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R E V U E D E R E V u E D E ISSN VOL. 26, N° 2, 2007 Museum d'Histoire Naturelle . Ville de Gen eve . Suisse Revue de Paléobiologie, Genève (décembre 2007) 26 (2) : 505-591 ISSN 0253-6730 Notes on the remains of archosaurian reptiles, mostly basal sauropodomorph dinosaurs, from the 1834 fissure fill (Rhaetian, Upper Triassic) at Clifton in Bristol, southwest England Peter M. GALTON1 Abstract Many of the best preserved teeth and bones of archosaurian reptiles found in 1834 in an Upper Triassic Rhaetian fissure fill on Durdham Down in Clifton (now in Bristol), southwest England were destroyed in 1940. Based on an 1875 map, the site is positively identified as within Quarry Steps Quarry. This paper includes an annotated catalogue, copies of most of the illustrations from 1840 to 1908, and photos of important extant specimens. Most of the recognizable, mostly unassociated and incomplete bones have long been referred to the basal sauropodomorph dinosaur Thecodontosaurus RILEY & STUTCHBURY, 1836 (as T. antiquus MORRIS, 1843), with gracile and robust morphs of several of the appendicular bones as a sexual dimorphism. The deltopectoral crest of unassociated Clifton humeri is plesiomorphic for basal sauropodomorphs, being anteroposteriorly high and markedly asymmetrical in lateral view with a short edge distal to the very prominent apex. The apex is at 40% (measured perpendicular to long axis of humerus) of total length in gracile ones and +50% in robust ones of the same size. However, the former position is plesiomorphic for sauropodomorphs, the latter derived, and no other basal sauropodomorph species has such a marked dimorphism. The only partial skeleton from Clifton, which includes a forelimb and girdle, has a third humeral morph with a low symmetrical deltopectoral crest with a rounded apex at 25% of length. Whatever the status of the gracile and robust morphs, the characters of referred postcranial bones from Clifton cannot be used to distinguish the species of Thecodontosaurus RILEY & STUTCHBURY, 1836 that, along with T. antiquus RILEY & STUTCHBURY vide OWEN, 1842, may be a nomen dubium. However, T. antiquus is retained for the slender humeral morph pending the description of referred material from a Rhaetian fissure fill at Tytherington Quarry, Avon. In the humerus ofPantydraco (Thecodontosaurus) caducus (Upper Triassic/Lower Jurassic, Wales) the apex of the asymmetrical deltopectoral crest is at 40% of the length and the process is low, a morph that is not represented at Clifton. The Clifton forelimb and girdle is made the holotype of Asylosaurus yalensis n. gen. et sp. The manus shows lateral reduction, so phalangeal formula is 2-3-4-2-?1, and the humerus has a large medial tubercle (small in Welsh humerus). The other Clifton bones are identified as either : A. very basal Sauropodomorpha indet (could be Asylosaurus or Thecodontosaurus, includes slender morph bones) ; B. Anchisauria indet (more derived than A, includes robust morph bones) ; or C. basal Sauropodomorpha indet (could be A or B). An ilium and two femora are very basal Theropoda (or possibly Dinosauriformes) ; other theropod remains include a small tooth crown with fine perpendicular denticles, a metacarpal I, a slender recurved manual ungual, and an astragalus. A dorsal centrum may be from an ornithischian dinosaur. Rileyasuchus KUHN, 1961 (type species Palaeosaurus platyodon RILEY & STUTCHBURY, 1840), a nomen dubium, is a heterodont crurotarsal phytosaur now represented by two teeth and two humeri. The denticles are angled slightly apically on the expanded mesial blade and perpendicular to the distal edge. Palaeosauriscus KUHN, 1959 (type species Palaeosaurus cylindrodon RILEY & STUTCHBURY, 1840) is based on lost teeth ; it is Archosauria indet but may be a valid taxon based on the subcircular cross-section and fine, obliquely inclined denticles. A few bones are none of the above and are Archosauria indet (dentary with teeth, scapula-coracoid) and even Reptilia indet (?prootic, parietal, distal femur, tibia, metapodial). Key words Sauropodomorpha, Anchisauria, Theropoda, Phytosauria, Asylosaurus, Palaeosauriscus, Rileyasuchus, Thecodontosaurus, Upper Triassic, England, Anatomy, Taxonomy. Résumé Notes sur les restes de reptiles archosaures, pour la plupart des dinosaures sauropodomorphes basaux, du remplissage, en 1834, de la fissure du Trias supérieur (Rhétien, Trias supérieur), à Clifton (Bristol), sud-est de l’Angleterre.