Dinosaur Demoted to 'Ancient Reptile' Status

A four-legged weed-whacker of sorts that lived some 230 million years ago just lost its dinosaur affiliation.

While past analyses of this once-dinosaur called Azendohsaurus madagaskarensis were based on its teeth and jaws, the new study relied on the entire skull of the extinct animal discovered in the late 1990s in southwestern Madagascar.

The result suggests A. madagaskarensis is a member of a very early branch on the reptile evolutionary tree.

"Even though this extraordinary ancient reptile looks similar to some plant-eating dinosaurs in some features of the skull and dentition, it is in fact only distantly related to dinosaurs," said John J. Flynn, curator in the Division of Paleontology at the American Museum of Natural History in New York. "With more complete material, we re-assessed features like the down-turned jaw and leaf-shaped teeth found in A. madagaskarensis as convergent with some herbivorous dinosaurs."

Convergent evolution refers to the process in which similar adaptations evolve independently in different groups of organisms.

More than a decade ago, scientists published work in the journal Science suggesting this animal was an early dinosaur based on analyses of fossils of teeth and jaws found in 1972 near a village in Morocco's Atlas Mountains.

The animal was, and still is, considered an archosauromorph, as dinosaurs are a subset of that group. ...

via Dinosaur Demoted to 'Ancient Reptile' Status | LiveScience.