A Megaraptor-like theropod (Dinosauria: Tetanurae) in Australia; support for faunal exchange across eastern and western Gondwana in the mid-Cretaceous

SMITH, N. D.; MAKOVICKY, P. J.; AGNOLIN, F. L.; EZCURRA, M. D.; PARIS, D. F.; SALISBURY, S. W.

PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. SERIES B: BIOLOGICAL SCIENCES.

Royal Society Publishing

Lugar: Londres; Año: 2008 vol. 275

0962-8452

The fossil record of Australian dinosaurs in general, and theropods in particular, isextremely sparse. Here we describe an ulna from the Early Cretaceous EumerallaFormation of Australia that shares unique autapomorphies with the South Americantheropod Megaraptor. We also present evidence for the spinosauroid affinities ofMegaraptor. This ulna represents the first Australian non-avian theropod withunquestionable affinities to taxa from other Gondwanan landmasses, suggesting faunalinterchange between eastern and western Gondwana during the mid-Cretaceous. Thisevidence counters claims of Laurasian affinities for Early Cretaceous Australian dinosaurfaunas, and for the existence of a geographic or climatic barrier isolating Australia fromthe other Gondwanan continents during this time. The temporal and geographicdistribution of Megaraptor and the Eumeralla ulna is also inconsistent with traditionalpalaeogeographic models for the fragmentation of Gondwana, but compatible with several alternative models positing connections between South America and Antarctica inthe mid-Cretaceous.