AN UPPER CRETACEOUS ORNITHOPOD FROM NEW ZEALAND

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J. WIFFEN* & R.E. MOLNAR**

ABSTRACT

The partial ilium of a Dryosaurus-like ornithopod dinosaur has been discovered in the Upper Cretaceous Maungataniwha Sandstone of North Island, New Zealand. This is the first orni- thischian dinosaur from New Zealand. At the time this animal lived, New Zealand was near the Ross Sea region of Antarctica, near 60 degrees S. latitude. This occurrence suggests such di- nosaurs were capable of living in polar regions and may have lived in Antarctica itself.

R~SUM~

L'ilion partiel du Dryosaurus semblable ~ celui d'un dino- saurien ornithopode a dt4 ddcouvert dans les gr~s Maungatani- wha du Cr6tac6 supErieur de l'tle du Nord de la Nouvelle-Z6- lame. C'est le premier dinausaurien ornithischien de Nou- velle-Zdlande. A l'6poque ~. laquelle cet animal a v&u, la Nou- velle-Zdlande 6tait la mer de Ross dans la r6gion Antarctique, peu pros ~. la latitude de 60 degr6s Sud. Cette pr6sence suggbxe que des dinosauriens semblables 6talent susceptibles de vivre dans des rdgions polaires et ont peut-~tre m~me v4cu en An- tarctique.

KEY-WORDS : D~NOSAURIA (ORNITHOPODA), UPPER CRETACEOUS, NEW ZEALAND, ANTARCTICA, ILIUM, MAUNGATANIWHA SANDSTONE. MOTS-CLI~S : DINOSAURIA (ORNITHOPODA), CRI~TACI~ SUPI~RIEUR, NOUVELLE-ZI~LANDE, ANTARCTIQUE, ILION, FORMATION MABNGATANIWHA.

* 138 Beach Road, Haumoana, New Zealand ** Queensland Museum, P.O. Box 300, South Brisbane, Queensland, Australia, 4101

Geobios n ° 22, fasc. 4 p. 531-536, 3 fig. Lyon, aofit 1989

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INTRODUCTION

Continuing exploration for vertebrate fossils in the marine Upper Cretaceous Mata Series at Mangahouanga Stream on North island, New Zealand (Wiffen 1980), has yielded an in- complete ilium of an ornithopod dinosaur. This ilium repre- sents the second undoubted dinosaur from New Zealand (Mol- nar 1981), and the first which can be recognised at the level of Family. The Mata Series includes the informally named Maun- gataniwha Sandstone (Moore 1987) of Piripauan-Haumurian age (equivalent to Campanian-Maastrichtian : Wellman 1959). It is from the upper part of the Maungataniwha Sandstone, which consists of apparently poorly bedded sandstones with calcareous concretions (Moore 1987), that the ilium derives.

The Maugataniwha Sandstone was deposited on the conti- nental shelf of North Island, apparently under shallow, near- shore conditions. In addition to many invertebrate taxa, a ver- tebrate fauna of marine reptiles (Wiffen 1980, 1981 ; Wiffen & Moisley 1986) and fishes (Keyes 1977 ; Wiffen 1983) is known. Two elements from terrestrial forms have been recovered (Mol- nar 1981 ; Scaflett & Mollnar 1984). In February 1987 the or- nithopod ilium was recovered from this locality, grid reference NZMS 260 V19/420469, New Zealand Fossil File locality V19/F6909. This represents the first certain ornithopod dino- saur from New Zealand.

DESCRIPTION

This specimen, CD529, consists of the posterior portion of an ilium broken vertically at the acetabulum (fig. 1). It is un- crushed and, except for the absence of the anterior moiety, es- sentially undamaged. The specimen may be confidently identi- fied as an ilium from both its general form and the following distinctive features : 1) ischial peduncle, 2) thin dorsal blade, 3) medial blade (brevis shelf), and 4) scars for sacral ribs. As preserved the ilium is 102 mm long, and 59 mm deep at the is- chial peduncle. At its posterior termination the postacetabular blade is 72 mm high and has a maximum width (as preserved) of 40 mm : a small portion of the medial margin is absent pos- teriorly. The tuberosity at the posterior end of the blade, and the lateral tuberosity of the ischial peduncle, as well as its si- milar overall form, suggest that it derives from a hypsilopho- dontian ornithopod.

A

B

Fig. I - Posterior portion of an ornithopod ilium found a t Mangahouanga Stream, western t Iawkes Bay dis t r ic t , North Island, New Zealand. A, lateral aspect ; B, medial aspect ; C, dorsal aspect.

Pa t t i e p o s t g r i e a r e d 'un i l ion d 'o rn i thopode t rouv6 prb.s du fleuve Mangahouanga, fi I 'oues t de la Baie de IIawkes, l ie du Nord de la Nouvel le . -Z6lande. A, rue [at6rale ; B, rue interm6diaire ; C, rue dorsale.

