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New evidence on deinonychosaurian dinosaurs from the Late Cretaceous of Patagonia

2005; Nature Portfolio; Volume: 433; Issue: 7028 Linguagem: Inglês

10.1038/nature03285

1476-4687

Fernando E. Novas, Diego Pol,

Amphibian and Reptile Biology

Deinonychosaurs, the theropod dinosaur group most closely related to birds, are known mostly from fossils from North America and Asia. A new example, from Patagonia, is the first to be found in the Southern Hemisphere, part of the Gondwana supercontinent in the Late Cretaceous. Its similarity to the northern forms suggests that there was less divergence between the southern and northern land masses than was thought. Most of what is known about the evolution of deinonychosaurs (that is, the group of theropods most closely related to birds) is based on discoveries from North America and Asia1. Except for Unenlagia comahuensis2,3 and some fragmentary remains from northern Africa4, no other evidence was available on deinonychosaurian diversity in Gondwana. Here we report a new, Late Cretaceous member of the clade, Neuquenraptor argentinus gen. et sp. nov., representing uncontroversial evidence of a deinonychosaurian theropod in the Southern Hemisphere. The new discovery demonstrates that Cretaceous theropod faunas from the southern continents shared greater similarity with those of the northern landmasses than previously thought. Available evidence suggests that deinonychosaurians were probably distributed worldwide at least by the beginning of the Cretaceous period. The phylogenetic position of the new deinonychosaur, as well as other Patagonian coelurosaurian theropods, is compatible with a vicariance model of diversification for some groups of Gondwanan and Laurasian dinosaurs.