeno- dontidae nnd primitive Mesonyehidae, but to a lesser degree; it is not known in other Carnivora. The lateral ridge on the ilium is developcd less strongly in the Limnocyoninae than in the Oxyaenidae, and is only faintly marked in the small, light-limbed Thinocyon. The expansion of the ventral part of the lateral face of the ilium is nlso correlated with varied femur motions, since it is here that M. iliacus has its origin. The strong ilinc crest and the eversion of the anterior cnd of the ilium indicate powerful back muscles (M. longissimus dorsi), especially in the Oxyaenidae.

The cotyloid notch in the acetabulum, through which passes thc ligamenturn terea, is a good indicator of thc manner of locomotion. I n truly cursorial types it is deep and narrow; in ambulatory, and especially arboreal types, where femur movements are varied, it is relatively shallower nnd wider, allowing freer motion. In most of the

I ) EN IS0 N : I’SL U UOC NEODI 229

Imntl-skulled l’scudocrcodi it is rnodcratcly shallow aid open, agrcc- ing approxiniately with Z’rucyon among the ksipedcs; i t is slightly dcwpor and narrower in Oxyaerra platypus and Thinocyon, rcscmbliiiy Il’elis in this respect.

’l’hc ischium is slightly loiigcr in thc Liinnocyoninac than in the Oxyacnidac, and as a rcsult thc obturator forarncii is longcrsval ill

thv formw. In iionc is thc ischiuni as long as thc ilium, for it is cs-

Ipraunr. 28. Latcral view of rlsllt pelvis. A. Limnocuon potcns. Amer. hlus. No. 13138. two clilrds natunl slzo. B. PatrfoleIis fcroz. Amer. Mw. No. 1608. one tblrd n a l u ~ ~ l dze.

pccially in leaping and running forms that the ischium is clongatc. l’hc ischial spinc is strong, especially in the Oxyaenidae; its great dcvclopment is correlated probably with the large size of the tail. The pubic symphysis is of moderate length, but is not cspccially strong.

The femur of the broad-skulled Pseudo- creodi has the following characters in common with all primitive Creodonts: moderately robust proportions; greater trochanter high, massive; lesser trochanter strong and placed on the mesial side of the

FEMUR: (FIGUI~E 29.)

shaft ; third trochantw well developed; and trochaiitc~ic fossa dcop. 'I'hc proportions arc cqccially robust in the largcr forms, and thcrcforcl i n thc Oxyacnidac. Thc fcmur of Palaeoniclis is incomplctcly k n 0 ~ 1 1 ,

but is pobably coiisidcrably longer than rcstorcd by Sinclair and Jcpsvii (1!)20, FIGURE 1). Thc shaft of the femur in thc Pscudocrcodi and Mesonychidac has a peculiar curvature so that its axis passes through thc grcatcr trochanter, rathcr than bctwecn thc hcnd and thc

Pioonc 2U.' ' dtorlor vlcw of rlght fomur. A. LininocUvn poIcw, Amer. Mua. KO. 13138. two thlrda notun1 dze. B Pafrlofdfsfcroz. Amer. Bfus. No 1507. ono thlrd natural dzc.

grctater trochantcr CIS in othcr Carnivora. Thc strong dcvelopmcnt of thc trochnntcrs and the trochantcric fossa indicate that thc musclcs which twist, adduct, and abduct the femur arc correspondingly powcr- fully dcvcloped, and that this bone is capable of varicd movcmcnts. The head of thc fcmur in thc Oxyacnidae, especially in Patn'ojelis and Protopsalis, faces mesio-dorsally, showing that the shaft of the femur was dirccted somewhat laterally, and that the gait was rather strnd- dling; this suggests a robust body. In the Limnocyoninae the head fnces more mesially, and the limb was straighter, and more capsbte of cursorial locomotion.

D E N I S O N : I’SEliDOCNEOI)I 23 1

I t is a general rule, a t least among the Carnivora, that the patellar trochlea is relatively long, narrow, and deeply grooved, and the patclla is small in cursorial forms. In ambulatory types, the trochlca is shorter, -broader, and more shallowly grooved, and thc patclla is rclntivcly long, wide, and robust. The extensor of the tibia, hl. quadriceps femoris, which has its insertion on the patrlla, and whose

P A

Frbvn~ 30. Anterior vlow ofrlglit Cll)h and flhuln. A. Thinocyon oeloz. Amer. Mu. No. 13082. four thtrds natural 47.. n. Pofrfnfrlls frrnz. Amor. Mus. No. 1607, four ninths natural eke.

pull is extended to the tibia by the ligamentum patellar, is n more slender muscle with a faster action at poorer leverage in the cursorial types; it is a larger muscle with a stronger but slower action in ambulatory types. The range of motion of the tendon or patella over the trochlea is also much greater in cursorial forms. Judging by these criteria, most of the Oxyaenidae are ambulatory types, especially Patriofelis. The Limnocyoninae, except Limnocyon, have a relatively narrower and longer trochlea, and the patella is relatively small. The latter is partly due to the smallcr size of the members of this sub-

232 A N N A L S N E W YORK ACADEMY OF SCIENCES

family, but it is probable that they were sub-cursorial. The condyles and intercondyloid fossa are likewise somewhat deeper in the Limno- cyoninae.

TIBIA: (FIGURE 30.) An investigation of the tibia of the primitive creodont leads to the same conclusion as thc study of thc other limb bones, namely that the early carnivores were rather ambulatory. Oxyaena platypus and Limnocyon are near to the primitive type and agree in having a low, broad tubercle for the ligamenturn patellae, a moderately low and heavy cnemial crcst, a shallow fossn for M. tibialis anterior, flat, ungrooved astragalar trochlca, placed obliquely to the axis of the shaft, and a small astragnlar facet on the external side of the internal malleolus. The Inter species of Oxyaenu have a heavier tibia, and i t is exceptionnlly robust in Pntriofelis and Palaeo- niclis. On the other hand, Thinbcyon has a relatively long, slender. more cursorial type of tibia.

The very low tubercle for the ligamenturn patellae of Patriofelis and Palaeonictis is characteristic of ambulatory animals.; the levrragc is such that the pull of the M. quadriceps femoris, transmitted through the patellar ligament, results in a slow but powerful cxtenaion of thc shank. Thinocyon has a higher tubercle, approaching the condition of cursorial carnivores; the movement of the shank may be much morc! rapid with this arrangement. Thc cnemial crest is likewise rclativcly highcr and morc slender in Thinocyon, as in running types gcncrally; it is exceptionally low and massive in Palriofelis and Palaeoniclis. This crest tapers out gradually below the middle of the shaft in all the Oxyneiiidae; the Limnocyoninae resemble thc early Hyaenodonti- dae in that the cnemial crest ends more abruptly above the middle of the shaft, and usually has a peculiar emphasis near its distal end. The proximal fibular facet facee almost directly distally in the Oxyaenidae, while it facee much more laterally in the Limnocyoninae and other Hyaenodontidae. The fosaa for M. tibialis anterior on the lateral side of the proximal end of the shaft is generally rather shallow in the broad-skulled Pseudocreodi, indicating that this extensor of the foot is not as strongly developed as in running and jumping forms.

This is a primitive character, inherited from ambulatory ancestors which had relatively free movement at the ankle 'joint. The only creodonts which develop a deeply grooved astragalar trochlcn are the truly cursorial Mesonychidae and later Hyaenodontidae. The internal malleolus, which restricts lateral or twisting movementa at the tibio-aatragalar joint, has only a small mtragalar facet in the early

The astragalar trochlea is quite flat in all the members of this group. .


creodonts. It is somewhat larger and at a sharper angle to the horizontal nstragalar surface in the Limnocyoninac than in the Oxyaenidae.

I

I ~ I O U R E 31. Rastorjtlons of rJght pos of tbe broad-skulled Pseudocreodl

234 A N N A L S h’EIC’ YORK A C A D E M Y OF S C I E N C E S

FIBULA: (FIGURE 30.) Thc fibula is unrcduced in the membcrs of this group. In t,he Oxynenidae, cspecially Patriofelis, it is vcry robust, while a t thc othcr cxtrcmr it is moderatcly slender in Thinocyon. I t is frcely movable on the tibia; distally there is no distinct facet; the proximal tibia1 facet facrs dorsnlly in thc Oxynenidac and mcsio- dorsally in the Limnocyoninac. The distal end, or external mallcolus, retains n well developed facet for the cnlcnncuni in the Limnocyoninac. This is a primitivc character, found in most creodonts. I t is lost in most of the Oxynenidac, however; n modcratc fibulo-calcancar articulation occurs in Pulaeonictis, nonc in Oxyaena; thc vcry small one in Patriofelis is probably secondary. Thc fibulo-astragalar facet is oblique and may well transmit some of the weight to thc fibula.

