a clupeomorph fish from the gault (lower cretaceous)

Zoo1.J. Linn. Sac., 49, pp. 161-182. With 1 plate and 6figures

August 1970

A clupeomorph fish from the Gault (Lower Cretaceous)

COLIN PATTERSON, F.L.S.

British Museum (Natural History), London S. W.7 Accepted for publication 28 October 1969

__

A primitive clupeomorph fish, Sprufficefisguultinus gen. et sp. nov., is described on the basis of incomplete braincases from the Gault (Albian) of Folkestone, Kent. This is the earliest clupeomorph in which any details of cranial structure are known. Sprutficeps is more primitive than living clupeomorphs in having no recessus lateralis, auditory fenestra, pterotic bulla or sinus temporalis, and in having a heavily ornamented, entire skull roof, with the sensory canals bone enclosed and the post-temporal fossa roofed. The fish is too primitive to be placed in either suborder of Clupeomorpha, and is left incertae sedis. The primary characters of the Clupeomorpha are discussed.

CONTENTS

Introduction . Systematic description . Relationships . Clupeomorph characters . Summary References . Abbreviations used in figures .

PAGE 161 162 175 179 180 181 182

INTRODUCTION

I n the collections of the British Museum (Natural History) there are three small teleostean braincases from the Gault clay (Albian) of Folkestone, Kent, which have remained unidentified and undescribed since their acquisition in the 19th century. A fourth similar braincase, also unidentified and undescribed, has been found in the collection of the Institute of Geological Sciences, London. After preparation with an ‘Airbrasive’ machine, these braincases show certain features, especially the presence of very large prootic bullae, indicating that they came from a clupeomorph” fish. These are the first Lower Cretaceous clupeomorphs in which any details of cranial anatomy are known, and are therefore of some importance. I have compared the braincases with all species of teleosts described from the Gault, most of which are represented by more or less complete skeletons, and I feel confident that they do not belong to any known genus or species. Nor can I find any reason to align them with any other Cretaceous clupeomorph : the better-known genera, Diplomystus and Scombro- clupea, can be ruled out because of obvious structural differences, but there are many

* The name ‘clupeomorph’ (superorder Clupeomorpha in Greenwood, Rosen, Weitzman & Myers, 1966; cohort Clupeomorpha in Nelson, 1969) is here used in preference to the homotaxic ‘clupeifoim’ (order Clupeiformes) since the latter has been used by Berg and many later authors not in any phylogenetic sense, but purely as a basal, paraphyletic group in which all primitive teleosteans are included.

12 161

162 C. PATTERSON

poorly known Cretaceous fossils which have been placed in the Clupeidae (sensu lato) often on the most tenuous evidence, and there is no means of deciding whether the Gault braincases are conspecific with any of these. The braincases are described below as a new genus and species, primarily because of the information they yield on primitive cranial conditions in clupeomorphs, but also in the hope that those with access to supposed Cretaceous clupeids may be able to supply the rest of the skeleton of the fish. Because only the braincase is known, it is not yet possible to assign the new genus to any family or higher category within the Clupeomorpha.

1 am again indebted to Dr P. H. Greenwood for many valuable discussions.

SYSTEMATIC DESCRIPTION

Division Teleostei (sensu Nelson, 1969 :534) Cohort Clupeomorpha

Order Clupeiformes (sensu Greenwood et al., 1966) suborder and family incertae sedis

Spratticeps gen. nov.

Diagnosis. Cretaceous clupeomorph fishes known only by the posterior part of the braincase ; swimbladder diverticulum entering exoccipital and forming a very large prootic bulla, no pterotic diverticulum or bulla; no recessus lateralis, no auditory fenestra; pre-epiotic fossa minute ; skull roof heavily ornamented and entire, without supratemporal fossa or posterior frontal fontanelles, post-temporal fossa roofed, temporal foramen present but not exposed; sensory canals bone enclosed, supratemporal commissure passing through the parietals and supraoccipital, middle pit-line deeply incised on parietal and supraoccipital, no sinus temporalis ; basisphenoid and orbitosphenoid present ; occipital condyle formed by basioccipital only.

Type and only species: Spratticeps gaultinus sp. nov. Spratticeps gaultinus gen. et sp. nov.

(Plate 1, Figs 1 to 6)

Diagnosis. As genus, only species; neurocranium reaching about 14 mm in maximum

Holotype. BM(NH) No. 36311, an incomplete braincase (Plate 1). Material. The holotype and three other less complete braincases, BM(NH) Nos.

P.51016-7 and Institute of Geological Sciences No. GSM 112223. Horizon and locality. The BM(NH) specimens are labelled only ‘Gault, Folkestone’,

but GSM 112223 is from Bed V of the Gault (Price’s notation), at the base of the zone of Euhoplites lautus, Middle Albian in age. Dr H. G. Owen has examined the BM(NH) specimens and is confident that they are from the same bed.

breadth, probably about 30 mm in length.

Description All four of the neurocrania are very incomplete. All lack the parasphenoid and all

are broken across through the orbitosphenoid, lacking the anterior part of the orbit and the preorbital region. The most complete specimen, the holotype (Plate l), shows

A CLUPEOMORPH FISH FROM THE GAULT 163

most of the postorbital part of the neurocranium but has been abraded in the regions of the postorbital process, the dermopterotic, the epiotic/exoccipital suture on the hind face of the skull, the occipital condyle and the ventral edges of the prootic and basioccipital. The preserved parts of this specimen are 11 mm long, 9 mm broad. GSM 112223 is the largest specimen and must have been about 14 mm broad: the complete braincase of this individual would probably have been about 3 cm long.

The skull roof (Fig. 1) is smoothly rounded in the transverse plane, and apart from a median depression between the frontals is smooth and entire, with no posterior frontal fontanelles (Whitehead, 1963), no dorsal opening of the pre-epiotic fossa and no exposed post-temporal fossa or temporal foramen. Except for the depressed area between the frontals, which is smooth, the exposed upper surfaces of the frontals, parietals and supraoccipital are heavily ornamented with sinuous, branching ridges, radiating from the ossification centre of each bone. The supraoccipital (Soc, Figs 1, 2 and 3) separates the parietals as is usual in clupeomorphs. It forms a large part of the posterior surface of the braincase and on the skull roof its extent is greater than it appears to be since it is considerably overlapped by the frontals and parietals. There is a small, knob-like supraoccipital crest at the apex of the posterior surface of the bone. Near the back of the ornamented upper surface of the supraoccipital there is a well- marked transverse groove, interrupted at the mid-line but continued laterally on the parietal (mpl, Figs 1 and 2). This groove, which is interpreted as having carried the middle pit-line, is discussed below, together with the sensory canals on the frontal. Immediately behind the groove lies the tube for the supratemporal commissure, bone-enclosed throughout its length, which enters the parietal near the postero- lateral margin of its upper surface (stc, Figs 1 , 2 and 3) and passes through the parietals and supraoccipital, with a series of eight pores (stp, Figs 1, 2 and 3) opening posteriorly. It is not possible to say whether the commissure was continuous from side to side through the supraoccipital, but it certainly extended to the base of the supraoccipital crest, and if a wall of bone separates the two halves it can only be very thin. In living clupeoids and in Denticeps the supratemporal commissure is normally bone-enclosed in the lateral part of the parietal, but lies superficial to the medial part of the parietal and to the supraoccipital (Wohlfahrt, 1937, fig.2; Bamford, 1941 : 436; Greenwood, 1968, figs 3 & 6).

