Spinosauroidea, Late Jurassic




Yüklə 105.59 Kb.
səhifə1/5
tarix23.04.2016
ölçüsü105.59 Kb.
  1   2   3   4   5


KEY WORDS

Dinosauria,

Theropoda,

Spinosauroidea,

Late Jurassic,

France,


Europe.
Redescription of Streptospondylus altdorfensis, Cuvier’s theropod dinosaur,

from the Jurassic of Normandy

Ronan ALLAIN

Laboratoire de paléontologie, Muséum national d’Histoire naturelle,

UMR 8569 du CNRS,

8 rue Buffon, F-75005 Paris (France)



rallain@mnhn.fr

Allain R. 2001 - Redescription of Streptospondylus altdorfensis, Cuvier’s theropod

dinosaur, from the Jurassic of Normandy, Geodiversitas 23(3) : 349-367


ABSTRACT


Redescription of Streptospondylus altdorfensis, Cuvier’s theropod dinosaur, from the Jurassic of Normandy

The theropod dinosaur remains from the Callovo-Oxfordian of the Vaches Noires, figured for the first time by Cuvier are redecrisbed. The systematic revision shows that Streptospondylus altdorfensis is the valid name to which the whole of the material should be assigned. A few vertebral features suggest the close relationships existing between Streptospondylus and Eustreptospondylus from the Callovian of England : both genera are related to the Spinosauroidea. The diversity of the European theropods at the end the Middle Jurassic and the beginning of the Late Jurassic is outlined.





INTRODUCTION
The main part of the bones described in this paper belongs to a private collection initially constituted by the Abbé Bachelet in the 1770 (Cuvier 1800a). The material, collected in the region of Honfleur, comprised cranial and postcranial material of two teleosaurs, as well as some theropod postcranial remains. It was then given to the Museum under Comte Beugnot’s requisition by C. Guersent who was at the time professor at the Museum in Rouen (Cuvier 1800a). This collection was then attached by Cuvier (1812) to some material found in the region of Le Havre and described in 1776 by the Abbé Dicquemare. The exact origin of the Bachelet Collection remains however dubious. Cuvier (1824 : 143) mentions, without precising their exact origin, that these bones have been collected « near Honfleur » and that « it is only by the labels attached to these bones that I have been able to know their geographic origin, as well as the name of their collector, and his idea that they were sperm whale bones .» On the same aspect, the exhaustive content of the Bachelet collection has never been published, neither by its finder nor by Cuvier. The vertebrae described herein were in fact figured by Cuvier along with the remains of the “Gavial de Honfleur” (1824 : pl.VIII ;IX), whereas the distal end of the pubis, the tibia, the astragalus and the calcaneum were associated with remains from Buckland’s Megalosaurus (1824 : pl. XXI), without it being indicated if this second batch originally belonged to the Bachelet collection. Cuvier (1824), nevertheless precising that all these pieces come form Honfleur’s surroundings, suggests that they have a common origin. An examination of the collection catalogue of the Muséum national d’Histoire naturelle, Paris, tells us as well that the pubis, the tibia, the astragalus and the calcaneum have been found at the Vaches Noires. It’s probably on the basis of these data that Piveteau (1923 : 121) grouped the whole of the material and precised its origin. The anatomic relations between the vertebrae, the identical aspect of the fossilisation of the various bones and the clod partially covering these bones all go the same way. Except for the distal end of the femur, acquired long after by the Museum, the whole material described thereafter is then considered coming from the shale of the Vaches Noires cliffs, dated Upper Callovian-Lower Oxfordian. These theropod remains were the first to be described from diagnostic remains. It’s also the first theropod being given a binomial name although it is antedated by the genus name Megalosaurus Buckland, 1824.
Abréviations

MNHN Muséum national d’Histoire naturelle, Paris;



OUMJ Oxford University Museum, Oxford.


