Missing Middle? Fossils of Crocodile-like Ancestors to Dinosaurs Found

Imagine crocodiles with long necks and long legs running around? Yes, that’s how they were initially ruling out the theory of their miniature size before evolving into big size as previously thought. The missing middle has finally been resolved.

Researchers from National Science Foundation discovered the fossils of the new ancient species of Teleocrater rhadinus, in southern Tanzania that measured approximately 7-10 feet long, with long necks and tails. Rather than walking on two legs, they walked on four crocodilian-like legs, they said. The finding fills a major gap in fossil record, they say.

This is an artist’s rendering of T. rhadinus in its ancient habitat. CREDIT: Gabriel Lio

Judy Skog, a program director in the National Science Foundation’s (NSF) Division of Earth Sciences, said the finding “indicates that dinosaur origins should be re-examined now that we know more about the complex history and traits of these early ancestors.”

Teleocrater Rhadinus predated dinosaurs, living more than 245 million years ago during the Triassic Period. It survived right after a large group of reptiles known as archosaurs split into a bird branch and a crocodile branch. Hence, the Telecrator Rhadinus and its kin are the earliest known members of the bird branch of the archosaurs, they said.

“The discovery of such an important new species is a once-in-a-lifetime experience,” said Sterling Nesbitt, a paleobiologist at Virginia Tech and lead author of the paper published in the journal Nature.

The late paleontologist F. Rex Parrington first discovered T. rhadinus fossils in Tanzania in 1933 followed by the late Alan J. Charig, then-curator of fossil reptiles, amphibians and birds at the Natural History Museum of London, who was the first to study those original specimens in the 1950s. Charig could not determine whether the creature was more closely related to crocodilians or to dinosaurs, as they lacked ankles and other bones.

The new species T. rhadinus hunting an early close relative of mammals.CREDIT:  Gabriel Lio

The new specimens, found in 2015, fill the missing middle with the intact ankle bones and other parts of the skeleton which helped scientists now to determine that the species is one of the oldest members of the archosaur tree and had a crocodilian look.

“It’s so exciting to solve puzzles like Teleocrater, where we can finally tease apart tricky mixed assemblages of fossils and shed light on broader anatomical and biogeographic trends in an iconic group of animals,” said Michelle Stocker, a paleobiologist at Virginia Tech and co-author of the paper.

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