Nouveau nom pour Thecodontosaurus caducus

Discussion:

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Posté par Dinomaster il y a 17 ans

A new genus name is proposed for Thecodontosaurus caducus Yates, 2003, the 'Thecodontosaurus' from South Wales.

Galton, P.M., Yates, A.M. & Kermack, D. (2007) Pantydraco n. gen. for Thecodontosaurus caducus Yates, 2003, a basal sauropodomorph dinosaur from the Upper Triassic or Lower Jurassic of South Wales, UK. Neues Jahrbuch für GEologie und Paläontologie, abh., 243: 119-125

Abstract: Numerous isolated bones from a Rhaetian (Upper Triassic) fissure fill in Clifton, Bristol, England have been referred to the basal sauropodomorph Thecodontosaurus Riley & Stutchbury 1836 (type genus of T. antiquus Reley & Stutchbury vide OWen, 1842). T cadacus Yates 2003 (Rhaetian of Lower Triassic fissure fill, South Wales) is based on several articulated partial skeletons of juvenile individuals. T. antiquus is based on isolated neotype dentary that does not possess an autopomorphy or a unique combination of characters. This dentary is unusually short and deep but this character is also present in T. caducus and Saturnalia tupiniquim (Upper Triassic, Brazil). However, the characters of refered Clifton postcrania cannot be used to diagnose Thecodontosaurus because there are three humeral mprphs from Clifton. No other bones from Clifton have characters diagnostic for T. cadacus and the ages of the two fissure fills may be different. The gracile mprph long refered to T. antiquus is present in the monospecific assembalge of 1000's of isolated sauropodomorph bones from the Rhaetian fissure fill at Tytherington Quarry near Bristol. A comprehensive cladistic analysis of basal sauropodomorphs, in which T. antiquus (characters mostly based on Tyterington bones) and T. caducus were included as sepparate terminal taxa, failed to recover a monophyletic Thecodontosaurus in all of the most parsimonious trees. T. caducus Yates, 2003 is made the type species of Pantydraco n. gen., which can be diagnotised by the autapomorphic presence of pneumatic openings on cervical vertebrae 6-8. The prominent apex of the anteroposteriorly low assymetrical deltopectoral crest is at 40% of humeral length (versus low at 25%, and high at 40% and at 50% in Clifton humeri) and the tubercle medial to the head is small (large in Clifton humeri).

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