C

~x~ ~ ~i !!i~i~ii ~ ~

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IL

P T .

A B IL

M B " : . : . : . . ,

G D MB

~.~" ..-... "".',:'2-~ ~.',:v..., :-.- . .... ~ : ' ; ~ > ....... ~ ,..,.~:"::'::',(!::@

F T ~ ~ ' P T

Fig. 2 - Posterior portion of Mangahouanga Stream ornithopod ilium (A, D, F) compared with ilium ofDryosaurus lettolrvorbecki (B, C, E). A, B, lateral as- pect ; e, D, medial aspect ; E, F, dorsal aspect. A brevis sheft much broader than those of other ornithopods is shared, but the gvo differ in the form and elevation of that shelf, il, blade of ilium, it, tuberosity of ischial pedunclef rob, medial blade ; pt, posterior tubercle ; st', scars for sacral ribs. Scale 5 cm.

Partie post6rieure d'un ilion d'ornithopode trouv~ pros du fleuve Mangahouanaga (A, D, F) compar(~e ,1 l'ilion de l?ryosaurz~s lettowvorbeckt (13, C, I~). A, B, rue latfrale ; C, D, me interm6diaire et E, F, vue dorsale. L'apophyse pour le muscle caudifemoralis brevis est beaucoup plus large que cdles des autres orni- thopodes mais les deuax diff&ent dans la forme et l'616vation de cette apophyse, il, cr&e iliaque ; iL tub6rosit6 de post&ieur ; sr, surface articulaire des c~tes sacr&s. Echdle 5 cm.

COMPARISON

Such a form is not found in other ornithopods, such as iguanodontids, hadrosaurids, or lambeosaurids. Hadrosaurid and lambeosaurid ilia show an antitroehanter and elongate postacetabular process, features absent in this specimen. Igua- nodontid ilia also show an elongate, but shallower, postaceta- bular process as weU as a thickening of the dorsal margin ab- sent in this specimen. The length, depth and general form of the postacebular region are unlike any known from ceratop- sians, saurischians, crocodilians, lacertilians, mossaurs or ple- siosaurs. The stegosaur ilium has an antitrochanter, while that of the ankylosaurs differs in the rim along the dorsal margin. Considering these particular differences, together with those of

general form, this specimen is tentatively assigned to the Dryo- sauridae. The recent and continuing studies of the phytogony of ornithopods (Maryanska & Osmolska 1985 ; Norman 1985 ; Sereno 1986) suggest the desirability of not yet regarding any ornithopod classification as generally accepted, and hence, in accordance with this view and the incomplete nature of the material found at Mangahouanga we make this assigment ten- tative.

The closest match In overall form is to the ilia of the dryo- saurids (Janensch 1955 ; Galton 1981 ; Galton & Taquet 1982), especially to the configuration of the posterior termination of

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the iliac blade in lateral aspect, and of the brevis shelf in dor- soventral aspect (fig. 2). The ratio of width to height of the pos- terior moiety of the dryosaur ilium is greater than 2. That ratio for "all other hypsilophodontids, Camptosaurus, Tenontosau- rus and Tbesce[osaurus" (Galton 1981, is less than 1/2. In the Mangahouanga ilium this ratio is now almost 2, and taking into account that the brevis shelf is slightly incomplete medially, for the complete ilium this ratio was likely 2 or slightly greater. This clearly suggests a relationship to Dryosaums. The Manga- houanga ilium, however, differs from those of Dryosaums in the following points : 1) more pronounced and abrupt lateral projection of the posterior tubercle, 2) less pronounced and abrupt medial extent of the medial shelf, and 3) medial shelf at the ventral margin of the posterior blade, rather than closer to the dorsal than to the ventral margin (fig. 2). The me-

dial shelf is at the ventral margin in at least one of the ilia re- ferred to VaMosaurus canalic,datus (Galton & Taquet 1982, fig. 21). The New Zealand specimen is more similar to the smaller of the two specimens discussed by Galton & Taquet. But there are distinctions : 1) the dorsal portion of the poste- rior tubercle is more acute in posterior view, 2) the dorsal margin is thinner in the Mangahouanga ilium, and 3) the tu- bercle of the ischial process is deeper and transversely wider. The great temporal and spatial separation of the New Zealand specimen from known occurrences of dryosaurs indicates that the Mangahouanga ilium cannot be referred to this taxon. Al- though it almost certainly represents an otherwise unknow or- nithopod genus and species, we prefer not to erect a new gene- ric and specific name unless further and more complete mate- rial comes to light.

