Dinosaur origin: the evidence of the footprint record

MARSICANO, CLAUDIA; DOMNANOVICH, NADIA; MANCUSO, ADRIANA

Rio de Janeiro

Conferencia; II Congreso Latinoamericano de Paleontologia de Vertebrados; 2005

The Triassic represents a crucial time in the evolutionary history of dinosaurs: it records the origin and subsequently ascendancy of the group at the end of the period. The Late Triassic dinosaur body-fossil record is rather scarce but it shows an already widespread distribution of the group with representatives of both ornithischians and saurischians. Particularly, well-preserved skeletons are primary known from southern South America, where basal ornithischians (Pisanosaurus), theropods (Herrerasaurus, Eoraptor) and sauropodomorphs (Saturnalia, Guaibasaurus) were exhumed from lower Late Triassic levels (Carnian) of Argentina and Brazil. However and according to the present understanding of dinosaur phylogeny, all this evidence strongly suggests that basal cladogenesis of dinosaurs was well under way before the end of the Triassic although, the body-fossil record has failed to document this early diversification to date.