The parietal (Pa, Figs 1, 2 and 3) has a transversely elongate, ornamented anterior part, overlapped by the frontal anteriorly, and a lower postero-lateral part meeting the epiotic in a digitate suture. On the lateral surface of the skull the parietal meets the pterotic. Below the foramen through which the supratemporal canal entered the parietal, there is a vertical crest on the lateral surface of the bone, continued ventrally by the pterotic (Fig. 2). This crest separates two depressions, the post-temporal fossa (ptf , Fig. 2) anteriorly and the pre-epiotic fossa (pej, Figs 2 and 3) behind. The pre-epiotic fossa is a shallow depression floored by the epiotic, parietal and pterotic, with a small foramen at the junction of the three bones. The pre-epiotic fossa in most living clupeoids (Ridewood, 1905 ; Tracy, 1920; Wohlfahrt, 1937; Phillips, 1942; Chapman, 1948 ; illustrations in Svetovidov, 1952) is much larger than in Spratticeps, with a large foramen leading into a medially directed channel which in some genera opens on the skull roof behind the parietal: conditions are similar in the Upper Creta-


ceous Diplomystus brevissimus (Patterson, 1967, fig. 7). In Denticeps there is no pre-epiotic fossa ; Greenwood (1968 : 232) suggests that this is a secondary condition due to inflation of the pterotic bulla.

FIGURE 2. S’rcrtticepsgaultinus gen. et sp. nov. Reconstruction of the braincase in left lateral view, c. x 8. The course of the sensory canals and the outline of the temporal foramen are indicated on the key figure. For explanation of lettering see p. 182.

The post-temporal fossa (pi$ Fig. 2) is a shallow depression leading into a deep but narrow pocket extending antero-medially below the frontal, its medial wall formed by the parietal, its floor by the pterotic, sphenotic and frontal. At the apex of the fossa, within the frontal, there is a large oval fenestra, bounded by the parietal and frontal,

166 C. PATTERSON

opening into the cranial cavity. This fenestra (cf, Figs 1 and 2) corresponds to the temporal foramen of living clupeoids, but is not exposed as it is in living forms because of the more complete roof over the post-temporal fossa. In Diplomystus no temporal

StP

fim 0

FIGURE 3. Sprutticepsgaultinus gem et sp. nov. Reconstruction of the braincase in posterior view, c. x 8. For explanation of lettering see p. 182.

foramen is exposed on the surface of the skull, but here the roof of the post-temporal fossa is developed to almost the same extent as in Spratticeps. In Denticeps the temporal foramen is exposed, as in living clupeoids, but there is no distinguishable post- temporal fossa: probably it has been obliterated by inflation of the braincase, like the pre-epiotic fossa.


The frontals (Fr, Figs 1, 2, 4 and 5), of which only the posterior parts are known, meet medially in a sinuous suture in the floor of a median depression. This depression tapers and becomes shallow posteriorly, ending at the supraoccipital. A similar depression is present in clupeoids and many other teleosts. Posteriorly the frontal overlaps the parietal and supraoccipital, postero-laterally it meets the sphenotic and pterotic, enclosing the anterior part of the post-temporal fossa. The postero-lateral margin of the ornamented part of the frontal overhangs an antero-dorsally directed depression, the dilatator fossa (df, Figs 2 and 5), which is floored by the frontal dorsally, by the sphenotic and pterotic ventrally. The frontal forms the roof of the orbit, meeting the orbitosphenoid and pterosphenoid below.

At the lateral margin of the opening of the post-temporal fossa there is a large pore in the frontal (mi, Figs 2 and 5), the postero-lateral opening of the supraorbital sensory canal. From this pore the canal passed forwards within the bone into a wide tunnel above the orbit (ssc, Fig. 5 ) , from which bone-enclosed branches of the canal passed posteriorly to open amongst the ornamental ridges on the postero-lateral part of the bone ( S S C ~ - ~ , Figs 1 and 2). Another opening transmitted the epiphyseal branch into the median depression above the orbit (ssc5, Fig. 1). The parietal branch of the supraorbital canal, representing the termination of the canal and its continuation, the anterior pit-line, is not the longest and most medial of the posterior branches of the canal (ssc4, Fig. l), although this runs along the margin of the median depression on the skull roof, the normal position of the parietal branch in primitive teleosts, but is a more lateral branch (ssc3, Figs 1 and 2). From the opening of this latter branch a well marked, slightly curved groove (up& Figs 1 and 2) runs back on to the parietal, ending at the centre of radiation of the superficial ridges on the parietal. This groove usually ends just in front of the groove for the middle pit-line, but on one side of specimen P.51016 the two grooves are confluent. Sensory canals and pit-lines normally pass through or over the centres of ossification of the dermal bones with which they are associated (see, for example, Parrington, 1949), and the groove running back from the sensory canal pore on the frontal to the centre of radiation of the parietal must be the anterior pit-line, identifying the supraorbital sensory canal branch with which it is continuous as the parietal branch. The parietal branch and the anterior pit-line are displaced from their primitive position close to the mid-line as a consequence of lateral displacement of the parietals by the intervention of the supraoccipital (see further, p. 170).

Apart from this displacement of the parietal branch and anterior pit-line, the pattern of the supraorbital canal in Spratticeps, simple and largely bone enclosed, is very different from the condition in living clupeoids, which is highly modified. In Pornolobus (Tracy, 1920), Sardina (Wohlfahrt, 1937) and CZupea (Bamford, 1941) a sac-like expansion of a sensory canal fills the temporal foramen. Tracy did not describe the details of this canal, but in Surdina Wohlfahrt found it to be the central point of an independent system of branching canals, unconnected with the other sensory canals of the head. Wohlfahrt named the sac-like canal the sinus temporalis (‘bay-like expansion’-Tracy; ‘posterior dilatation’-Bamford), and called the independent system of which it is the centre the ‘Supratemporalsystem’. In Surdinu the ‘Supratemporal- system’ contains a single sense organ innervated by a recurrent branch of the facial

168 C . PATTERSON

FIGURE 4. Spratticepsgaultinus gen. et sp. nov. Reconstruction of the braincase in ventral view, c. x 8. For explanation of lettering see p. 182.


nerve having a common origin with the branch which innervates the uppermost sense organ of the preopercular canal; because of the innervation of its sense organ, Wohlfahrt concluded that the ‘Supratemporalsystem’ is a portion of the supraorbital

FIGURE 5 . Spratticeps gaultinus gen. et sp. nov. Reconstruction of the braincase in anterior view, as if cut through the centre of the orbitosphenoid, c. x 8. Sectioned surfaces hatched. For explanation of lettering see p. 182.