Among thc chnracters of thc pcs which mny bc considcrod primitive, the following arc important: (1) Foot ns n wholr plnntigrade, pcntadnctyl, short, and spreading. (2) Tarsus rclativcly short proximo-distally, and brond. (3) Hallux somcwhnt divergent, as shown by the unreduced cntocuneiform with a sndd1c;shapcd distal articulatory face. (4) Astrngalus 1vit.h body untlccpcncd, trochlca short and only slightly groovcd, Inrge nstragalnr fornmcn, oblique fibulnr fncct, and wide, flat hcad. (5) Calcnncum with oblique cuboid facct, nnd well dcvcloped fibular fncet; thc latter is untlouhtcdly .z primitive chnrnctcr, but has bccn lost in Oxyacna, and thc smnll fibular fncet is probably sccondnry in Pub.iofeli.9. ( G ) A cuboid-t nstrngnlus contact. (7) The primitivc charnctcrs of t.hc inctnpotlials nntl phnlnngths are thc same as in thr mainis. -- 7 . h ~ Lipnocyoninnc t:losely rcacinblc t h(x Provivcwinnc nntl differ from the Oxyacnidac in sevcrnl characters. Thc foot ns n whole is shorter, more robust, and sprending in thc Oxynenidnc. Thc body of thc astrngnlus is flat and shallowly convcx in the Oxyncnidne, much dccpcr and more shnrply convex in thc Limnocyoninnc. Thc trochlear surface of the astragalus 4 limited to the body in thc Oxyacnidae, whereas it extends onto the neck in the Limnocyoninac; it is also lcss extensive proximo-mesially in thc Oxyacnidae. A wcll developed fibular facct is present on the calcancum of the Limnocyoninac, wherens it is small or absent in the Oxyaenidae. The astragalus-. cuboid contact is large in the Oxyaenidae, and much reduced in the Limnocyoninse. The groove for M. peroncus longus is dcep in the Limnocyoninae, and shallow irt the Oxyacnidac. The ungual phalanges differ in the same way as in the rnanus.

of the forc foot. Although metatarsals 111 and IV arc subequal in thc

PES: (FIGURE 31.)

Much the same may be said of the symmetry of the hind foot

DENISON: FSEUQOCREODI 235

members of this group, the symmetry is not truly paraxonic ns in the Mesonychidac, for the pressure of metatarsal 111 is transmitted to both the cuboid and navicular by the wedgc-shaped proximal end of the cctacuneiform. In Thinocyon thc cuboid face of the cctocunei- form is somcwhat more vertical, resulting in a more nearly paraxonic arrangement of the tarsus. In any case, the symmetry is not clcarly mrsaxonic as held by Matthew (1909, p. 324).

Thc earlier Oxyacnidae, Oxyaena and Palueoniciis, show every indication of a plantigrade pcs. The foot as a whole is-short, robust and spreading, with a broad, short tarsus and unreduced and somewhat divergent first digit. The tuber calcis is short and robust. The body of the astragalus is quitc flat and the trochlea is very shallowly grooved and of limited nntcro-posterior extent, while the surface for the internal malleolus is small and a t a slight .angle to the trochlear surface. The metatarsals arc short, spreading, and interlock little; their distal articulatory surface is not sharply convex, and there is little or no depression above it on the nnterior face. Paltiojelis shows an even more complete plantigradism, the foot being excessively short, robust, and spreading, and the tarsus is even more shortened and broadened.

The pes of the Limnocyoninac is longer, morc slender and less spreading. Thcrc are many indications that it is less plantigrade than that of the Oxyacnidac, but it is probably no more than subdigitigrade, even in the light-limbed Thinocyon. Thc entocuneiform is niorr rcducrd than in Osyrrenn, indicating a less divcrgcnt hallux. The tarsur; IX~ 3 whole is dccpcr proximo-distally and more compact than in thr Oxyncnidne. The body of the nstragalus is deeper, the trochlear surface longer, and the facet for the internal malleolus more sharply defined than in the Oxyacnidac; but the trochlea is not deeply grooved as in truly cursorial forms. The tuber calcis is relatively longer and more slender than in the Oxyaenidae. The metatarsals are lcss spreading, and there is a deeper fossa above their distal articulatory surfaces, especially in Thinocyon. These characters and many others suggest a subdigitigrade posture for Thinocyon, while Limno- cyon is intermediate to the more plantigrade Oxyaenu.

ADDTAI’ION Feeding Adaptation

Prolirnnocyon and Thinocyon: These two genera nre similar in their small size, long, slender jaws, tuberculo-sectorial lower molars, and rclativcly slender premolars and canine.;. Among thc Fissipedia

236 A N N A L S N E W YORK ACADEMY OF SCIENCES

they have their closest analogues in Viverriculu or Genetta, among the Mnrsupialia, in Dasyurus. These recent genera are all largely carnivorous, feeding on small birds and mammals, and it is probable that the diet of Prolimnocyon and Thinocljon was of n similar nature, although some of the .smaller species, such as T. mustelinus, mny have been insectivorous, or partly so.

Limnocyon is similar in structure to Thinocyon, but is larger and has n deeper jaw, and more robust teeth, skull, and jaw, especially in L. potens. There are no very close parallels among the Fksipedia; in the Marsupialia, Sarcophilus shows many resemblances, but has a much shorter skull and better developed shear. All that can be snid is that Limnoqon was probably largely carnivorous and cnpablc of crushing bones.

Oxyaenodon differs from Limnocyon in its better developed cnrnm- sial shcar, broader skull, and heavier jaw. In these respects it resembles Sarcophilus more closely than does Limnocyon. It wns n smnll, but probably powerful carnivorous form, such 4s Sarcophilus.

Thereuthen’um is n very small form, yet shows every evidcncc of nn cxtrcmc cnrnivorous adaptation in its slender premolars and highly specialized sectorial molars. The fnunn of thc Phosphorites of Qucrcy, in which this form occurs fairly abundantly, includes mnny small mnmmnls and birds on which Thereutherium might have fed.

Machaeroides is an extrepely cnrnivorous derivative of the enrlicr Limnocyoninae showing o, close analogy with some of the smaller species of Felis in its lower jnw and teeth. The shearing blnde of thc rnrnnssinls is not as well devcloped as in Felis, but is vrry advanced for n Midtllc Eocenc enrnivorc. Thc premolars nrc slcnrler nncl shmriiig, mtlicr than crushing, and arc reduced in thc antcrior part of the jaw. Since the aabre-tooth specializations a re only incipient in this genus, its feeding habita were doubtless very similar to thosc of Felis.

Apataelurus is n very close parallel to thc true sabre-tooth cnts, cspecinlly Hopbphoneus and Eusmilus, differing mostly in the development of RiIv as the main carnassial. Its manner of feeding was similar, without o, doubt, to that of the Machaerodontinae. According to Matthew (1910, p. 305) these highly specialized carnivores were ndapted for preying on the thick-skinned, slow-moving “pachydcrms,” which they killed by stabbing, ripping or gashing with their long upper canine tusks. A large element of the fauna of Uinta B, in which Apatuelurus was found, consists of just such forms, cspecially nrnong the titanotheres.