- Nombre de dents et d’os fossiles les mieux préservés de reptiles archosaures trouvés en 1834 dans le remplissage d’une fissure du Trias supérieur (Rhétien) de Durdham Down à Clifton (de nos jours à Bristol), dans le sud-ouest de l’Angleterre, ont été détruits en 1940. D’après une carte de 1875 le site est clairement identifié comme se trouvant dans la carrière de Quarry Steps. Ce travail inclut un catalogue commenté, des reproductions de la plupart des illustrations de 1840 à 1908, et des photos des spécimens restants les plus importants. La plupart des os que l’on peut reconnaître, incomplets et en grande partie non associés, ont longtemps été attribués au dinosaure sauropodomorphe basal Thecodontosaurus RILEY & STUTCHBURY, 1836 (comme T. antiquus MORRIS, 1843), avec des morphes gracile et robuste de plusieurs os appendiculaires interprétés comme du dimorphisme sexuel. La crête deltopectorale des humérus non associés de Clifton, 1. Professor Emeritus, University of Bridgeport, Bridgeport, CT USA ; Curatorial Affiliate, Peabody Museum of Natural History, Yale University, New Haven, CT USA. 315 Southern Hills Drive, Rio Vista CA 94571-2153 USA ; E-mail : [email protected], [email protected] 506 P. M. GALTON qui est haute antéro-postérieurement et très asymétrique en vue latérale avec un bord distal court par rapport à l’apex proéminent, est plésiomorphe pour les sauropodomorphes basaux. L’apex est situé à 40% de la longueur totale (mesuré perpendiculairement à l’axe longitudinal de l’humérus) chez les formes graciles et à +50% chez les formes robustes de la même taille. Cependant, la première position est considérée comme plésiomorphe et la seconde comme dérivée pour les sauropodomorphes, et aucune autre espèce de sauropodomorphe basal ne présente un dimorphisme aussi marqué. Le seul squelette partiel de Clifton, qui comprend un membre antérieur et une ceinture, montre un troisième morphe huméral avec une crête deltopectorale symétrique basse portant un apex arrondi situé à un quart de la longueur. Quel que soit le statut des morphes gracile et robuste, les caractères des os postcrâniens rapportés de Clifton ne peuvent être utilisés pour distinguer l’espèce de Thecodontosaurus RILEY & STUTCHBURY, 1836 qui, avec T. antiquus RILEY & STUTCHBURY vide OWEN, 1842, pourrait être un nomen dubium. Néanmoins, T. antiquus est retenue pour le morphe huméral gracile en attendant la description du matériel rapporté provenant d’un remplissage de fissure du Rhétien de Tytherington Quarry, Avon. Chez l’humérus de Pantydraco (Thecodontosaurus) caducus (Trias supérieur/Jurassique inférieur, Pays de Galles), l’apex de la crête deltopectorale asymétrique est situé à 40% de la longueur et le processus est bas, correspondant à un morphe non représenté à Clifton. Le membre antérieur et la ceinture de Clifton deviennent l’holotype de Asylosaurus yalensis n. gen. et sp. La main montre une réduction latérale, de sorte que la formule phalangienne est 2-3-4-2-?1, et l’humérus possède un grand tubercule médial (petit chez l’humérus gallois). Les autres ossements de Clifton sont identifiés comme appartenant à : A, un Sauropodomorpha très basal indéterminé (qui pourrait être Asylosaurus ou Thecodontosaurus, incluant des os du morphe gracile) ; B, un Anchisauria indéterminé (plus dérivé que A, incluant des os du morphe robuste) ; ou C, un Sauropodomorpha basal indéterminé (qui pourrait être A ou B). Un ilium et deux fémurs appartiennent à un Theropoda très basal (ou à un possible Dinosauriformes). D’autres restes incluent une petite couronne dentaire à fins denticules perpendiculaires, un métacarpien I, une phalange distale de la main mince et incurvée, et un astragale. Un centrum dorsal pourrait appartenir à un dinosaure ornithischien. Rileyasuchus KUHN, 1961 (espèce type Palaeosaurus platyodon RILEY & STUTCHBURY, 1840), un nomen dubium, est un phytosaure crurotarsal hétérodonte maintenant représenté par deux dents et deux humérus. Les denticules forment un angle léger apicalement sur la lame distal élargie et perpendiculaire au bord distal. Palaeosauriscus KUHN, 1959 (espèce type Palaeosaurus cylindrodon RILEY & STUTCHBURY, 1840) est basé sur des dents perdues ; il s’agit d’un Archosauria indéterminé qui pourrait être un taxon valide d’après la section transversale subcirculaire et de fins denticules inclinés obliquement. Un petit nombre d’ossements n’appartient pas aux taxons mentionnés plus haut et pourrait être rapporté à des Archosauria indéterminés (dentaire avec des dents, scapula-coracoïde), voire même à des Reptilia indéterminés (?prootique, pariétal, partie distale d’un fémur, tibia, métapode). Mots-clés Sauropodomorpha, Anchisauria, Theropoda, Phytosauria, Asylosaurus, Palaeosaurisus, Rileyasuchus, Thecodontosaurus, Trias supérieur, Angleterre, Anatomie, Taxonomie. Contents I. Introduction ...........................................................................................................................................................507 II. Museum abbreviations ...........................................................................................................................................513
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