Reptile fossils hint at wide diversity of dinosaur ancestors

NEW YORK — Fossils of a fourlegged, meat-eating reptile are helping paint a more complicated picture of the ancestry of dinosaurs than scientists had understood.

The creature was not a direct ancestor, but was more like a cousin. It lived about 245 million years ago, roughly 10 million years before dinosaurs appeared.

It’s the oldest known member of an evolutionary branch of animals that eventually led to dinosaurs and pterosaurs, living relatively soon after that branch split away from the ancestry of crocodiles.

Researchers who found fossils in Tanzania in 2015 describe the creature in a paper released last week by the journal Nature. It’s called Teleocrater rhadinus (TEE’lee-oh-kray-tur rah-DEE’-nuhs).

It was two to three metres long, smaller than crocodiles.

While almost all early dinosaurs apparently walked on two legs, Teleocrater shows that a four-legged style was still present at this point, said Sterling Nesbitt of Virginia Tech in Blacksburg, lead author of the paper.

It also had a crocodile-like ankle, rather than the more bird-like ankle later seen in dinosaurs, and a surprisingly long neck, he said.

The paper’s analysis indicates such dinosaur relatives were more diverse than thought, he said.

Luis Chiappe of the Natural History Museum of Los Angeles County, who didn’t participate in the study, called the work important for understanding the origin of dinosaurs. “It tells you about a much more complex picture than what was previously imagined,” he wrote in an email.