Oxyaena was primitively not unlike Limnocyon verus in the adapta- . tion of the skull, jaws, and teeth. The lower molars were essentially tuberculo-sectorial and the upper were tritubercular; however, sincc none of the Upper Paleocene creodonts had truly sectorial carnassials, this does not mean that they wcre not truly carnivorous. The latcr species of Oxyaena were larger, with a better developed carnassial shear, fairly robust, crushing premolars, strong canines, and heavy

.jaws. They wcre well adapted for eating meat and crushing hones. Palriojelis includes heavy-jawed forms with powerful skulls, well

dcvcloped shenring molars, and robust, quickly blunted premolars and canines. Among the fissipedes, the ncarcst analogue is Hyaena and it is cntirely possible that Patriojelis fed on carrion to some cxtcnt, but thcre is no cvidcnce for this hypothesis. Wortman (1804, p. 161) bclicved that P. jerox habitually fed on turtles for the following rcnsons: (1) hc thought Palriojelis was aquatic; (2) turtles wcre abundant in the Bridgcr beds; (3) coprolites with fragments of turtlc honcs have been found in thc Bridger beds; (4) the powerful jaws and teeth werc capablc of crushing turtle shclls. Although, as will bc shown hclow, therc is good reason for bclieving that Pdriojelis was not aquatic, therc is much to be said for Wortman’s theory, sincc turtles might have becn captured in swamps, river bordcrs, or shallow water. Morcovcr, therc is no other carnivorous form known in thc Bridger beds which is as well adapted in its feet and tccth for catching and cating turtles. Matthew (1909, p. 432) concluded that P. jerox “wns probably an indiscriminate and voracious feedcr like thc modern hyacnas, gluttons, ctc.” Sincc t h k form WJIS a slow, 1uml)cring anirnnl, unable to capture spectly prey, this is n rcasonnblc conclusion; it i R n safe assumption that turtlra and alligators formcd part of its tlict.. P. coloradensis and P. uUa are smaller, but probably had n similar diet: P. comptessa, however, was a much less robust animal, not only in its jaws and teeth, but also in its limbs. It was better adapted for catching arid eating some of the contemporary slow-moving hcrhi- vores.

Sarkastodon carries the tendencics of Patriojelis jerox to an extrcmc. Thc teeth in the posterior part of thc jaw arc of n very spccinlizcd meat-shearing type, whil? thc anterior teeth are trcmcndously robust and rapidly bluntcd. The skull and jaws arc capable of powerful crushing action. The conclusions as to the feeding habits are much thc same as for P. jerox. Turtles may have formcd part of thc diet of this animal also, sincc thcy occurred plcntifully in the Irdin Manha beds.

238 A N N A L S NED’ YORK ACrlDE, l lY OF SCIENCES

Palaeonictis and Ambloctonus have no close analogues among recent carnivores. The short, heavy skull and jaws, and the robust prcmolars resemble thosc of the larger species of Omjaena, but the shearing function of the molars is poorly dcvcloped. This, together with thc ambulatory gait, may mean that they were rather indiscriminntc feeders, such as Hyaena, and it is probable that carrion formed a large part of their diet,

Locomotor Adaptation ARBOREAL: An arboreal type, modified for running on branches,

is difficult to distinguish from a terrestrial, ambulatory typr by its skeleton alone. Such an animal is charnctcrized especinlly by: (1) divcrgcnt, somcwhat opposablc pollux and hnllux; (2) frec power of pronation and supination of the manus; (3) pcrhaps a prchcnsilc tail; (4) sharp, curvcd claws; (.5) the frcr and varied movcmcnts of thv limbs; and, (6) the prcsrncc of n rlnviclc.

(1) Thc pollux and hallux arc divcrgcnt to some dcgrcc in all the Oxyacnidae. Since this is a heritage character, carried over from ancestors which were ccrtninly arborcal (Mntthcw, 1904), it is no proof of nrborcal habits. The divrrgcnw is somrwhnt Icss in thc Limnocyani nae.

(2) Thinocyon and Oxyaena platypus arc‘ the only broad-skulled Psrudocrcodi with a round-oval head on the radius. A11 the others hayr a modrratcly to w r y widc-oval head, indicating rcduwd ability to pronntr and supinatc thr hand.

(3) Tlir tail of tlw Eocoric I’srotlocwodi tvns lorig aiid strong, but thcrc arch no certain c~ritwia by which it m n be told whethcr it \vns prchcnsilr or not. It, niay I)c only an iiihcritnnw from arborcal nnccstors.

(4) The ungunl phalanges of all the Oxyaenidac arc short, bluntcd and flattened dorso-ventrally; they are entirely unadapted for holding onto bark. The claws of thc Lirnnocyoninae are longer and shnrper, but arc little curyed, and are not fitted for climbing.

(5) The depth and width of the cotyloid notch of the pelvis is a single character which givcs a reliablc indication of the freedom of motion of the hind limb. In most of the Oxynenidae and in Litnnocyon it is moderately wide and shallow, but it is more of the type of a terrestrial ambulatory animal such as Procyon, rather than being extremely wide and open ns in thc arboreal Arctictis. In Thinocyon and Oxyaena platypus it is decper and narrower, indicating more restricted femur moverncnts.

( 6 ) The cluviclc was probably present and well developed in all of tlic carly Pscudocrcodi. This is another character which was inherited from arboreal ancestors, and has little udaptivc significancc, t t least in the Ewcnc.

In summary it inay be said that there is no good cvidcncc for :rrboreal habits in any of the broad-skullcd I’scudocrcodi. In the Oxyacnidac, the short foot, flat, blunt claws, slight ability to pronate and supinatc the manus, as well as thc reduction of the motility of the back, arc 311 against such an adaptation. Morcovrr, thc Upper Palcocciic and Lower Eoccnr forms occur in bcds which include rnostly a11 open country fauna, and have LI vcbry small urborcal clcment. Among thc Limnocyoninac, Thinocyon is the only form which has the power of pronation and supination well dcvcloped. But its fcet are subdigitigradc, and the divergence of the hallux is slight; it is most improbable that it is arboreal.

CUILSORIAL: None of thc broad-skullcd Pscudocreodi can bc classified as truly cursorial. Carnivora which arc fitted for such a manner of locomotion have a digitigrnde foot, long, compact carpus, tarsus and mctapodials, long forearm and shank, shortened tail, light limbs and body, and exhibit many other highly characteristic ndaptn- tions. Only Thi?iocyon illid Osyaenot lo~ , and pcd iup I’rolimnocyon and Thereulhcriuiu approach the cursorial type. T h r first two h a w ;L relatively long, cornpact foot which is subciigitigradc; the divcrgciicc of the pollux and hallux is rcduced; the forearm and shank arc moderately long; the body and limbs arc rclativcly slcndcr. They might be called subcuraorial.

AMBULATORY: This classification includes most of the broad- skulled Pseudocreodi, certainly Otyaena, Palriofelis, Palaeonictis, and probably Liinnocyon. All of them have short, spreading, plantigrade fect, short and heavy limb bones, and robust bodies. Numerous other characters indicating this manncr of locomotion havc been mentioned in the preceding section. The skeleton of Prolimnocyon is poorly known, but the pclvis, tibia and calcancum indicate a moderately light-limbed, ambulatory or subcursorial animal, probably similar to , ! i h p U . The excccdingly broad, spreading fwt of Patriofelis fcro t may bc an adaptation for walking on soft ground, perhaps in svamps and on river banks; this accords with the theory that they fed on turtles. The Bridger and Washakie formations, in which it occurs, are made up largely of deposits of streams, swamps, and flood-plains, and adds further support to this hypothesis.

FOSSORIAL: Thc only m c n i b ( ~ of the Pseudocrcotli which shows any indication of digging habits is an undcscribed Mongolian form.

24 0 A N N A L S NEW YOIlK ACADEMY OF SCIENCES

AQUATIC: The early stages of aquatic adaptation are difficult to dctermine from skelctal Characters alone. The most obvious skulctal distinction of 1~ truly aquatic carnivore is the shortening of the proximal and len@,hcning of the distal segments of the limbs. Wortman (1804, p. 161; 1902, p. 127) argued that Pdriofelis was ayuatic, but Matthew (1909, p. 429431) showed that the short tibia, mctapodials and phalanges are specialized in just the opposite way from aquatic carnivores. The same is true to a greater or less dcgrec of all the Oxyacnidae. Among the Limnocyoninae, Thinocyon shows a lengthening of the tibia, metapodials and phalanges, but thc proportions of the limb-segments resemble those of Felis as closely ns those of the semi-nquatic Mus&Ea. The sharply convex distal nrticulatory facet of the metapodials, with a distinct fossa above it, indicntes a flexible joint between the metapodials and proximal phalanges, with considerable anp la t ion at this joint. This is highly suggestive of a subdigitigradc, subcursorial manner of locomotion. In aquatic forms the flexibility of the joints of the feet is greatly reduced. The forefoot of .Ozyaenodon is relatively long also, but the lengthening of the forearm and the character of the distal articulatory surface of the metacarpals indicntes a subcursorial gait. In summary, there is no evidence that any of the brond-skulled Pscudocreodi were aquatic or cvcn semi-aquatic.