sensory canal which has become secondarily independent. In Clupea, Bamford (1941) found that the sinus temporalis develops as a hypertrophied posterior section of the supraorbital canal, to which it remains connected even in the adult, confirming Wohl- fahrt’s conclusion. Bamford held that the sinus temporalis represents the proximal

170 C . PATTERSON

sense organ of the anterior pit-line, which has become secondarily enclosed (he found the anterior pit-line of Clupea to be represented by a transverse row of four sense organs, leading medially from the sinus temporalis). However, since the anterior pit-line is only the continuation of the parietal branch of the supraorbital canal, there is no need to interpret the enclosure of the organ as secondary, and the sinus temporalis can be regarded as a hypertrophied parietal branch. The lateral position of the sinus temporalis and the transverse orientation of the anterior pit-line in Clupea are secondary: as shown above, this is due primarily to lateral displacement of the parietal, carrying the parietal branch and the pit-line with it. In Spratticeps this caused the parietal branch to lie over the temporal foramen (Figs 1 and 2), and when the roof of the post-temporal fossa was lost, exposing the temporal foramen, the parietal branch was already in position to occupy it. Lateral displacement of the parietal branch has given space for the hypertrophy of tubules from the epiphyseal branch of the supraorbital canal which is so characteristic of clupeoids (see Wohlfahrt, 1937, fig. 10; Bamford, 1941, fig. 5). The transverse orientation of the anterior pit-line in Clupea is probably due to its persisting relationship with the centre of ossification of the parietal, towards which it leads.

In Clupea, the middle pit-line is represented by a transverse row of about ten superficial sense organs lying immediately in front of the supratemporal commissure (Bamford, 1941, figs 4 & 7). This pit-line lies over a transverse groove on the parietal and supraoccipital. A similar groove is present in many clupeoids, such as Sardina (Wohlfahrt, 1937, fig, 2), Harengula, Potamalosa and Sardinella, and must correspond to the transverse groove in Spratticeps (mpl, Figs 1 and 2), from which it differs only in being less deeply incised and more irregular in its course, which is often slightly asymmetrical on the two sides of the head. In Sardina Wohlfahrt (1937) found this groove to contain not the middle pit-line but a main branch of the ‘Supratemporal- system’, containing no sense organs and connected with the sinus temporalis. That this canal represents a modified middle pit-line is indicated not only by exact topographical correspondence, but by Tracy’s observation (1920: 466) that in Pomolobus the ‘Supratemporalsystem’ is partially innervated by the supratemporal nerve (of glossopharyngeal and vagus origin), as is the middle pit-line. In Spratticeps, the transverse groove across the parietal and supraoccipital must have carried the middle pit-line, which was more deeply incised on the bone than it is in living clupeoids, and, as in Clupea, was unconnected with the supraorbital sensory canal, since it is clearly separated from the branches of the latter by intervening bony ridges. There can have been no sinus temporalis or specialized ‘Supratemporalsystem’ in Spratticeps, since the parietal branch of the supraorbital canal and the anterior pit-line, though laterally displaced, are otherwise unmodified, and since the temporal foramen, occupied in living clupeoids by the sinus temporalis, is still covered by the roof of the post-temporal fossa and is clearly separated from the parietal branch of the supraorbital canal.

The pterotic (Pto, Figs 2, 3 and 4) is incomplete in all specimens. It forms the posterior two-thirds of the hyomandibular facet (hmf, Fig. 4), meeting the prootic and sphenotic anteriorly, the posterior part of the wall of the dilatator, post-temporal and pre-epiotic fossae, bearing a ‘V’-shaped crest separating these three depressions


and meeting the parietal and epiotic above, and meets the prootic, intercalar and exoccipital on the ventro-lateral surface of the braincase. The external semicircular canal is enclosed within the pterotic, and is visible as a small swelling in the lower part of the pre-epiotic fossa (esc, Fig. 2). I n living clupeoids and in Denticeps the pterotic is a very complex bone, forming most of the wall of the recessus lateralis, receiving the temporal, preopercular, supraorbital, infraorbital and extratemporal sensory canals, and containing the pterotic bulla. In Spratticeps, although the superficial, sensory canal-bearing part of the pterotic is not preserved, it is evident that these structures were not present. There is no sign of a pterotic bulla (which passes through the arch of the external semicircular canal and expands above it: Tracy, 1920: 459; Wohlfahrt, 1936, fig. 28; Greenwood, 1968, fig. ll), even in specimens P.51017 and GSM 112223, where much of the inner face of the pterotic is exposed. In clupeoids the postero- lateral part of the supraorbital sensory canal, passing down into the recessus lateralis (which lies antero-ventral to the external semicircular canal), is carried within an extension of the frontal and lies well below the surface of the skull, underneath the crest separating the dilatator and post-temporal fossae (see, for example, Tracy, 1920, fig. 1 ; Wohlfahrt, 1937, figs 2 & 3). In Spratticeps this crest is partially preserved on the pterotic, and can only have carried a sensory canal superficially, as it does in Diplomystus brevissimus (Patterson, 1967, fig. 7). In D. brevissimus there is no recessus lateralis, the short, superficial portion of the temporal canal in the pterotic anastomos- ing with the preopercular canal posteriorly and with the supra- and infraorbital canals anteriorly. The anastomosis between the supraorbital, infraorbital and temporal canals in D. brevissimus lies at the junction of the frontal and pterotic, at the midpoint of the large dermosphenotic. Conditions in Spratticeps were probably much as in D. brevissimus: the presence of a large dermosphenotic is suggested by the large, flat dilatator fossa, and the pterotic must have carried a superficial sensory canal tube, missing in all specimens, which was ‘V’-shaped, as in D. brevissimus, and was attached to the V-shaped crest on the lateral surface of the bone. The temporal canal from the supratemporal entered at the apex of the hind limb of the ‘V’, the preopercular canal entered at the foot and the anastomosis with the infraorbital and supraorbital canals was at the apex of the front limb. The uninterrupted junctions of the pterotic with the prootic and sphenotic also show that there can have been no recessus lateralis, since this chamber is in communication with the cranial cavity between these three bones in dried skulls.

The epiotic (Epo, Figs 1, 2 and 3) is the usual conical bone, forming the postero- dorsal shoulder of the braincase, with a flat facet for the post-temporal on its upper surface. An antero-ventrally directed crest on the lateral surface of the epiotic forms the upper margin of the pre-epiotic fossa, and a groove below this crest leads into the foramen in the floor of this fossa.

