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

SMITH, NATHAN; MAKOVICKY, PETER; AGNOLIN, FEDERICO; EZCURRA, MARTIN D.; PAIS, DIEGO; SALISBURY, STEVEN

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

ROYAL SOC

Lugar: Londres; Año: 2008 p. 2085 - 2093

0962-8452

The fossil record of Australian dinosaurs in general, and theropods in particular, is extremely sparse. Herewe describe an ulna from the Early Cretaceous Eumeralla Formation of Australia that shares uniqueautapomorphies with the South American theropod Megaraptor. We also present evidence for thespinosauroid affinities of Megaraptor. This ulna represents the first Australian non-avian theropod withunquestionable affinities to taxa from other Gondwanan landmasses, suggesting faunal interchangebetween eastern and western Gondwana during the Mid-Cretaceous. This evidence counters claims ofLaurasian affinities for Early Cretaceous Australian dinosaur faunas, and for the existence of a geographicalor climatic barrier isolating Australia from the other Gondwanan continents during this time. The temporaland geographical distribution of Megaraptor and the Eumeralla ulna is also inconsistent with traditionalpalaeogeographic models for the fragmentation of Gondwana, but compatible with several alternativemodels positing connections between South America and Antarctica in the Mid-Cretaceous