GENERAL RELATIONSHIPS‘ Relationships of the Limnocyoninae

In 1902 (p. 117) Wortman grouped Limnocyon, Thinocyon, Oxyamw- don, and Thereutherium in the Limnocyoninae, which he used as 3

subfamily of the Oxyaenidae, as opposed to the Oxyaeninae. Later authors have followed Wortman in retaining this group within the Oxyaenidae, but many have noted its close resemblance to the Hyaeno- dontidae, especially to the more primitive Proviverrinae. Matthew in 1905 (p. 72) states that “the relationship of Sinopa to thc Oxyaeni- dae, especially to Limnocyon, is not yet clear. There is a great deal of rcsemblance in skeletal characters, a marked diversity in the more significant features of the skull. Most of the msemblance, perhaps all, is to be explained as due to retention of primitive creodont characters, but some may indicate a nearer relationship of Hyaenodonts to Oxyaenids than to any other creodont family. . .” I n 1909 (p. 330) and 1915 (p. 71) he is convinced that the Oxyaenidae (including the Limnocyoninae) and Hyaenodontidae are nearly relate& and unites them in the superfamily Pseudocreodi. Scott in 1913 (p. 573)

bclicvcs that tlrc Lininocyoninnc “wcrc survivors of still more ancient :uid primitive progenitors of the family [O~yacnidac]’~, and that, “Liirinocyon . . . tends to indicate a common origin for thc oxyaenids and hyacnodonts . . .

I t is the conviction of thc author that the similarity bctwccn the slichton of the Limnocyoninae and that of the Provivcrrinac is indic- :itivc of n very closc relationship. On the other hand, thc rcsemblancc of thc Limnocyoninac and Oxyacnidac is a result of the retention of priinitivc crcodont characters and of thc somewhat similar adaptation in both, and is thus duc to parallelism. The most important character which the Oxyacninae and Limnocyoninac have in common is thc nbscwx of M i , and thc developmcnt of hl+ as the main carnassials. This has been considercd by Matthew 3nd others to be a fundamental difference from thc typical hyaenodontid condition, in which IM$ are thc largest carnassials. But Sinopa mordax and Prolimnocyon, which have M$ more or less reduced, arc ideal intcrmedirrtc forms and show how the typical proviverrine could give rise t o the oxyaenid arrange- mcnt. The proportions of the skull and jaws of the Limnocyoninae arc intermediate; the most specializcd members of the group closely npproach, but ncver quite attain the proportions found in the earliest oxyacninc. The post-cranial skeleton of the Limnocyoninac is much closer to that of thc Proviverrinae than to that of the Oxyacninae; Limiocyon is similar to Tritemnodon, while Thinocyon, and perhaps Prolininocyon and Omjmnodon, approach Sinopa in proportions.

Below is presented a list of some important characters in which the Limnocyoninae rcsemble the Proviverrinae and differ from the

11

Oxyacninae :

Litnnocyonincu: and Provivrmmc p ) two-roocod, emopt In some spednlized

19.‘ simplo. usually two-rooted. tacking

P’ nnd MI with modarately short meta-

Ylicaring Iilndo of ~rnass la le laps perfectly

Cheok tooth-row rclativoly long. Lowcr jaw very long and shallow to

modoratcly short and deep. Yytnphyals relatlvoly long to fairly short

and doep. Angle of jaw slender. projoctlng. upcurved

and pointed at ttp. Foca Felatlvely long. Skull narrow to moderately wide. Preglenoid m t none.

gonero.

dlstlnct protocope.

stylo.

. dovelopod.

OzyM.;rinue Pf singl+rooral or absent.

P douoloplng protocono curly: t h r w rooted. except in oarlioat form.

Pj and MI with long motastylo.

Shearing blodo of carauglals myidly

Cheok tooth-row modelately to vcry short. Lowor jaw rolatlvely deopor and slrorkr.

Symphyds very short and deop.

Anglo of jaw deop. robust. projoctlng

Face considerably shortened. Skull wide to very wida. Preglonold most preaent.

periected

little, bluntly rounded or truncate.

Liiiirwcyoninae unil I'rouivem'nru: I'zrocclpltal proccw tliln. apatulatu. and

I k 4 a l ncrvc cxltlng tlmugli foramm d1rcct.d mostly poaterlorlp.

atyluimstolduum prlmitlvurn.

Xacruni wltli tllstlnct anterlor prouw froin lateral mans.

Xlanubrlurn cxpandlng anteriorly nnd llottcned dorao-vcntrally .

I>cltolcl c m t of humerus tapering oll grwlually a t rnlildlo of sluft.

I)ors~l hordcr of llluin rnoddcratcly cx- pantlcd.

I'roxlml tll)bl facet of fll)ula facing In- tcmally and proxlmally.

(huniial crcst of t l l h ondiny almvu inldtllu of shaft with a pccuUar ompbads dlatally.

l k x rclaUvcly longcr. icsv robust. antl sprcacUng.

Itodlnl mrfacu of solpliold unoxpnnclcd ponwriorly on ulnar sldo.

UncUorm widc. but hall^^ proxliiio- Illrttnlly.

Lunar-unclform cantact small. Dody of o s t r a ~ l u s ~nodemtcly dcwp. Trochlrar surfaco of nvtngalua oxtcntln

onto neck and is morc cxtendvo proximo- mcslally.

('ulainqum wirli Inwo flliulur facet.

( : ~ l ~ ~ l t l ; r ~ t i a g ~ l ~ ~ contact w i i u l l . Ungual plmlangcs I:rtonlly cuiiiI)rc.wd.

Oz ymincle

I'arwclpl(al process mow mI)ust anel cll- rcct4d morc vcntrally.

Yrrclal nerve uxltlnfi rnoro vcntnlly through fornmcn stylomastoidcum clu- llnltlvum (Oxyocno antl Pafriofclis) .

Sacrum wlth no indlcatlon of latcnl ProcClia.

Manubrlum lowrally c o i n p r d . not cxpandlng much anwriorly.

Dullold C P C S ~ of humcrun endlnK nl)ruptly OIWUL two thl& of way down rlmfc.

Doml lmrdcr of fllum w r y Illgh.

Prodinn1 tll)lal famt of muin fuclng nclrrly

Cncmlal e m t of t l l h tamring OR giudu-

I."t sliorter. rohuat. and spwdlng .

Rndlal surfam of ficapliold wlth n clurac- terfstlc pstcrlor Rwclllng on lnteral ddr.

UncUorm nnrrowcr. nnd dmpcr proxlmo- dlstally

Lunar-undform contact large. Body of estngalua f i t . T w h l m r rmrfaw of n s t m g a l ~ ~ llnilted (u

body nnd shortcr -nt proxlrno-mcslnl cornur.

Cirlorncum with Illmlar fitcot ~ m ; ~ l l or uaunlly a lwnt .

(:ullold-antrawIun contact largo. Ungual plialangcw tlorso-vcntrally l l i r k

tlircctly proxlmally.

olly below mlddlo of shaft.

tcnnl.

Although IIICW ci~uincratiori of characters lends to no cwtaiii conclusion, a study of important features of the skeleton indicntes that thc resemblance to the Provivcrrinne is more fundnmentnl, that to the Oxyaeninae more superficial nnd adaptive. The Limnocyoninnc nrc referred therefore to the Hyacnodontidae, while the Oxyneninnc are rctnined in the Oxyacnidae. It is believed that this expresses the true

' relationship of the subfamily morc correctly, and it emphasizes the fact that thc similarity to the Oxyacnidac is due largely to parallelism.

Origin of the Limnocyoninae I t has bccii shown above that the Limnocyoninac arc wry closely

nllicd to thc Provivcrrinae, and the intcrmcdintc forms Prolininocyon and Sinopa inordax leave little doubt that the former were derivcd from the. latter. When Prolininocyon first appears in the lower pnrt qf the Lower Eocene, it is not far removed structurally from Sinopa, and it is a safe conclusion that the divergence of the Limnocyoninnc from the Proviverrinae began na late as the Upper Paleocene. -The central type of both subfamilies wns probably such a form as Siiwpa.

The inox r<?motv :iiiwstry of the Hyac!iiodontidac is uiict:rtain. ‘l’htr family is unknown iii the Yalroceiie with the possible exception of the hloiigoliaii 0pidhops:aZix and Sarcodon. The following Rroups of creodonts occur in thc! lower anti middle Paleocene:

( 1 ) Miaeidw, alwudy showing the typical earnassid spccializiitioir of P A :uid MT, arid thus oxcluded from ancestry to other families of crrodon tn.