The exoccipitals (Exo, Figs 1 , 2 , 3 and 4) are large and complex. They meet broadly above the foramen magnum (fm, Fig. 3), contacting the supraoccipital above and the epiotics dorso-laterally. Below the foramen magnum each exoccipital bears a large, postero-medially directed facet (Plate XD), covered by a centrum-like flange of the basioccipital forming the upper part of the occipital condyle. Immediately lateral to the foramen magnum and the exoccipital condyle there are two pitted facets, with

172 C . PATTERSON

a third lateral to the lower of these Cfim, Fig. 3). These facets probably served for the attachment of ossified ligaments ( ? intermuscular bones), as in Surdinops (Phillips, 1942: 470, fig. 6). There are two occipital nerve foramina Cfon, Fig. 3) one lying medial to the uppermost of the three facets, and one antero-dorsal to this facet. A small but clearly marked groove originates on the ventro-lateral surface of the exoccipital, just above the groove for the swimbladder, and passes up between the two lower facets on the hind face of the bone, turning medially above the uppermost of the three facets (gsu, Figs 3, 4). This groove probably contained the spinal artery (cf. Amiu, Allis, 1897: 710; and pholidophoroids, pers. obs.). On the ventro-lateral surface of the neurocranium the exoccipital meets the pterotic, intercalar, prootic and basioccipital, as usual. The vagus foramen (X, Figs 2 and 4) lies near the hind edge of the ventro- lateral surface of the exoccipital. The small glossopharyngeal foramen ( IX , Fig. 4) lies close in front of the vagus. Dorso-lateral to the vagus and glossopharyngeal foramina there is a third foramen (stf, Fig. 4), about equal in size to the glossopharyngeal, from which a shallow groove leads to a small foramen at the margin of the intercalar : these foramina and the groove mark the course of the supratemporal nerve. Lateral to the intercalar there is a group of minute foramina in the pterotic which may also have transmitted branches of the supratemporal nerve to the sensory canals. Below the vagus foramen there is a slit-like, postero-ventrally directed foramen, from which a groove leads back across the exoccipital on to the basioccipital Cfsb, gsb, Figs 2 and 4). This groove and foramen contained the cranial diverticulum of the swimbladder, passing up into the skull. Lateral to the vagus foramen there is an inconspicuous swelling (exb, Fig. 4) showing the characteristic pitted texture of clupeoid auditory bullae, which must be the exoccipital dilation or fusiform bulla of the swimbladder (cf. Tracy, 1920, fig. b ; Wohlfahrt, 1936, fig. 28). The exoccipital contained the greater part of the posterior semicircular canal, which is visible in lateral and posterior view (Plate 1 D ; psc, Figs 2 and 3) in the single specimen showing this region. Behind this canal there is an opening on the postero-lateral surface of the neurocranium as preserved, leading into an antero-medially directed cavity in the exoccipital. Probably this large opening is an artefact, but the cavity is real and seems to correspond to nothing in living clupeomorphs, in which the posterior semicircular canal always lies within the postero-lateral buttress of the braincase, not separated from this buttress by a cavity as it is in Spratticeps. There is some resemblance between this cavity and the subepiotic fossa (Phillips, 1942) of Surdinops and various other clupeoids, but the subepiotic fossa lies medial to the posterior semicircular canal, not posterior to it, is directed antero-laterally, not antero-medially, and is lined by the exoccipital and pterotic, not by the exoccipital alone. Possible explanations of this space between the posterior semicircular canal and the hind wall of the braincase will not be discussed in detail here, but it is worth noting that it recalls the conditions in palaeoniscoids and other fossil chondrosteans, in which the posterior semicircular canal is entirely contained within the anterior ossification of the neurocranium, being separated from the hind wall of the braincase by a space (the cranial fissure) and by the thickness of the occipital ossification (see Nielsen, 1942, 1949).

The basioccipital (Boc, Figs 1, 2, 3 and 4) forms the whole of the occipital condyle, a centrum-like dorsal expansion covering the exoccipitals, as in clupeoids, Megulops


and Osteoglossum. Anteriorly the basioccipital meets the prootics, both on the lateral surface of the skull and in the roof of the myodome. The myodome (myo, Figs 4 and 5) extends to the hind end of the basioccipital, where the divergence of its walls suggests that it opened posteriorly, as it does in most clupeoids, although it is impossible to be certain of this in the absence of the parasphenoid. Dorsally the basioccipital meets the exoccipitals and encloses the postero-lateral part of the saccular recesses.

The intercalar (Ic, Figs 2, 3 and 4), though small, is larger than in most clupeoids (the bone is absent in Denticeps). It covers the area of contact between the prootic,

‘i i

hmf

VI

sac

FIGURE 6 . Spratticeps gaultinus gen. et sp. nov. Sketch of the left prootic in ventral view (cf. Fig. 4), as if cut through horizontally at the level of the tube (tsb) transmitting the swimbladder diverticulum into the bulla. Radial fibres in wall of bulla indicated, other sectioned surfaces hatched.

sac, Saccular recess; utr, opening between bulla and utricular recess; for explanation of other lettering see p. 182.

pterotic and exoccipital, being partially overlapped itself anteriorly and laterally by flanges from the prootic and pterotic. Postero-laterally it projects in a raised knob for the attachment of the ventral limb of the post-temporal.

The most conspicuous feature of the prootics, and indeed of the whole neurocranium, is the very large prootic bullae (prb, Figs 2, 3, 4 and 5). Greenwood (1968: 228) comments on the large size of the prootic bullae in Denticeps as compared with Clupea. In Spratticeps the bulla seems to be about twice as big as that of Clupea, and shorter (rostro-caudally) but otherwise roughly equal in size to that of Denticeps. The walls of the bulla are thick (Fig. 6) and show the pitted surface and radial fibrous structure typical of clupeoid bullae. The two bullae almost meet in the mid-line in the prootic bridge (Figs 4 and S ) , partially occluding the antero-dorsal parts of the myodome and obliterating the anterior part of the saccular recess. As in Deizticeps and clupeoids

174 C . PATTERSON

there are two openings on the internal surface of the bulla (Fig. 6), one in the posterior surface which transmitted the swimbladder diverticulum back through a tube into the exoccipital, lateral to the saccular recess, and one lying postero-dorsally, leading into the utricular recess. The foramen of the abducens nerve (VI, Fig. 4) lies postero- medial to the bulla, in the roof of the myodome.

Dorso-lateral to the bulla, the prootic (Pro, Figs 2, 4 and 5) meets the sphenotic and pterotic and forms the antero-medial portion of the hyomandibular facet. Poster- iorly the prootic meets the exoccipital and basioccipital, overlapping these bones to some extent on the lateral surface of the skull. This postero-lateral surface of the prootic has a curious double structure, the outer layer of the bone ending well short of the prootic/basioccipital suture and forming a slight ridge with a small anteriorly directed pocket at its upper end (rpr, Figs 2 and 4). Among the skulls of living clupeoids that I have examined, only Chirocentrus shows anything similar, but here the ridge is higher on the prootic, although in much the same position relative to the prootic bulla (small in Chirocentrus). Presumably this ridge in Spratticeps marks the insertion of a connective tissue fascia, possibly the intercostal aponeurosis associated with the cranial diverticula of the swimbladder which Tracy (1920 : 450) described in Pornolobus. The lateral wall of the saccular recess is complete and there is no auditory fenestra: all living clupeomorphs have this fenestra at the junction of the prootic, exoccipital and basioccipital. The orbital surface of the prootic meets the pterosphenoid dorso- medially, the sphenotic dorso-laterally and the basisphenoid medially. Immediately above the orbital surface of the prootic bulla the bone contains two foramina, approx- imately equal in size, opening in a shallow recess (Fig. 5). The lateral foramen (fl, Figs 4 and 5) is the facial foramen, transmitting the hyomandibular trunk, the medial is the trigeminal foramen (tf, Figs 4 and 5), transmitting the mandibular and maxillary branches of the trigeminal nerve, probably with the buccal branch of the facial. Medial to the recess containing the facial and trigeminal foramina there is a smaller, ventrally directed foramen on the suture between the prootic and pterosphenoid (pf, Fig. 5); this probably transmitted the profundus nerve. From the facial foramen, the hyomandibular trunk turned ventro-laterally and passed back below a slender lateral commissure (damaged in all specimens but restored in Figs 2 , 4 and 5 , com) to reach the hyomandibular. The jugular vein also passed back below this commissure dorso- lateral to the bulla.

