New archosaur species shows that precursor of dinosaurs and pterosaurs was armored

"We are just starting to understand that there were many dinosaur-like creatures across the planet well before dinosaurs evolved," said the study's lead author Sterling Nesbitt, associate professor of geosciences at Virginia Tech and a research associate in the American Museum of Natural History's Division of Paleontology. "Dinosaurs were latecomers to the Triassic reptile party. They showed up well after many dinosaur-looking reptiles were established across our planet."

Archosaurs are reptiles that are divided into two major branches: the bird-line, which includes pterosaurs and dinosaurs, including living dinosaurs (birds); and the crocodilian line, including crocodiles, alligators, caimans, and gharials. The newly described species, named Mambachiton fiandohana, is the earliest diverging member of the bird line of archosaur evolution.

The fossil, which is about 235 million years old, was found in 1997 in Madagascar by a team of researchers led by the Museum's Frick Curator of Fossil Mammals John Flynn, who worked at the Field Museum at the time, in close collaboration with scientists and students at the University of Antananarivo in Madagascar.

"This discovery documents the importance of the southern hemisphere fossil record in understanding this important period of the Triassic, when dinosaurs were first appearing," Flynn said. "This time interval is really poorly known elsewhere in the world, showing the tremendous value of our quarter-century-long Madagascar-U.S. research and education partnership to advancing scientific knowledge."

This photo shows the fossilized cervical vertebra and overlaying osteoderms of the new archosaur species Mambachiton fiandohana. Credit: Sterling, et. al

Reconstruction of Mambachiton fiandohana. Scale bar = 25 cm. Credit: Nesbitt, et al.

The fossilized cervical vertebra and overlaying osteoderms of the new archosaur species Mambachiton fiandohana shown in a photograph (top), line drawing (middle), and computed tomography (CT) rendering model with the osteoderms and matrix removed (bottom). Scale bar = 5 cm. Credit: Nesbitt et al.