SYSTEMATICS



In the second edition of Ossements Fossiles (1824), Cuvier refers some material found in the region of Honfleur to two species of gavials that he distinguishes one from the other by the length of the snout (« Long snouted head », Short snouted head »).Cuvier comforts this distinction by accentuating the differences existing between the two vertebral systems found « in association » with the skulls. Each of these systems is thus referred to one or the other of the skulls : the « proximal convex system » to the long snouted species, the « concave system » to the short snouted one. Meanwhile, Geoffroy Saint-Hilaire (1825) unites both species under the genus name Steneosaurus. He distinguishes the long snouted species, S. rostromajor, whose type specimen (MNHN 8900) is the skull figured by Cuvier (1824 : pl.8, figs 1 ; 2), from the short snouted species, S. rostrominor, whose type (MNHN 8902 ; Cuvier 1824 : pl. X, figs 1-4) is represented by a complete mandible. The study and description by Geoffroy Saint-Hilaire are solely based on the cranial anatomy of the two crocodiles. The two binomial names thus created apply only to the skulls and in no way to the vertebrae already described by Cuvier and which Geoffroy Saint-Hilaire doesn’t include in his work. Von Meyer (1832) separates the two crocodiles at the genus level. He creates the names Metriorhynchus geoffroyii for the short snouted species and Streptospondylus altdorfensis for the long snouted one, but differing in this way from Geoffroy Saint-Hilaire, includes all the material already described by Cuvier. Meyer perpetuates Cuvier’s mistake by assigning the vertebrae and the skull to the same taxon. Although the name Streptospondylus that he proposes, as he outlines it himself (Meyer 1832: 227), makes reference to the peculiar structure of the vertebrae, he doesn’t define any type specimen within the material referred to the species. Streptospondylus altdorfensis Meyer, 1832 is then an animal composed of theropod vertebral remains as well as teleosaur remains including the skull used by Geoffroy Saint-Hilaire as the type species of Steneosaurus rostromajor. This same skull is in fact composed of the remains of two distinct teleosaurs species (Eudes-Deslongchamps 1870: 303), Steneosaurus edwardsi Deslongchamps, 1866 and Metriorhynchus superciliosum Blainville, 1853 (Steel 1973). Following the ICZN (1999 : art. 73.1.5), a part of the material having been excluded from the composite type and transferred to other taxa, Streptospondylus altdorfensis is de facto only characterised by postcranial material, and the theropod vertebrae are designed here as a lectotype of this taxon. The specific name chosen by von Meyer is a reference to the cranial remains of teleosaurs found in Altdorf (Walch 1776 ; Collini 1784) and which, following Meyer’s opinion, belong to the same taxon as those found near Honfleur. Bronn (1837 : 517) notes that the specific name altdorfensis is inappropriate for the Norman material, as he denotes a distribution not applicable to Cuvier’s material. This condition is however not enough to invalidate the specific name. Streptospondylus altdorfensis is thus the good name to which the vertebrae originally described by Cuvier are to be referred.

This conclusion, also reached by Wells (unpublished), hasn’t imposed itself to all. Most of the works following von Meyer’s don’t recognise the validity of the specific name and bring forth confusion. In 1842, Owen creates a new species, Streptospondylus cuvieri, and compares it with the Honfleur vertebrae which he names Streptospondylus rostromajor. The type of S. cuvieri is the anterior half of a dorsal vertebra coming from the Lower Bathonian of Chipping Norton. This isolated vertebra and whose description by Owen holds no scientific value, has never been figured and is nowadays lost : S. cuvieri is then considered nomen dubium. In 1861, Owen still associates the skulls and the vertebrae from Honfleur and places them, within crocodiles, in the suborder Opisthocoelia. More confusion is added when he includes in this suborder composite material (theropod, crocodile, sauropod) coming from various English localities and that he puts in its whole to the genus Cetiosaurus Owen, 1842. This arrangement doesn’t prevent him to recognise the validity of the genus Streptospondylus ; but, without any explanation, Owen now designate the material under the specific name cuvieri and no more rostromajor. From then, several authors (Lennier 1870 ; Phillips 1871 ; Nopsca 1906, Huene 1926 ; Piveteau 1923) take the material kept in Paris for the type species Streptospondylus cuvieri. These works are unfounded because nothing proves that the Honfleur material can be referred to S. cuvieri which is based on a lost fragment of vertebra with no specific value. However, if such were the case, Streptospondylus cuvieri would be a junior synonym of S. altdorfensis and become invalidated.