The sphenotic (S’o, Figs 2, 4 and 5) meets the prootic on the orbital and lateral surfaces of the braincase, contributes to the hyomandibular facet, and forms the greater part of the wall of the dilatator fossa, meeting the frontal above and the pterotic behind. Just above the anterior part of the hyomandibular facet there is a depression in the lateral face of the sphenotic, bounded above by a projecting flange (Zapf, Fig. 2), which is probably not part of the dilatator fossa but the site of origin of the levator arcus palatini muscle (cf. Denticeps, Greenwood, 1968, fig. 33; Scomber, Allis, 1903, pl. 5, fig. 11). The otic nerve emerged through a foramen (jot, Fig. 2) in the dilatator fossa just above the flange limiting the levator arcus palatini fossa. No entry foramen for the otic nerve could be found in the orbital surface of the sphenotic and the nerve may well have been bone enclosed throughout its course from the cranial cavity.

The basisphenoid (Bsp, Figs 4 and 5 ) is a small bone of complex shape, meeting the

-1 CLUPEOMORPH FISH FROM THE GAULT 175

pterosphenoids antero-dorsally and the prootics postero-ventrally. Except for a very small median ventral projection (Fig. 5)l there is no pedicel, as in other clupeomorphs. The hypophysial fenestra (hf, Fig. 4) i13 enclosed by the posterior part of the basisphenoid. The oculomotor foramen (111, Figs 4 and 5) lies within the lateral part of the basisphenoid, its outer margin formed by the prootic. Dorsally, the basisphenoid forms the lower margin of the optic fenestra (oft Figs 4 and 5), which is partially divided by a median process on the upper surface of the bone. This process is waisted near its base, probably for the passage of the optic nerves (11, Figs 4 and 5). A median foramen below the base of this process and a pair of small, laterally directed foramina (vf, Figs 4 and 5) above the oculomotor foramen are probably vascular.

The pterosphenoids (Pts, Figs 2, 4 and 5) contact each other for a short distance in front of the optic fenestra, and meet the orbitosphenoid anteriorly, the frontals and sphenotics laterally, and the prootics and basisphenoid posteriorly. The profundus foramen lies on the suture between the pterosphenoid and prootic, and just above this there is an antero-dorsally directed foramen (sof, Figs 2, 4 and 5) which must have transmitted the superficial ophthalmic nerves. In the upper part of the optic fenestra the pterosphenoid bears a notch or two short processes enclosing a groove, probably marking the passage of the trochlear nerve (IV, Figs 4 and 5).

Only the posterior part of the orbitosphenoid (Ors, Figs 2, 4 and 5) is preserved. As usual, it is V-shaped in section, meeting the frontals above and the pterosphenoids behind. A ventrally directed foramen in the centre of the lateral surface of the bone (acf, Figs 2 ,4 and 5) probably transmitted the anterior cerebral vein.

RELATIONSHIPS

Four specialized characters in the braincase of Spratticeps show that its closest relatives are to be found amongst the Clupeomorpha. These are the ear/swimbladder connection, the pre-epiotic fossa, the structure of the parietal and supraoccipital, and the temporal foramen. The most important of these is the ear/swimbladder connection, with a tube-like cranial diverticulum of the swimbladder entering the exoccipital below the vagus foramen, passing forwards through the exoccipital with a small dilatation surrounded by a rudimentary bulla en route, and ending in a very large prootic bulla. The prootic bulla is responsible for peculiarities in the course of the hyomandibular nerve, which emerges in the orbit and passes posteriorly below the lateral commissure, and probably also in the course of the orbital artery and palatine nerve, which penetrate the prootic in most primitive teleosts but which cannot be traced in Spratticeps. There is no pterotic bulla in Spratticeps. A pterotic bulla is present in Denticeps, and among clupeoids it seems to be absent only in Sprattus and Clupeonella (Svetovidov, 1952 ; Whitehead, 1964). Regarding Sprattus and Clupeon- ella Whitehead (1964: 328) writes ‘whether the absence of this bulla is a primitive condition or is due to subsequent loss is an open question. If the latter, then it may have occurred independently in the two genera, which might explain the apparent relationship of Clupeonella to the Sardina-Surdinella group’. As is clear from comments in Whitehead’s paper, the characters on which phylogenetic relationships amongst clupeids are at present estimated are too few and too poorly known for any reliable

176 C . PATTERSON

conclusions to be reached. But since Denticeps, which has a pterotic bulla, is found on other grounds to be the plesiomorph sister group of the clupeoids (Greenwood, 1968: 271), it is more reasonable to regard the absence of the pterotic bulla in Sprattus and Clupeonella as due to secondary loss than to hypothesize independent acquisition of pterotic bullae in clupeoids and denticipitoids. In Spratticeps, which in several characters is more primitive than either clupeoids or denticipitoids, it is reasonable to regard absence of a pterotic bulla as a primitive feature. The development of a pterotic bulla appears to be merely a refinement of a system already established by the relationship between the swimbladder and the utriculus in the prootic bulla (Wohlfahrt, 1936). The late appearance, in ontogeny, of the pterotic swimbladder diverticulum and bulla (de Beer, 1937: 134) also supports this conclusion.

The pre-epiotic fossa of Spratticeps, though small, is evidently identical in structure with that of clupeoids. Where there is no pre-epiotic fossa in clupeomorphs, as in Denticeps and Coilia (Ridewood, 1905:477), there is evidence that this is a derived condition associated with inflation of the braincase or enlargement of the pterotic bulla. This point, and the presence of a large pre-epiotic fossa with an opening on the skull roof in the Cretaceous Diplomystus brevzkimus, support interpretation of the condition in Spratticeps as indicating that a pre-epiotic fossa is a primary feature of the clupeomorph braincase. The function of the pre-epiotic fossa is unknown. When large it is filled by trunk musculature, but the small foramen in Spratticeps can have had only minimal value as a site for muscle insertion. The wide variation in the size of the fossa in clupeomorphs and its occasional absence do not indicate that it is of great importance in the life of these fishes. It is possible that the fossa is only a primitive actinopterygian feature, without evident function (like urodermals, caudal scutes, pectoral and pelvic splints, etc.). If so, it should have a homologue in the braincase of early actinopterygians. The pre-epiotic fossa passes medially through the arch of the posterior semicircular canal. It seems always to be closed towards the cranial cavity, if only by cartilage. In a few forms, evidently advanced, it becomes confluent with the subepiotic fossa on the hind face of the skull. No such structure has been found in leptolepids or pholidophorids (Rayner, 1937, 1948; pers. obs.). In Kentuckia, perhaps the most primitive actinopterygian in which the braincase is known, there is a foramen (Rayner, 1951, fig. 7, intm. ch.) corresponding in position and size with the pre-epiotic fossa of Spratticeps. This foramen leads to an irregular chamber in the wall of the neurocranium which opens into one of the pits representing the fossa bridgei on the roof of the braincase. According to Rayner (1951: 78) this chamber is probably in part homologous with the deep posterior part of the fossa bridgei in later palaeoniscoids (Kansas palaeoniscids A-C, Pteronisc2slus, Boreosomus, Perleidus), which in Pteroni- sculus and Boreosomus is in communication with the cranial cavity, apparently because of reduction in the thickness of the cranial wall. In holosteans, the lateral cranial canal in Caturus (Aldinger, 1932: 16; Rayner, 1948: 299) and Dapedium (Rayner, 1948 : 308) is in turn partially homologous with the fenestra between the fossa bridgei and the cranial cavity, here sunk within the wall of the braincase and with no external opening. Thus if one searches among early actinopterygians for a homologue of the clupeomorph pre-epiotic fossa, it is only in the most primitive form known, Kentuckia, that there is any close similarity, later palaeoniscoids and holosteans showing modi-


