Large Cretaceous sphenodontian from Patagonia provides insight into lepidosaur evolution in Gondwana

SEBASTIÁN APESTEGUÍA; FERNANDO E. NOVAS

NATURE

Nature Publishing Co.

Lugar: Londres; Año: 2003 p. 609 - 612

0028-0836

Sphenodontian reptiles successfully radiated during Triassic and Jurassic times, being driven almost to extinction during the Cretaceous. The sparse Early Cretaceous record of sphenodontians has been interpreted as reflecting the decline of the group in favour of lizards, their suspected ecological successors. However, recent discoveries in Late Cretaceous beds of Patagonia partially modify this interpretation. Numerous skeletons of a new sphenodontian, Priosphenodon avelasi gen. et sp. nov., were collected from a single locality in the Cenomanian-Turonian Candeleros Formation, where it is more abundant than any other tetrapod group recorded in the quarry (e.g., Crocodyliforms, Serpentes, Dinosauria, and Mammalia). Adult specimens of Priosphenodon reached one meter in length, being larger than any previously known terrestrial sphenodontian. Available evidence suggests that sphenodontians were not a minor component of the Cretaceous terrestrial ecosystems of South America, and that their ecological replacement by squamates was delayed until the early Tertiary. The new discovery helps to bridge the considerable gap in the fossil record (around 120my) separating the Early Cretaceous sphenodontians from their living relatives (Sphenodon).