More recently, Walker (1964), after having shown that the type of Streptospondylus cuvieri wasn’t Honfleur material and after having placed Streptospondylus altdorfensis in synonymy with Steneosaurus rostromajor, referred Cuvier’s theropod material to a new species, Eustreptospondylus divesensis and chose for type of this new species the skull described by Piveteau in 1923. By doing so, he made closer the material from Normandy and the almost complete skeleton of Eustreptospondylus oxionensis, Walker, 1964 type species of the genus, although it does exist, as we shall see, differences between the two type materials. It has since then been demonstrated (Taquet & Welles 1977) that the postcrania described by Piveteau and the skeleton kept at the Oxford University Museum belonged to two distinct genera, Piveteausaurus Taquet & Welles, 1977 and Eustreptospndylus Walker, 1964. Moreover, nothing indicates that the Honfleur vertebrae are co-specific with the postcrania of Piveteausaurus divesensis. Walker’s conclusions (1964) are only acceptable if one considers Streptospondylus altdorfensis a junior synonym of Steneosaurus rostromajor. But, in contradiction to what Walker (1964) assumes, the bibliographic list is not the same for the two species. Steneosaurus rostromajor, differing in that point with Streptospondylus altdorfensis, is only based on the skull figured by Cuvier (1822 : pl. X, figs 1-4) as specified by Geoffroy Saint-Hilaire (1825 : 147). It has been shown here above that this skull could be excluded from the type material and referred to another taxon. That’s what Geoffroy Saint-Hilaire (1825) has done and that Walker (1964) doesn’t take into account. The conclusions of the latter are thus rejected.
Superorder DINOSAURIA Owen, 1842

Order THEROPODA Marsh, 1881

Suborder TETANURAE Gauthier, 1986

Superfamily SPINOSAUROIDEA Stromer, 1915

Genus Streptospondylus Meyer, 1832
Streptospondylus altdorfensis Meyer, 1832
Streptospondylus altdorfensis Meyer, 1832, 106, 226.

Streptospondylus rostromajor sensu Owen, 1842, partim [non Geoffroy Saint-Hilaire]: 88.

Streptospondylus cuvieri Owen, 1842 – Owen 1859 : 23.

Laelaps gallicus Cope, 1867 : 235.

Megalosaurus cuvieri (Owen, 1842) – Huene 1908 : 332, figs 312, 313.

Eustreptospondylus divesensis Walker, 1964, partim : 124.
CHRESONYMY

Crocodile fossile Cuvier 1800b : 159

Espèce inconnue de crocodile Cuvier 1808 : 95, pls 1, 2.

Espèce inconnue de crocodile Cuvier 1812 : 16, pls 1, figs 3, 6, 10, pl. 2, figs 12, 13.



Espèce gigantesque de saurien Cuvier 1824 : 343, pl. 21, figs 34-39.

Streptospondylus cuvieri Owen, 1842 – Lennier 1870 : 42, pl. 8, fig. 1. – Phillips 1871 : 321, fig. 124. – Zittel 1890 : 724, fig. 627. – Nopsca 1905 : 289. – Piveteau 1923 : 121, pl. 1, fig. 4, pl. 3, figs. 1-3, pl. 4, figs 1-5. – Lapparent & Lavocat 1955 : 934.

Megalosaurus cuvieri (Owen, 1842) – Huene 1932 : 222. – Swinton 1955 : 132.

Eustreptospondylus divesensis Walker, 1964 – Welles & Long 1974 : 205.
Lectotype - Last cervical vertebra and two first dorsals (MNHN 8787) ; last dorsal vertebra and two first sacrals (MNHN 8794) ; last sacral vertebra and first caudal (MNHN 8788) ; series of three dorsal vertebrae (MNHN 8907) ; dorsal vertebra (MNHN 8789) ; anterior dorsal vertebra (pectoral) (MNHN 8789) ; anterior dorsal vertebra (pectoral) (MNHN 8793) ; distal end of left pubis (MNHN 8605); distal end of right fibula (MNHN 8606) ; distal end of right tibia (MNHN 8607) ; right astragalus (MNHN 8606) ; right calcaneum (MNHN 8609).
Referred material – Distal end of left femur (MNHN 9645).
Horizon – Shales from Upper Callovian or Lower Oxfordian of the Vaches Noires cliffs, Calvados, France.

Diagnostic – Middle size theropod. Two hypapophyses on anterior dorsal vertebrae ; centrum of anterior dorsal vertebrae strongly opisthocoelous and ventrally flattened, posterior dorsal vertebrae platycoelous ; centrum of median and posterior dorsal vertebrae elongated ; lateral extension of the medial buttress above the dorsomedial edge of the ascending process of the astragalus doesn’t reach the median part of the distal end of the tibia. ; large depression at the base of the ascending process of the astragalus, lack of posteromedial process on the astragalus.
Description
  1   2   3   4   5


Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©azrefs.org 2016
rəhbərliyinə müraciət

    Ana səhifə