fications in other directions. This chain of homologies, based only on topographical similarity, seems too tenuous for any conclusion to be drawn.

In Spratticeps, as in Denticeps and all clupeoids, the parietals are separated by the supraoccipital and the medial part of the supratemporal commissural sensory canal traverses these bones, not separate extrascapular bones. This must indicate that in all these fishes canal-bearing median and lateral extrascapular elements have fused with the supraoccipital and parietals respectively. Alternative interpretations, that the extrascapulars have ‘replaced’ the parietals and supraoccipital or that the parietals and supraoccipital have ‘captured’ the supratemporal commissure, are both improbable, the first because the supraoccipital has endochondral portions and the parietal bears the middle and anterior pit-lines and has normal relations with the surrounding bones (see also Weitzman, 1962: 22), the second because the supraoccipital is originally and primarily a cartilage bone having no association with a sensory canal, and can only acquire a canal-bearing component by fusion with some dermal bone. This fusion of the extrascapulars with the parietals and supraoccipital must have occurred very early in the history of clupeomorphs and is a primary feature of the group (I doubt whether it would be helpful to emphasize this by referring to these bones as ‘parieto- extrascapular’ and ‘supraoccipito-extrascapular’ in all clupeomorphs). Separation of the parietals by the supraoccipital in clupeomorphs did not develop by gradual enlargement of the supraoccipital as it did, for example, in various euteleostean lineages, but is simply a consequence of fusion with a median dermal extrascapular. In having the supraoccipital portion of the supratemporal commissure bone enclosed, Sprat- ticeps is more primitive than living clupeomorphs, all of which have the commissure superficial to the supraoccipital. According to Daget (1965 : 272), Phractolaemus is the only living teleost in which the supraoccipital is penetrated by the supratemporal commissure.

The post-temporal fossa of Spratticeps, though roofed to a greater extent than in living clupeomorphs, has the characteristic clupeomorph temporal foramen at its apex, bounded by the frontal and parietal. Although many other teleosts have membranous fenestrae or areas of cartilage in the medial wall of the post-temporal fossa, these always seem to be bounded in part by endochondral bone, and none corresponds exactly with the temporal foramen, excavated in dermal bone. Since the foramen lies in dermal bones which have secondarily sunk inwards and become covered by trunk musculature it is certainly an advanced character, a primary feature of clupeomorphs. At present, nothing can be said on the possible origin of the structure. Bamford (1941 : 433) has speculated on its function in living clupeoids, where it is occupied by the sinus temporalis.

Apart from these four clupeomorph features, the braincase of Spratticeps is more primitive than those of living clupeomorphs in several ways. Evidently there was no recessus lateralis, as in the Upper Cretaceous Diplomystus breaissimus. A recessus lateralis is present in all living clupeoids, and that of Denticeps differs only in having no separate opening for the supraorbital sensory canal. The considerable structural changes involved in the evolution of the recessus lateralis, of which the most obvious is reduction of the primitively large dermosphenotic, must have taken place in the late Cretaceous or very early Tertiary, in the common ancestor of the denticipitoid and

13

178 C . PATTERSON

clupeoid lines. There is no sinus temporalis in Spratticeps, but the posterior part of the supraorbital canal is modified by lateral displacement of the parietal branch and the anterior pit-line, so that the parietal branch ends above the temporal foramen, a preadaptation towards the development of a sinus temporalis when the temporal foramen becomes exposed by reduction in the roof of the post-temporal fossa. A sinus temporalis is probably present in all clupeoids : it has been reported in Clupea, Sardina, Pomolobus, Alosa and Brevoortia, and the identical structure of the temporal foramen in other clupeoids suggests that it is filled by a sinus temporalis, as it is in all those that have been investigated. In Dentice$s, where the temporal foramen has a slightly different structure, lying entirely within the frontal and being overhung by an upper flange of the bone, Greenwood (pers. comm.) was unable to find a sinus temporalis, suggesting that the structure is characteristic only of the clupeoid lineage. In Diplomy- stus there was evidently no sinus temporalis, since the post-temporal fossa is still partially roofed, the temporal foramen is not exposed, and the parietal branch of the supraorbital canal is unmodified.

An auditory fenestra, present in all living clupeomorphs, is absent in Sprutticeps and also in Diplomystus brevissimus (Patterson, 1967: 103). The auditory fenestra is without obvious function (cf. Wohlfahrt, 1936), and its absence in Spratticeps and Diplomystus may be only a consequence of the heavier ossification of the skull in these early forms: in Spratticeps the pronounced ornament of the skull roof, the bone enclosed sensory canals, the strong impression of the middle pit-line on the parietal and supraoccipital and the close bony investiture of the nerves and blood vessels in the orbito-temporal and occipital regions seem to be all primitive characters due to more complete ossification of the skull than in living forms, this heavy ossification itself being a primitive condition, as is indicated by comparison with palaeoniscoids and pholidophoroids. Other primitive characters of Spratticeps include the absence of a pterotic bulla, the small pre-epiotic fossa, the rather large intercalar and the partially roofed post-temporal fossa. This last feature is shared with Diplomystus, but the posterior part of the skull roof in Sprutticeps is much more primitive than that of Diplomystus, which is considerably modified by forward extension of the trunk musculature, presumably as a consequence of the deep, compressed trunk.

