The recent discovery of 245-million-year-old fossils belonging to one of the earliest dinosaur relatives could drastically alter our understanding of these giants lizards’ origins, as the species turned out to be much larger than researchers anticipated and walked on four legs.
Known as a Teleocrater, the creature in question was classified as an archosaur – a group which included birds, dinosaurs, pterosaurs, and crocodilians, according to the New York Times. While it was a cousin to the dinosaurs and not a direct ancestor, scientists nonetheless believed that it may shed new light on how these reptiles originally evolved during the Triassic period.
However, as the Chicago Tribune noted, a team of paleontologists working at a basin in southern Tanzania made a surprising discovery: they discovered Teleocrater rhadinus fossils that revealed that the species was not a small, bipedal reptile, but actually a seven-to-10-foot-long creature that walked on four legs and had a longer-than-expected tail and neck.
The discovery, which was reported Wednesday in the journal Nature, “goes to show that there’s a lot more out there that we just didn’t know, especially the early history of the larger group that dinosaurs belonged to: Archosauria,” lead author Sterling J. Nesbitt, a vertebrate paleontologist at Virginia Tech, told the Tribune. His team’s research could force scientists to reconsider what the first dinosaurs, and their ancestors, actually looked like, the newspaper noted.
Discovery could change our understanding of dinosaur evolution
As the Times explained, it was approximately 250 million years ago that the archosaurs split into two main branches: one that included birds and dinosaurs, and one which included crocodiles. In the case of the Teleocrater, it was an early member of the bird/dinosaur group and first appeared 10-15 million years before the appearance of the very first dinosaur.
Despite its link to the dinosaurs, Nesbitt’s team found that it bore little resemblance to dinosaurs as we know them. Not only did its size and long neck cause it to resemble a Komodo dragon, the creature has ankle bones that closely resembled those found in crocodiles. The discovery indicates that features previously believed to have developed only in one archosaur branch actually existed in a common ancestor of both groups, according to the Times.
“The ankle was really a big surprise with this animal, because all of the archosaurs on the bird side of the tree [including] dinosaurs all have what we call a bird-like ankle, which has a pretty simple hinge, and all the archosaurs on the croc side of the tree have what we call… a crocodile-like ankle,” Nesbitt told the Tribune. “That tells us that the crocodile ankle was primitive for the earliest archosaurs and that the bird ankle was derived from a crocodile-like ankle.”
The new study “changes our understanding of what that first step in the evolution of dinosaurs was like,” co-author Kenneth Angielczyk from the Field Museum in Chicago told the Tribune. “For the first time, we have a good idea of what the very first forms on the lineage leading to pterosaurs, dinosaurs, and birds looked like.” Randall B. Irmis, a paleontologist at the Natural History Museum of Utah who was not involved in the study, added that the findings would likely “spark a lot of research into how and why pterosaurs and dinosaurs evolved into such different forms from their early relatives.”
Image credit: Gabriel lio