A new species of the primitive dinosaurThecodontosaurus(Saurischia: Sauropodomorpha) and its implications for the systematics of early dinosaurs

Adam M. Yates
2003 Journal of Systematic Palaeontology  
SYNOPSIS Juvenile sauropodomorph specimens from a Late Triassic/Early Jurassic fissure fill in Pant-y-ffynnon Quarry, South Wales are redescribed and named as a new species, Thecodontosaurus caducus. T. caducus can be diagnosed by the presence of pleurocoel-like pits on the neurocentral sutures of the sixth, seventh and eighth cervical vertebrae. It is further distinguished from the type species of the genus, T. antiquus, by the primitive shape of its proximal humerus and ilium. Data from this
more » ... um. Data from this specimen are incorporated into a cladistic analysis of basal sauropodomorph relationships. It is found that Thecodontosaurus is basal to all other sauropodomorphs, with the exception of Saturnalia from the late Carnian of Brazil. As such Thecodontosaurus is a key taxon, with a novel combination of characters that has important implications for early dinosaur phylogenetics. Thecodontosaurus provides evidence that 'prosauropods' are paraphyletic with respect to Sauropoda and that Herrerasauridae lies outside the clade containing Sauropodomorpha + Theropoda.
doi:10.1017/s1477201903001007 fatcat:m7jz77myxzdqxk7k6eg5eksu5m