Greenwood (1968: 271) sees the living clupeomorphs as comprising two suborders, Denticipitoidei and Clupeoidei, the first being the plesiomorph sister group of the second. Denticeps shows several unique specializations, especially the development of odontodes on all the external dermal bones, but in other ways it is more primitive than clupeoids, notably in the structure of the recessus lateralis, the absence of a sinus temporalis (above), the complete lateral line, the caudal skeleton, and possibly also in the tripartite occipital condyle (see below) and the simple intermuscular bones (parenthetically, Greenwood writes that the absence of epineurals in Denticeps should be considered primitive, but conditions in pholidophoroids, where epineurals only are present, indicate that it is advanced). The braincase of Denticeps differs from those of clupeoids chiefly in having a very large prootic bulla and no pre-epiotic fossa, dilatator fossa, post-temporal fossa or intercalar. The very large prootic bulla of Spratticeps resembles that of Denticeps, but this is doubtfully significant. The other features of the braincase of Denticeps are all probably advanced (see above) and are


not found in Spratticeps. The clupeoid braincase is advanced over that of Denticeps in the structure of the recessus lateralis and, according to Greenwood, in having the occipital condyle formed entirely by the basioccipital, as it is in Spratticeps. Regarding the occipital condyle, Greenwood (1968 : 233) draws attention to Ridewood’s statement (1904 : 64) that in many lower teleosts a ‘half-centrum’ is fused with the basioccipital and exoccipitals, and can be removed ‘by the application of some force’ to expose the inverted Y-shaped suture of the primitive tripartite occipital condyle, which forms the articular surface in Salmo, Hiodon, Heterotis, the Jurassic Anaethalion (Nybelin, 1967), and various other primitive teleosts. However, despite Ridewood’s opinion, it seems very unlikely that a ‘half-centrum’, removable by any amount of force, is fused with the basioccipital in Spratticeps or, indeed, in clupeoids. Further, in Leptolepis and Pholidophorus the occipital condyle is formed entirely by the basioccipital, as in Spratticeps and clupeoids (pers. obs.). The significance of these variations is not yet clear, but certainly the situation does not seem to be so simple as Ridewood supposed, with opposition between a primitive tripartite occipital condyle and an advanced basioccipital condyle, with or without incorporation of vertebral material.

There is thus no good evidence for aligning Spratticeps with either the denticipitoid or clupeoid lineages, and it can only be placed near the common ancestry of the two, or as the plesiomorph sister group of the two combined. The position of Diplomystus in such an arrangement is also doubtful, since on present knowledge there are very few points on which it can be compared with Spratticeps. In comparison with Spratticeps the braincase of Diplomystus seems to be advanced towards the clupeoid condition in the large pre-epiotic fossa, and more advanced than Spratticeps in the rather large supratemporal fossa. On the other hand, it seems improbable that Diplomystus brevissimus could have had a prootic bulla of the size of that of Spratticeps, for there is no sign of such a structure in many specimens prepared in acid. Resem- blances between Diplomystus and Spratticeps (no recessus lateralis, sinus temporalis or auditory fenestra, post-temporal fossa partially roofed, skull roof with strong ornament) are all in primitive characters, and at present there is no good reason for placing Spratticeps in Greenwood’s (1 968 : 265) family Diplomystidae, unless this is used purely as a paraphyletic basal clupeomorph group. Until other parts of the skeleton of Spratticeps are known, it seems best to leave it as Clupeomorpha incertae sedis.

CLUPEOMORPH CHARACTERS

Regarding the characterization of the Clupeomorpha, Spratticeps shows that the primary cranial characters of the group do not include the recessus lateralis or several other features listed by Greenwood et al. (1966: 350) but are:

(i) A swimbladder/ear connection involving penetration of the exoccipital and prootic, with the development of a bulla in the prootic.

(ii) Fusion of median and lateral extrascapulars with the supraoccipital and parietal, resulting in enclosure of the supratemporal commissure within these bones, separation of the parietals by a dermal part of the supraoccipital, and lateral

180 C . PATTERSON

displacement of the parietal branch of the supraorbital canal and the anterior pit-line.

(iii) Development of a fenestra, the temporal foramen, between the frontal and parietal in the apex of the post-temporal fossa.

A fourth cranial character, the presence of a pre-epiotic fossa, is also characteristic of clupeomorphs, but whether or not this is an advanced character is uncertain in view of the possible homology between this cavity and an intramural chamber in the neurocranium of various chondrosteans and holosteans (p. 176).

The earliest known clupeomorphs are Clupea antiqua Pictet (1858: 31, pl. 4, figs 7-13) and C. voironmis Pictet (1858: 37, pl. 5, figs 1-10), both from the Calcaire des Hivernages, Voirons, Switzerland, which is of Hauterivian (Upper Neocomian) age, pre-dating Spratticeps by a considerable period. These species, known by several crushed but more or less complete fishes, have not been redescribed since Pictet’s work, which, although excellent for its time, is of little value for detailed comparisons. Pictet interpreted the genus Clupea in a wide sense and considered C. antiqua to be close to Alosa, C . voironensis to Clupea s. str., but the characters on which such assignments could be made are not visible in the specimens. C. antiqua, however, has ventral scutes of typical clupeoid type, with long ascending arms. Although these scutes are not fully convincing as evidence of clupeomorph affinities, other features of these fishes, especially the form of the maxilla and the scales, suggest that Pictet was essentially correct in his placing of them, and that the presence of large abdominal scutes (also present in the Cretaceous diplomystids) should be added to the cranial characters listed above as a primary clupeomorph feature. Further information on the caudal skeleton of the two Neocomian species is highly desirable, but in its absence the caudal skeleton of Diplomystus (Cavender, 1966, fig. 4; Patterson, 1967, fig. 8; Greenwood, 1968, fig. 32) must be taken as the most primitive known amongst clupeomorphs. This has only six hypurals, the first tapered proximally, the second fused with the first ural centrum and very slender, the third much expanded. There are three uroneurals, the first two elongate and reaching the first pre-ural and ural centra respectively, three epurals, a full neural spine on the second pre-ural centrum and a short neural spine on the first. The most important specialisations of this caudal skeleton are the reduction of the proximal part of the first hypural and fusion of the second with the first ural centrum: these must also be interpreted as primary clupeomorph characters.

SUMMARY

A primitive clupeomorph fish, Spratticeps gaultinus gen. et sp. nov., is described on the basis of incomplete braincases from the Gault (Albian) of Folkestone, Kent. This is the earliest clupeomorph in which any details of cranial structure are known. Spratticeps had a cranial diverticulum of the swimbladder ending in a very large prootic bulla, a small pre-epiotic fossa, a temporal foramen in the apex of the post- temporal fossa, and median and lateral extrascapulars fused with the supraoccipital and parietals, resulting in enclosure of the supratemporal commissure within these bones, separation of the parietals by the supraoccipital, and lateral displacement of

A CLUPEOMORPH FISH FROM T H E GAULT 181

the parietal branch of the supraorbital sensory canal and the anterior pit-line. Sprat- ticeps is more primitive than living clupeomorphs in having no recessus lateralis, auditory fenestra, pterotic bulla or sinus temporalis, and in having a heavily ornamented, entire skull roof, with the sensory canals bone enclosed and the post-temporal fossa roofed. The fish is too primitive to be placed in either suborder of Clupeomorpha, and is left incertae sedis. The primary characters of the Clupeomorpha are discussed.

REFERENCES

ALDINGER, H. A., 1932. uber einen Eugnathiden aus der unteren Wolgastufe von Ostgronland. Meddr Grenland, 86, 4: 1-51.

ALLIS, E. P., 1897. The cranial muscles and cranial and first spinal nerves in Amia calva. y. Morph., 12: 487-808.