(2) Mtwiiychidac*, exhibiting the characteristically long orbital region, low glenoid with a pregleiioid crest, very long jaw with robust symphyyis, single-rooted first premolars, reduced Ma, and reduced parsconid. These and other characters show that the Paleocene mesonychids arc widely separated from the hyacnodontid line a t this varly date.

(3) Arctocyonidac, as used by Matthew (1937), including a hetero- gcnous assembltlgc of primitive creodonts, representing several divergent phyla. The Arctocyoninae are shown to be entirely distinct by their low-crowned, qusdritubercular molars. The Triisodontinac pivallel the Mesonychidae in sknll, jaws and teeth, and arc as far rcmoved as the latter from the Hyaenodontidae. The Oxyclaeninac and Chriacinac include somewhat more generalized forms, which resemble thc Hyacnodontidae in many respects. But all the know11 genera are specialized in certain ways which exclude them from direct ancestry. For example, the first premolar is single-rooted or absent; there is often a rudimentary hypocone on the upper molars; the trigonids of the lower molars are low; the paraconids are reduced; Ms is reduced in the Oxyclmninae.

In conclusion i t may be said that the genus or subfamily which was anceitral to the Hyaenodontidae is unknown, but waa not far removed from the Chriacinae or Oxyclaeninae.

Relationships of the Palaeonictinae Pahonict is waa described by de Blainville as a member of the

Viverridae (1842, p. 79). Cope in 1875 (B, p. 446, 447) included Ambloctonus and Palaeonictis in his newly created suborder of Creo- clonta, and in 1877 (p. 89) referred them both to a separate family, thc Ambloctonidae. Osborn and Wortman in 1892 included thesc genera in the Palaeonictidac (synonym of Ambloctonidae), which they considered ancestral to the Felidae through “Aelurotherium.” In 1909 (p. 410, 411) Matthew showed that the derivation of the Felidae from the Palaeonictidae or “ Aelurotherium” was impossible, and placed Palaeonictis and Ambloctonus provisionally in the Oxyaeninae. In

244 A N N A L S NEW YORK ACADEMY OF SCIENCES

1915 (p. 42), he states that these genera form a separate group, i.e., subfamily, within the Oxyaenidae, but gives it no name. Sinclair and Jepsen described a nearly complete skeleton of Palaeonictis in 1920, and concluded (p. 171) that “the skeleton of Palaeonictis is typically oxyaenid, and there can be no question of the propriety of placing this genus in the Oxyaenidae rather than in a family of its own.”--

The conclusions arrived at after the present study arc entirely in accord with those of Matthew, and of Sinclair and Jepsen, but the two genera are placed in a separate subfamily, the Palaeonictinae, because of the different specialization of the molars. The Upper Paleocene Dipsalodon serves to bridge the gap between the Oxyaeninae and Palaeonictinae in tooth-structure. MT and M u are subequal and much like those of Oxyaenu platypus, 0. aequidens and Dipsalidictides. It is only the details of the tooth-construction which indicate that Dipsalodon belongs to the Palaeonictinae rather than the Oxyaeninae. So far as known, Palaeonictis agrees with the Oxyaeninae in the characters of the skull, jaw, and post-cranial skeleton listed above, and differs correspondingly from the Limnocyoninae.

Origin of the Oxyaenidae In the upper Paleocene, when the Lirnnocyoninae had not yet be-

come distinct from the Proviverrinae, the Oxyaenidae already possessed the typical family specializations, and were beginning to diverge along the two subfamily lines. Before that time, no oxyaenid is known. Among the early Paleocene Creodonta, the Triisodontinae resemble and approach the Oxyaenidae in many respects; some of the similarities are listed below. The jaw is relatively deep and robust, especially in Triisodon. The chin is steep and the Symphysi8 is large and deep, with a vague indication in Tn’isodon of a division into two lobes posteriorly, as in the Oxyaenidae. The angle of the jaw is much aa in the Palaeonictinae. The skull haa a relatively wide glenoid with a preglenoid crest, similar to that of Palaeonictis. The zygomatic arch is strong, and deepens somewhat posteriorly. The nasals of Eoconodon are constricted at the middle, widest at the maxillo-frontal suture, and taper posteriorly. The post-orbital processes and supraorbital ridges resemble those of the Oxyaenidae. The lower incisors are small and crowded, and in Eoconodon I s is larger than IL-2 aa in the Oxyaenidae. The canines are fairly robust and similar in form to those of Palaeonictis and Oxyaem. The first premolars are one-rooted. In Eoconodon Pz is erect and P3-x lean posteriorly, exactly aa in Dipsalodon. The lower premolars are moderately robust. P+ hbs a

DEN ISON: PSE UDOCREO DI 24 5

well developed anterior basal cusp, as in the earliest Palaeonictinac. There are often internal cuspules on the heels of Pa and PT, as in Dipsalodon and Palaeotiicfis. MT-T are subequal and M3 is greatly reduced in Goniacodon, less so in Triisodon. The trigonids of thc lower molars are rather high in Triisodon. The talonids of Goniacodoit resemble those of Oxyaena in having simple, indistinct cusps; in Tri - isodon and Eoconodon the talonid cusps are large and distinct as in the Palaeonictinae. The Triisodontinae approach the Oxyaenidae in the small size of M3, and in Goniacodon and Triisodon in the reduction of MZ, especially at the postero-external corner. The post- cranial skeleton resembles that of the early Oxyaenidae very closely. Especially characteristic is the deltoid ridgc of the humerus, which is robust and terminates abruptly below the middle of the shaft. The cnemial crest of the tibia is broad and low and tapers off gradually towards the middle of the shaft, as in the Oxyaenidae. The astragalus and calcaneum are very similar in the two groups, and the latter has the fibular facet reduced.

Not all of these similarities are found in any one of the three genera of the Triisodontinae, and several important differences from the Oxyaenidae occur. For example, the paraconid of the lower molars is greatly reduced, except in Eoconodon, whereas it is enlarged in the Oxyaenidac. The protoconid and metaconid are usually more connate than in the early Oxyaenidae. The presence of M$ and the relatively unreduced M I are characters which would be expected in the ancestors of the Oxyaenidae. The metastyle of the upper molars is very small; in this respect, the difference is less from the Palaeonict- inae. The pnracone and metacone are more distinctly separated than in the Oxyaenidae. PS is three-rooted with a small but distinct protocone; P3 of Triisodon is not very different from that of Palaeonictis, but in the earliest Oxyaeninae it is a simple, two-rooted tooth, without a protocone. Since the protocone is present almost invariably in the Paleocene Creodonta, it is possible that it was lost, and that a new cusp appeared in the Oxyaeninae.

On the whole, it appears that direct derivation of the Oxyaenidae from any known member of the Triisodontinae is impossible. But there are so many points of resemblance between the two groups that it is probable that they had a common and not very remote ancestor. This raises the question of the propriety of the use of the superfamily Pseudocreodi to unite the Oxyaenidae and Hyaenodontidae. Although the parallelism of the Limnocyoninae and Oxyaenidae might be taken to indicate a close relationship, the early Proviverrinae show no

24 6 ANh‘ l l tS h’ElY YURK AC‘ADEAfY OF SCIENCES

:ipproach to the Triisodontinac. thew’s (1909) superfamily groupings should bc rcviscd.

