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

An Erratum to this article was published on 30 June 2005


Sphenodontian reptiles successfully radiated during Triassic and Jurassic times, but were driven almost to extinction during the Cretaceous period1. The sparse Early Cretaceous record of sphenodontians has been interpreted as reflecting the decline of the group in favour of lizards, their suspected ecological successors2. However, recent discoveries in Late Cretaceous beds in 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 (for example, Crocodyliformes, Serpentes, Dinosauria and Mammalia)3,4. Adult specimens of Priosphenodon reached one metre in length, larger than any previously known terrestrial sphenodontian. Here we propose, using available evidence, 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 120 million years) that separates the Early Cretaceous sphenodontians5,6,7 from their living relatives (Sphenodon).

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Figure 1: Priosphenodon avelasi.
Figure 2: Cladogram depicting phylogenetic relationships of Priosphenodon avelasi within Sphenodontia.


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We thank the Avelás, Salinas and Pincheira families, C. Muñoz, L. Fernández and the ENDEMAS for their valuable help in the field. S. Reuil, A. Scanferla, M. Isasi and E. Villalba are also acknowledged for preparation of specimens; J. González and G. Lío for illustrations; and H. Canuti for photographs. Field work and study were supported by The National Geographic Society, the Agencia Nacional de Promoción Científica y Tecnológica, Akapol SA, and the Renault Argentina (to F.E.N.), and by The Jurassic Foundation and The Rotary Club (to S.A.). S. Evans, R. Molnar, G. Rougier and D. Pol substantially improved this work with useful comments and critical review.

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Correspondence to Fernando E. Novas.

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This file includes details of the cladistic analysis and character list for the study. (DOC 46 kb)


This file contains details of an error in the posting of the Supplementary Information online. (DOC 19 kb)

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Apesteguía, S., Novas, F. Large Cretaceous sphenodontian from Patagonia provides insight into lepidosaur evolution in Gondwana. Nature 425, 609–612 (2003).

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