Scientists have unearthed fossils of the earliest known dinosaur relative, a 245-million-years old giant reptile that walked on four legs like a crocodile. The six-foot-long, lizard-like carnivore, called Teleocrater rhadinus, was discovered in Tanzania. The finding fundamentally changes our ideas about the evolution of the prehistoric animals.
It is the earliest member of the bird-like side of the family. It is not a direct ancestor of dinosaurs, but it's the oldest known dinosaur cousin, researchers said. Teleocrater did not look much like a dinosaur. It resembled the monitor lizards alive today, researchers said.
It was between six and ten feet long, including its long neck and longer tail and it probably weighed between twenty and sixty-five pounds. It likely stood around two feet tall at the hip. Some of its features, like the jaw muscle attachments at the back of its skull, clearly put it in the bird-like archosaur camp with the dinos, it has a lot in common with its more distant crocodilian cousins, researchers said.
Its ankle joints could rotate from side to side as well as flexing up and down, while dinosaurs' and birds' ankle joints could only do a hinge-like up-and-down motion. That would have given Teleocrater a more splayed, crocodile-like gait rather than an ostrich-like trot.
"We used to think that many of the distinctive features of bird-line archosaurs evolved very quickly after they diverged from the crocodile line because early bird-line archosaurs like Marasuchus, Dromoeron, and Lagerpeton were small and very dinosaur-like," said Ken Angielczyk, associate curator at The Field Museum in the US.
"However, Teleocrater shows us that bird-line archosaurs initially inherited many crocodile-like features from the common ancestor of all archosaurs, and that the 'typical' bird-line features evolved in a step-wise fashion over a longer period of time," Angielczyk said.
Teleocrater is a missing link between dinosaurs and the common ancestor they share with crocodiles, he said.
"The discovery of such an important new species is a once-in-a-lifetime experience, said Sterling Nesbitt, an assistant professor at Virginia Polytechnic Institute and State University.
"The discovery of Teleocrater fundamentally changes our ideas about the earliest history of dinosaur relatives," said Nesbitt