I t is possiblc tliat ccrtaiii of Mat-

Possibility of Descendants of the Oxyaenidae Certaiii authors have becii misled by the supcdkial rcscniblaiicc!~ of

thc: teeth of Pahiofelis to those of the Yclidac into bclieviitg in 3 relationship Lic*t\vcwi thc! two groups. J,eidy, in dchscribing Pattiofelis i c l l a , refcrrrd it to the “cut family” (1870, 1). 10). Marsh bc!lictvcd /~iiii.nofelis (synoiiyin of Palriojelis) to be allicd to the cuts (1877, 1). 369). Cope believqi that the Oxyaenidat: gave rise to tho Fvlidac. (1880 A, p. 81; 1884 A, p. 264). However, Scott pointed out in 1889 (p. 242) that the analogies bctwecii the tceth of cats and oxynciiids were only superficial sincc they are - between teeth which arc riot homologous. Wortman (in Osborn and Wortman, 1892, p. 101) was uiiconvinced by Scott’s masoning and concluded that the “Palaconic- tidac,” including Palaeonictis, Ambloctonus and Palriojelis, wcre probably ancestral to the Felidae. Adams (1896, p. ’442) rcfcrrcd I’alriofclis “k idyonus of Wortman to Aelurotkeriicvi, which he con- sicl(wt1 iiitcrmctdiatc betwccn Palaeonictis and thc cats. In 1000 (p. 410 nnd 419) Matthew thoroughly discussed the problciii ant1 cwiic.ludrd that Aelurotkeriuni was thc milk dentition of Palrinfelis :tiid hciicc had h V and MT as the main carnassials, instead of P*/MT as in the Fclidae; and, that Palaeonictis was truly oxyncnid nnd iii

no way.related to the cats or other fissipedes. In 1894 (p. 157) Wortman first proposed the theory that Patriofezis

was ancestral to the seals; he defended this idea in 1899 (p. 146) and in 1902 (p. 128). Scott (1895, p. 720) was sceptical from the first, believing that thc gap between the Oxyaenidac and Pinnipedia was too great to arrive at any such conclusion. In 1900 (p. 270) Osborii concluded that the trend of adaptation of thc Oxyaenidac was divcr- gent from that of thc seals, and that the two were unrelated. Matthew (IYO!), p. 41341G) carefully analyzed thc evidence and concluded that thcro wm littlc i i i favor of Wortinan’s hypothcsis. On the eon- trary, lie concludcd that thc Pinnipedia “arc derivable from the

. 11

I t :ipp~irs, thcrcforc, that the Oxynenidrc dicd out at the ciid of Arc*toitl lcissipcdin, with cspccial nffinitit!s to the Ursidtrc.

tlic ICoccirc without leaving nny successors.

.

24 7

Fronar 32. PhyloReny of the broad-rkulled Prwudocreodl.

248 A N N A L S NEW YORK ACADEMY OF SCIEWCES

PHYLOGENY The conclusions concerning the relationship and phylogeny of the

broad-skulled Pseudocreodi are presented diagramatically in FIGURE 32. In the Oxyaeninae, Dipsalidictides is represented as a primitive side line. There are apparently two phyla within the genus Oxyaena: (1) large, robust, broad-toothed forms, starting with 0. aequidens and culminating in 0. forcipata and Protopsalis; (2) relatively small, slender, narrow-toothed animals, beginning with 0. platypus and ending in 0. lupina and 0. ultima; 0. gulo is connected with 0. transiens ... by intermediate forms, but approaches the aequidens-forcipatu line in robustness. Protopsalis tigrinus is intermediate to Palriofelis, but is not considered to be ancestral to any of the species of the latter genus because of its large size. There is a considerable gap between the known species of Palriofelis and Oxyaena. P . compressa is probably derived from the 0. platypus-0. lupina phylum because' of its slender premolars. P. ulta and P. ferox'are possibly offshoots of the 0. aequidens-0. forcipatu line. The derivation of P. coloradensis is uncertain; in its small size, very robust premolars, and relatively small Mu i t is quite distinct from the other species of the genus. The Mongolian Sarkaslodon is derived from the larger and more robust species of Patriofelid.

In the Palaeonictinae, Dipsalodon is an ideal ancestral type for PaZaeonictis, but the known species is probably not the actual ancestor. There is nothing to debar Palaeoniclis from being the progenitor of A rnbloctonus.

Prolimnocyon is shown as the central type of the Limnocyoninae, connecting them with the Proviverrinae. From it arose three separate phyla : (1) the cat-like Machaeroidinae; (2) the small, slender-jawed Thimcyon; (3) the larger, more robust, deeper-jawed Limnocyon; this latter genus may have given rise to Oxyaenodon. The European Theractherium is probably the result of a long, separate evolution which took place during the period when North America and Europe were not connected. The ancestral type may have been a primitive limnocyonine, such as Prolimnocyon, which could have lived in Europe in the Lower Eocene; or Thereutha'um may have been derived directly from an enrly proviverrine, some of which are known in the Lower Eocene of Europc..


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1896. ~

The extinct Felidac of North Amerin. Amer. Journ. Sci. IV. 1:419-444.

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IDescribes nnd figures Palaconiclis gigunka (76-79, pi. I S ) , which he

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[General discussion of the Creodonta nnd description of Oztjaena forci-

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1876. Mnmmiferes foossiles nouvcaux provciinnt dcs dCp6te dc phosplintc dc

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iotc relntivc h In prhencc du gcnrc Orymin parmi Ics MammifOlrs

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chaux du Quercy. Compt. licnd. Acad. Sci. Pnris 82: 288,289.

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lf96). J

fowiles du Qucrcy. Bull. Soc. Philomnth. Pnris VTI. 6: 120, 121. 1882.

1884. Descriptions dc quelquea Mnmmif&rw fossiles des ,Pliospliorites tlu Qucrcy. Ann. Soc. Sci. Php. Sat . Toulouse 1884: 1-46. 711. 1-1.7.

I“Oqnnm” g d i m descrihcd nnd figurcd (23-25. 711. 7).)

Gervais. Francois Louis Paul. 1859. Zoologic e t pnlhitologic fmripinrs. Dcuxi&mc Cdition. i-viii + 1-514.

[l’trlntonirfis gigniilrcr dewrib4 nnd figured (225-226. fg. 26; pl. 26, Jigs.

f i n . f-6f + 711. f-84.

11, 12).1 Granger, Walter.

1938. A ginnt oxynwid from tlic Uppcr Eocenc of Mongolia. Arner. Mus. Novitates 969: 1-5. jg~. I-6.

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Hay, Oliver Perry. 1902. Bibliogrnphy and catalogue of the fosail Vertehrata of North Americn.

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Jepxn, Glen Lowell.

1930A. Stratigraphy nnd peleontology of the Paleocene of northenstcrn Park Proc. Amer. Phil. 80c. 69: 463-528. j igs . 1-4 +

[Originol description of Dipsoldon niolflrrrti (524-525. 711. IO, j g s . 8,9).1

County, Wyoming. Ill . 1-10.

DEN I SON : PS E U DOC RE0 D I 25 1

1930B. New vertebrate fossils from the Lower Eocene of the Bighorn Bnsin,

IOrjginal description of Dip8,solidictiar amplus (128. PI. 4; jgs. I , 2).] Wyoming. Proc. Amer. Phil. Soc. 69: 117-131. pl. 1-4.

Klaauw. Cornelis Jkcob van der. 1931. On the auditory bulls in some foossil mnmmnls, with ngcncrnl introduction

to this region of thc skull. Bull. Amcr. Mus. Nnt. Hist. 62: 1-352. jigs. 1-18.

/Numerous rcfercnces to this rcgion in Creodonts.]

Lechc, Wilhelm. 1015. Zur Frngc nach dcr stammesgeschichtlichen Bcdeutung des Milchgebis-

2001. Jnhrb. Abt. Syst. 38: 275-370.

IDescription of thc milk dentition of T l ~ n c t d h n i t r n ~ (347-348. j i 4 . y .

sc8 bei den Siiugeticrcn. 11. j igs. 1-126‘.

I!?O-t!?l) and I’utriofdi.9 (350).]

Leid y , Joseph . 1809. The cxtinct mammnlinn fnunn of Dakota and h’chrnskn. dourn. .\end.

[First URC of tlic family name Hynenodontidac (a).] Nnt. Sci. Philn. 11. 7: 1-472. pl . 1-90.

1870. Remarks on E1mmosarrru.s ptofyuurus and othcr fossil vcrtchrntcs. Prof. Acnd. Nnt. Sci. Philn. 1870: 9-1 1 .

[I’drzhjcltk d!u, new genus and species (10-1 l).) Contrihutions to tho cxtinct vertebrntc fnunn of tlic Wrdcrn Tcrriforics.

[/’dn‘oJrl;x t r / / r t drsrrilml nntl fimirccl ( 1 14, 115. 7 d . 2, f i . IO).]

1873. Ikcp. IT. S. Geol. Surv. Tcrr. 1: 14-358. ? ) I . I-.?;.

. Lydekker, Richard. 1884. N o t e on sonic fossil Cnrnivorn find Rodcnlin. C h l . Mng. IJ. Der.

