SAO PAULO, Nov. 10 (UPI) -- For the first time, paleontologists have uncovered dinosaur and lagerpetid fossils side by side, proof early dinosaurs coexisted with their evolutionary precursors.
The fossils were found in Brazil's Santa Maria Formation and comprise two new species. Scientists named the new dinosaur species Buriolestes schultzi and the lagerpetid Ixalerpeton polesinensis.
The rock in which the fossils were found is estimated to be 230 million years old; it and its fossilized inhabitants hail from the beginning of the Late Triassic.
The discovery offers new insights into the nature of the first branches of the dinosaur family tree. The findings -- detailed in the journal Current Biology -- also suggest the diversification of dinosaurs, and their rise to ecological dominance, was a relatively slow process.
Scientists have previously suggested the closest relatives of the dinosaurs were quick to disappear. The new evidence proves otherwise.
"We now know for sure that dinosaurs and dinosaur precursors lived alongside one another and that the rise of dinosaurs was more gradual, not a fast overtaking of other animals of the time," study author Max Langer, a researcher at the University of Sao Paolo, said in a news release.
The recovered fossils, representing four specimens, were very well preserved. Their discovery offers scientists a new and detailed understanding of the anatomical features common among the earliest dinosaurs.
These features can be studied to glean information about the behavior of early dinosaur species. For example, the fossil teeth of the Buriolestes schultzi specimens suggest the species fed on a variety of small animals, but not plants.
Though Buriolestes schultzi looks like a therapod, scientists believe the species is one of the earliest members of the suborder Sauropodomorpha, a lineage that yielded the long-necked dinosaurs known was sauropods.
Researchers hope the latest discovery is a harbinger of more well-preserved examples of early Triassic life.