ALLIS, E. P., 1903. The skull, and the cranial and first spinal muscles and nerves in Scomber scomber. J . Morph., 18: 45-328.

BAMFORD, T. W., 1941. The lateral line and related bones of the herring (Clupea harengus L.). Ann. Mag. nut. Hist., (11) 8: 414-438.

DE BEER, G. R., 1937. The Development of the Vertebrate Skull. xxiv + 552 pp., 143 pls.:Oxford; Claren- don Press.

CAVENDER, T., 1966. The caudal skeleton of the Cretaceous teleosts Xiphactinus, Zchthyodectes and Gil- licus, and its bearing on their relationship with Chirocentrus. Occ. Pup. Mus. 2001. Univ. Mich., 650: 1-15.

CHAPMAN, W. McC., 1948. The osteology and relationships of the round herring Etromws micropus Temminck & Schlegel. Proc. Culij. Acad. Sci., (4) 26: 25-41.

DAGET, J., 1965. Le crane des TClCostCens. MLm. Mus. natn. Hist. nut. Paris, (A) 31: 163-341. GREENWOOD, P. H., 1968. The osteology and relationships of the Denticipitidae, a family of clupeo-

GREENWOOD, P. H., D. E. ROSEN, S. H. WEITZMAN & G. S. MYERS, 1966. Phyletic studies of teleostean

NELSON, G. J., 1969. Gill arches and the phylogeny of fishes, with notes on the classification of verte-

NIELSEN, E., 1942. Studies on Triassic fishes from East Greenland. I. Glaucolepis and Boreosomus.

NIELSEN, E., 1949. Studies on Triassic fishes from East Greenland. 11. Australosomzts and Birgeria.

NYBELIN, O., 1967. Versuch einer taxonomischen Revision der Anaethalion-Arten des Weissjura Deuts-

PARRINGTON, F. R., 1949. A theory of the relations of lateral lines to dermal bones. Proc. zool. Soc.

PATTERSON, C., 1967. Are the teleosts a polyphyletic group ? Colloques int. Cent. natn. Rech. sdent., 163:

PHILLIPS, J. B., 1942. Osteology of the Sardine (Sardinops caerulea).J. Morph., 70: 463-500. PICTET, F. J., 1858. Description des poissons fossiles du terrain NCocomien des Voirons; 54 pp., 7 pls.

RAYNER, D. H., 1937. On Leptolepis bronni Agassiz. Ann. Mag. nat. Hist., (10) 19: 46-74. RAYNER, D. H., 1948. The structure of certain Jurassic holostean fishes, with special reference to their

RAYNER. D. H.. 1951. On the cranial structure of an early palaeoniscid, Kentrrckia, gen. nov. Trans. R.

morph fishes. Bull. BY. Mus. nut. Hist. (Zoo[.), 16: 213-273.

fishes, with a provisional classification of living forms. Bull. Am. Mus. nut. Hist., 131: 339456.

brates. Bull. Am. Mus. nut. Hist., 141: 475-552.

Meddr Grsnland, 138: 1-403.

Afeddr Grsnland, 146: 1-309.

chlands. Acta R. SOC. Scient. Zitt. gothoburg., Zool., 2: 1-53.

Lond., 119: 65-78.

93-109.

SCr. 2, no. 1, pt. 3. In Materiauxpour la PalPontoIogie Suisse. Genhve: J . G. Fick.

neurocrania. Phil. Trans. R. Soc., ( B ) 233: 287-345. . - , -

S O ~ . i d i d . , 62: 53-83. RIDEWOOD, W. G., 1901. On the cranial osteology of the fishes of the families Elopidae and Albulidae,

with remarks on the morphology of the skull in the lower teleostean fishes generally. Pror. zoo[. Soc. Lond., 1904, 2 : 35-81.

RIDEWOOD, W. G., 1905. On the cranial osteology of the clupeoid fishes. Proc. zool. Soc. Lond., 1904, 2: 448493.

SVETOVIDOV, A. N., 1952. Clupeidae. Opred. F a m e SSSR, (N.S.) 48 2, 1 : 1-331. TRACY, H. C., 1920. The clupeoid cranium in its relation to the swim-bladder diverticulum and the

WEITZMAN, S. H., 1962. The osteology of Brycon meeki, a generalized characid fish, with an osteological

WHITEHEAD, P. J. P., 1963. A contribution to the classification of clupeoid fishes. Ann. Mag. mt. Hist.,

membranous labyrinth. r. Morph., 33 : 439-483.

definition of the family. Stanford ichthyol. Bull., 8: 1-77.

(13) 5 : 737-750.

182 C. PATTERSON

WHITEHEAD, P. J. P., 1964. A new genus and subgenus of clupeid fishes and notes on the genera Clupea,

WOHLFAHRT, T. A., 1936. Das Ohrlabyrinth der Sardine (Clupea pilchardus Walb.) und seine Bezie-

WOHLFAHRT, T. A., 1937. Anat+sche Untersuchungen iiber die Seitenkaniile der Sardine (Clupea

Sprattus and Clupeonelkz. Ann. Mag. nat. Hist., (13) 7: 321-330.

hungen zur Schwimmblase und Seitenlinie. Z. Morph. dkol. Tiere, 31: 371-410.

pilchardus Walb.). Z. Morph. Okol. Tiere, 33: 381-411.

EXPLANATION OF PLATE

PLATE 1 S’utficepsguulfinus gen. et sp. nov. The holotype, BM(NH) No. 3631 1, in A, dorsal view; B, ventral view; C, right lateral view; D, posterior view. x 8.

ABBREVIATIONS USED I N FIGURES

foramen of anterior cerebral vein groove for anterior pit-line basioccipital basisphenoid cranial cavity outline of temporal foramen lateral commissure dilatator fossa epiotic external semicircular canal exoccipital bulla exoccipital facial foramen facets for ossified ligaments on exoccipital foramen magnum foramina of occipital nerves exit foramen of otic nerve frontal foramen for entry of cranial diverticulum of swimbladder groove for spinal artery groove for cranial diverticulum of swimbladder hypophysial fenestra hyomandibular facet intercalar levator arcus palatini fossa groove for middle pit-line myodome optic fenestra

Ors Pa Pef Pf Prb Pro P S C P?f Pto Pts rPr

SOC sof

SPO ssc, ssc1-

stc

S t f StP tf .f 11 111 IV V I I X X

orbitosphenoid parietal pre-epiotic fossa profundus foramen prootic bulla prootic posterior semicircular canal post-temporal fossa pterotic pterosphenoid ridge on prootic for attachment of connective tissue fascia supraoccipital foramen of superficial ophthalmic nerves sphenotic

. 5 r cavity for, entry foramen of, and pores for branches of supraorbital sensory canal foramen for entry of supratemporal commissure foramen of supratemporal nerve pores of supratemporal commissure trigeminal foramen small vascular foramina in basisphenoid passage of optic nerve oculomotor foramen passage of trochlear nerve abducens foramen glossopharyngeal foramen vagus foramen

a clupeomorph fish from the gault (lower cretaceous)

Documents