111. I : 442-445. J ~ . Y . I, t. I”OxyoPnn” g n l l i w descrilml nnd figurctl (445. JQ. 2).]

1886. Cnteloguc of thc fossil Mnmmnlin in tlir Dritish Muwum. Part I. i-xxx + I-268.3~~. I-.%?.

I“0tyaena” gallior described and figured (35-37. A. S).] 1904. The ancestry of the Carnivora.

[Felidae derived from Palaeonictidae through Aelurothmium; mnraupinln Knowledge 1: 61-64. jigs. 1-6.

derived from Mesozoic “Creodontq”.]

Marsh, Othniel Charles.

1872A. Preliminary description of ncw Tertiary mnmmnls. I’nrt I. Amrr. Journ. Sci. 1x1. 4: 122-128.

lLimnocyon verus, new genua and species (126, 127).] 1872B. Preliminary description of ncw Tertiary mnmmnls. Part 11. Anicr.

[Descriptions of the following new forms: Litnnojclis jmor, IJitnnr,jclG

1872C. Note on n new genus of carnivores from the Tertiiiry of Wyominp..

Journ. Sci. 111. 4: 202-210.

latidenu, Iimnucyon ripariuv, Thinocyon vrlox. I

Amer. Journ. Sci. 111. 4: 406. [Refers hinnofrlia la!zi?mv to new genus, Orrocyon.]


1877.

1893.

Introduction nnd fiucccssion of vertebrate life in America. Amer. Journ.

[Considers “Limnojelis” as allied apparently to the cnta.] Note on n Bridger J3ocene cnrnivore. h e r . Journ. hi. IV. 7: 397. [Rcfere Limnocyon v m to Sinopa, and L. riparius to the new genus,

Sci. 111. 14: 337-378.

Telmalonjm.]

Martin, Rudolf.

1906. Revision der obereocaenen und unteroligocnenen Creodonten Europas.

[Describes ThereuIherium (587-596. p l . 16, jigs. 11, 13) ; refem “ o m j m ” Rev. S u i ~ ~ e 2001. 14: 4054300. pl . 16-19.

gall& to Parozynena, new genus.]

Matthew, William Diller. 1899.

1901.

1904.

1905.

1906.

1909.

1910.

1915.

1937.

A provisional classification of the fresh-wnter Tertiary of the West.

[Oryoenodon dysodus, new genus and species (491.1 Additional observntiona on the Creodontn. Bull. Amer. Mus. Nnt.

[Classification nnd relationships of the Creodonta.] The arboreal ancestry of the Mammalia. Amcr. Nnt. 38: 81 1-818. [An important theory concerning the nnccatral mnmmal.] Notes on the osteology of Sinopa, a primitive member of the Hyaeno-

[Resemblance of Sinopn to the Oxyaenidae indicates nenr relationship

The osteology of Sinopa, a creodont mammal of the middle Eocene.

[A complete description of Sinopa, and comparison with other creodonts.] The Cnrnivorn nnd Insectivorn of the Bridger Basin, middle Eocene.

[An important paper for its descriptions, classification, nnd discusaion of

The phylogeny of the Felidae. Bull. Amer. Mus. Nat. Hist. 28: 289-

(Aelurofherium not ancestral to the Felidae; describes the adaptation of the Machaerodontinae.]

A revision of the Lower Eocene Wasatch and Wind River faunas. Part I. Order F e w (Carnivora). Suborder Creodonta. Bull. Amer. Mus. Net. Hiat. 34: 4-103. fqs. 1-87.

Bull. Amer. Mus. Nat. Hiat. 12: 19-75.

Hi&. 14: 1-38,jig.~. 1-17.

dontidae. Proc. h e r . Phil. Soc. 44: 69-72.

(721.1

Proc. U. S. Nnt. Mus. 30: 203-233. j iqs. 1-20 + pl. 16.

Mem. Amer. MUR. Nnt. Hist. 9: 28S567.jgs. 1-118 + pl. 4h-6%

the relationships of creodonts.]

316. figs. 1-16.

[A ayatematic reviaion, with a description of several new forms,] Paleocene faunas of the Sen Juan Basin, New Mexico. Trana. Amer.

[The earliest known creodonta described and illustrated.] Phil. h c . 11. 30: 1-510. h a . 1-86 + pi. 1 - 6 4

Matthew, William Diller; h Granger, Walter. 1924. New Carnivora from the Tertiary of Mongolin. Amer. Mus. Novitates

[Original description of Didymocbnus cnlgafei and D. berketji.] 104: 1-9. .&JS 1-7.


1925. New creodonts and rodents from the Ardyn Oho formntion of Mongolia. h e r . Mus. Novitates 193: 1-7. fig3 1-9.

[Original description of Ardynicfis fuuruncu1~in.J

Note sur le terrain nouvellcment dbcouvert h Meudon. Bull. SOC. Chi,

[Descrihes a tooth of “Lotifre“; this is Palaconiclis, and is the first

Orbigny, Alcide Charles Victor Dessalines d’. 1836.

France 7: 280-291. 1 f q .

oxynenid mentioned in the liternture.] Osborn, Henry Fairfield.

1892. Pdaeoniclia in the Americnn lower Eocene. Nature 46: 30.

1895. Fossil mnmmals of the Uintn Basin. Expedition of 1894. Bull. . h e r . Mua. Nnt. Hiat. 7: 71-105. fqs . 1-17.

[Describes n jaw of “? Ilymodun” (78. fq. S ) , lntcr made the type of Oxyuencdon dysodua.]

The Huerfnno Lake basin, southern Colorndo, nnd i t s Wind River and Bridger faunn. Bull. Amer. Mus. Nnt. Hist. 9: 247-258.

[Describes Oxyaena hirerfanen.& and Pdriofelis “ulta” = Palriofelirc colorudensis. 1

1900. Ozgacnnn nnd Pafriafelis rcstudied as terrestrial creodonts. Bull. Amer. MU. Nnt. Hist. 13: 269-279. f q s . 1-8 + pi. 18, 19.

[Maintnina thnt these genera wcre terrestrinl or pnrtly nrborenl, nnd thnt their feet were digitigrnde or subdigitigrade; skcletnl restorations of Otyoena nnd Palriofeltk (pl. 18, IB).]

Cenozoic mammal horizons of wstern North Amcricn; with fnunnl lists of the Tertiary Mnmmnlin of the West, by W. D. Mntthew. Bull. 0. s. Geol. Surv. 361: 1-138.frgs. 1-16 + pl. 1-9.

[Zones and horizons of Tertiary mnmmnh established.] The nge of mnmmnls in Europe, Asia, nnd North Amcricn.

[ h t o r a t i o n s of Oztjacna (fi. 4 4 ) and Pafriofelis (fq. 6,5).]

(Original deacription of Palaemidis occidenfdis.]

1897.

1909.

1910. i-xvii + 1-635. figs. 1-220.

1912. Craniometry of thc Equidnc. Mem. Amer. Muu. Nnt. Hist. 11. 1: 55-100. fis. 1-17.

[Gives the system of skull measurements used in this paper.]

Fossil mammala of the Waheatch and Wind River beds. Collection of

[Pnlneonictidne are believed to be nnceetral to the Felidae; the skull nnd

Osborn, Henry Fairfield; & Wortman, Jacob Lawson. 1892.

1891. Bull. h e r . Mus. Nnt. Hist. 4: 80-147. fqs. 1-18 + pl. 4.

jswa of Palaeonicfia ocCidetl(a1ia are described (104-106. pl. 4.1 Peterson. Olof August.

1919. Report upon the mnterial discovered in the Upper Eocene of the Uintn

[Describes Ozyaenodon dysclerus (42-45. pl. 34, jigs. 1-2) and Limnocym Basin. Ann. Cnrn. Mus. 12: 40-168. f q s . 1-19 + pl. 34-47.

doughm’ = L. polens (45-48. pl . 34 +jigs. tl-ld).]

Plant& Raimond Louis Gaston. 1870. Sur Ies lignites infdricun de I’nrgile plastique du bnssin pnrisien.

[PalneonicliR giganlea from Meudon, Frnncc (210).]

Bull. Soc. G b l . France 11. 27: 204-216.figs. I, S + pl. I .

254 A N N A L S NEW YORK A C A D E M Y OF SCIEPCES

Schlosser. Max. 1887. Die Affen, Lemuren, Chiroptcren, Insectivoren, Mnrsupalier, Crcodon-

ten und Cnrnivoren des Europiiischen Tcrtiiik. I. Theil. Reitr. . Pal. &kr.-Ungnrns 6 (1-2): 1-224. pl . 1-9.