DISCUSSION

About 80 million years ago New Zealand separated from the Ross Sea region of Antarctica (Cooper et alii 1982). During the time of deposition of the Mata Series, New Zealand was located near 60 degrees S. latitude, just off the coast of Antarctica. Thus this occurrence, of the fourth hypsilophodontian locality from the southern hemisphere (the others are that of Kangna- saurus in Namagaland, southern Afl.ica, that of Fulgurotbe- rium at Lightning Ridge, New South Wales, Australia, and that of several taxa along the southern coast of Victoria, Australia), extends the known range of hypsilophodontian ornithopods to

C °

Fig. 3 - Map of the southern continents during the Upper Cretaceous (mo- dified after Zinsmeister's (1987) map for the mid-Cretaceous) showing An. tarctic and near-Antarctic Cretaceous dinosaur localities. Upper Creta- ceous localities : A, Malagahouanga Stream, New Zealand (?dryosaur) ; B, James Ross Island (ankylosaur). Lower Cretaceous localities : C, Lightning Ridge, New South Wales, Australia (hypsilophodontians, ?iguanodontoid, theropods, ?sauropod) ; D, Cape Otway region, Victoria, Australia (hypsilo- phodontians, theropods) ; E, Cape Faterson region, Victoria, Australia (hypsilophodontians, theropods). Both Upper and Lower Cretaceous loca- lities further from the Antarctic Circle are known in South America, but not shown here.

Carte pal6og6ographlque des continents sud au Cr~ta¢6 sup6rieur (modifi6e d'apr~s Zinsmeister (1987) carte pour le Cr6tac6 moyen) - mon- trant les Iocalitds A dinosaures du Cr6tac6 en Antarctique et proche-An- tarctique. Localitds du Cr6tac6 supdrieur : A, cours d'eau Mangahouanga, Nouvelle-Z61ande (?dryosaure) ; B, Ile de James Ross (ankyiosaure). Loca- lit6s du Cr6tac6 iinfddeur : C, Lightning Ridge, Nouvelies Galles du Sud, Australie (hypsilophodonts, ?iguanodontoide, th6ropodes, ?sauropode) ; D, rdgion du Cap d'Otway, Victoria, Australie (hypsilophodonts, thdropodes) ; E, r6gion du Cap de Paterson, Victoria, Auatralie (hypsilophodonts, thdro- podes). Des localit6s du Cr6tac6 sup&ieur et du Crdtac6 inf6rieur plus 61oign6es du cercle kntarctique sont connues en km6rique du Sud, mais ne sont pas indiqu6es ici.

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the Antarctic Circle. Together with the occurrence of small or- nithopods in New South Wales (Molnar & Galton 1986) and Victoria (Flannery & Rich 1981) Australia, this suggests that such forms inhabited the Antarctic continent itself. Because hypsilophodontians are not known from the northern conti- nents, we also suggest that further exploration of South Ameri- ca will result in their discovery.

The New Zealand climate during the terminal Cretaceous was cool to cold-temperate, with well-defined seasons (Stevens 1985). Clayton & Stevens (1965) report a mean water temp6ra- ture of 14.3 degrees C, similar to that of New Zealand offshore waters today. Bramwell & Whitfield (1974) present mean sea level air tempe;atures (based on the work of Fairbridge) of 14 degrees C which corroborate the water temperature of Clayton & Stevens. This suggests that small ornithopods were capable of surviving under such a cool-temperate climatic regime and an Antartic diurnal regime of prolonged summer daylight and winter night. This is a quite different environment, in the va- lues of these parameters, than those from which most dino-

saurs are known - however at least two other such faunae are known. These are the Lower Cretaceous of Victoria, Australia (Flannery & Rich 1981) and the Upper Cretaceous of Alaska (Davies 1987).

The morphological similarity of this specimen to correspon- ding material of Dryosaurus, with the disparity in times of their occurrence (the youngest dryosaurid, Valdosaurt~ nige- riensis last occurs in the Aptian : Galton & Taquet 1982), calls for some explanation of its survival here. Unfortunately we have none to offer : Vermeij (1987) has suggested that environ- ments at high latitudes offer "safe places" where taxa may sur- vive influences which elsewhere cause their extinction. This oc- currence may be an example of that effect, but until more is known of the Mangahouanga ornithopod we cannot rule out the possibility that the similarity of the ilium to those of dryo- saurids is the result of parallel evolution. The existence of other near-polar dinosaurian faunae presents opportunities for the testing of Vermeij's hypothesis in this context.

A c k n o w l e d g e m e n t s

Carter Holt Ltd kindly provided access to the locality. Drs. land Geological Survey helpfully assisted in the study of this P. M. Galton, P. Taquet and R. A. Thulborn and the New Zea- specimen. Mine D. Dubos provided the translation into French.

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Manuscrit d6posd le 14.03.1988 Manuscrit d6finitif re~u le 13.12.1988