Y’/mctd/m-iwn dcscribed and figured (201-204, pl. 4, a).] ICenernl rclntionship, clnssification nnd phylogcny of the Crcodonfn;

Scott, William Berryman. 1888.

1889.

1 s93.

1.995.

1913.

1937.

M s.

011 some new nnd little k n m m crcodonts. Journ. Acnd. N3t. Sci.

[Describes skeleton of Prolopsolis fign‘nw.1 N o h on the ostrologv nnd systcmntic position of Dinidis jetinn Ikidy.

[Annlogics het\vccn Onyncnidne nnd Fclidnc superficial (2421.1 I\ revision of tlic North hmericnn Creodontn. Proc. Acnd. Nnt. Sci.

[Gcnernl rclntiondhip and clnssificntion of the Crcodont3.j On tlic Creodontn.

[Doubts that Pinnipcdin wcrc dcrived from Oxynenidae (720).] h liistory of lnnd mnmmnls in tlic western bemisplicre. New York 1913. (Itcstorntion of I’driqfclis (fi. 282) nnd Oxyacna (fi. 9841.1 A rernnrknhlc slrbrrtooth-like creodont from tlic Fdccnc of Utnh. Scicncc

11. 85: 454465. A Ixohlamntictil cntlikc mnndihlc from tlie Uintn Eocenc, Apnlaclttrit.~

knyi gcn. ct sp. nov. (Will hc pul)lislted sliorlly in t.lw Annnls of t l i v Cnrnegic Mu.seum.)

Phila. 11. 9: 155-185. pl. 5-7.

Proc. Acnd. Sat. *%i. Pliiln. 1889: 211-244. jigs. 1-7.

Philn. 1892: 291-323.

Rep. Brit. Assoc. hdv. $%i. 65th mceting 1896: 719, 720.

.

Sinclair. William John; & Jepsen. Glen Lowell. ;\ niountd ckrleton of l’nlnronicfiu. I’roc. Amcr. l’liil. SOC. 68: 10.1-173.

lnrzcription of the only nrnrly complclr Rkelctnn of n mcmher of this

1929. jp. 1-5.

suhfnmily.]

Teilhard de Chardin. Pierre. 1927. Les h!ainmif&res de l’&c&nc inffrieur dc la Dclgiquc. MEm. Mue. Roy.

[On pl. 6 are Q u m d several teeth whfch may belong to Pseudocreodi.]

Notea on thc Bridgcr (hccnc) Cnrnivorn. Amcr. dourn. Sci. V. 5 :

[Descriptive nnd systcmnt ic notes.]

Jordfundne og nulcvende Rovdyr (Cnrnivorn) fra Lngon Snntn, Minns

[.4n originnl clnssificntion nnd pliylogcny of Cnmivorn, hnsrd lnrgcly OII

Hist. Net. Bdg. 36: 1-33. &a. 149 + pt. 1-6.

Thorpe, Malcolm Rutherford. l9U.

2739.

Winge, Adolf Herluf. 1895.

Gerncs, Brmilien.

tooth-st~cturc.]

E Muxo 1,undii 2(4): 1-130. pt. 1-8.

1924. PnttcdyrSIaegtcr. IT. Rodcntin, Cnrnivorn, Primntes. 1-321. IClnsqificntion much as nhovc; Wingc’s system of cusp nornenclnture

npplied to creodonts.\

DENISON: XISEUIJOC/~EQDI 255

Wood, Horace Elmer 2nd; Scton, Henry; & Hares. Charlcs Joseph. l!lzjtj. Ncir dutu oii tlic J~hccric o l the Wiiid Itivcr U:L.iin, Wyoiiiiitfi.

[l’ufriojclis from tlic Wind Itivcr k s i i i , hliddlc I~hocc~rc.]

J’rui:. l’alcunt. Soc. 1935: 994, 3!)5.

Wortman, Jacob Lawson. IS!JI. Ostculo~y of /’uh-iojdk, LL Middle hocciic crcodoiit. I h l l . Aiiicr. Mus

I’l’liorougli dwcription of tlic skclcturi of I’cdrirf4is; I,clicvcs it is aquatic

Ilcstorutioit of Ozym,w I t ~ p i ~ i t c Copc, with clcscriptioiis of ccrtiiiii iiow Bull. ,liner. Mus. N3t. IIist. 1 2 : 13!t-

~ l l i c skclctoii dcscribcd und figured is probably 0.jorn’pdu; ulso dcscril)cs tlic skull nnd tccth of Orycu7rodon “ d y s d u s “ = 0. ( / y s c f c ~ w . ]

I!)OI-1‘30’2. Studics of lhccnc Mnrnmnlin it1 tlrc MnmIi collection, 1’cnl)ody Museum. Prrrt I. Cnrnivorn. Amcr. Journ. Sci. IV. 11: WJ-348,

Nut. Hist. 6: 129-lli4.jiq.s. f -5 + 711. I .

mid mccutrd to tlic + z ~ I . ]

spcicu of h c c n c crcodotits. 148. j j s . 1-3 + 1’1. 7.

18!)!t.

437-450; 12: 143-154, 193-206, 281-29G, 377-382, 421-432. 1901. 13: 39-46, 116-128, 197-206, 433-448; 14: 17-23. 1902.

[Dcucription, classification, revision, nnd relntionships of the Middle h c c n c cnrnivores; nn important paper.]

256 ANNALS NEW YOIlK AC'ADEdlY OF SCIENCES

Adaptntion, 235 .lclurotheriuni, 173 Ambloctonus, 176

hyaenoidcs, 176 mnjor, 176 priscus, 175 sinosw, 176

Apataelurus, 181 kayi, 182

Ardynicti, 182 Bibliography, 247 Brain, 215, f. 21 (214) Canineu, 188 Didymoconus, 182 Dipselidictidcs, 167

nmplus, 167 Dipselidictia, 167

nmplus, 167 Dipsalodon, 174

mntthewi, 174 -Distribution, 183,j. 3, /r (134, 1S5)

Femur, 229, f. f9 (230) Fibuln, 232, /. SO (231) Humerus, 222, j. 86 Hynenodontidne, 177 Incisors, 187 Jaw, ZOO,/. 11-15 (196-204) Limnocyon, 178

douglaasi, 179 potens, 179 ripnrius, 179 verus, 178

Limnocyoninue, 177 Limnofelia ferox, 173 Machneroides, 181

Machairoidinnc, 181 Manus, 226,j. 27 (225) Molars, 195, j. 6-16 (190-204) Oreocyon Intidens, 173 Oxynena, 167

eothen, 181

nequidene, 163 forcipnta, 169 gulo, 168 intermedin, 168 lupina, 169 pnrdalis, 169 platypus, 167 transiens, 16s ultimn, 169

INDEX Oxpaenidnc, I 6 6 Oxyucninae, 166 Oxynenodon, 180

dysclcrus, 180 dybodus, 180

. Pahconictinnc, 174 Pulaeonictis, 175

giganten, 175 occidcntolis, 175

Palute, f. 8-I 0 (1 92-1 94) Paroxyaenn, 176

gnlliac, 177 Patriofelis, 171

coloradensis, 171 compress, 173,f. 2 (172) ferox, 173 dtn, 173

Pclvis, 228, /. 28 (220) ha, 234, j. 31 (233) Phylogcny, 248, I. 32 i247) Premolars, 189 Prolimnocyon, 178

nntiquua, 178 ntnvus, 178 robustus, 178

Protopsalis, 171 tigrinus, 171

ILdius, 224, /. 26 (223) Illntionahips, 240 Ribs, 220 Sacrum, 219, /. 23 Sarknatodon, 174

Sccrpuln, 221, f. 24

Sternum, 220 Systematic revision, 166 Tail, 220

Thereutlieriuni, 180 thylncodes, 181

Thinocyon, 179 cledensis, 180.

Thinocyon medius, 179 mustelinus, 179 velox, 179

Tibia, 232, /. SO (23 I ) Ulnn, 224, f. 26 (223) Vertobrac, 216,f. 22 (218)

mongoliensis, 174

Skull, 207, j. 14-20 (203-212)

Teeth, 187,f. 6-10 (186-194)

the broad-skulled pseudocreodi

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