Fossils of 3-foot-tall T. rex relatives are evolutionary stepping stone

Pablo Tucker
May 9, 2019

The new name for the little dinosaur, Suskityrannus hazelae, is derived from the Zuni Native American tribe word "Suski", meaning coyote, from the Latin "tyrannus" meaning king and finally, "hazelae", for Hazel Wolfe, who funded numerous digs in the Zuni Basin.

Reconstruction of the tyrannosauroid Suskityrannus hazelae from the Late Cretaceous (about 92 million years ago).

Palaeontologists (scientists who study fossils) have discovered a new species of tiny T-Rex which shows its ancestors were a bit less terrifying.

The study's lead author, Sterling Nesbitt, a paleontologist at Virginia Tech in the United States, said that the fossils of the smaller T. rex cousin could provide one of the best examples yet as to how a smaller family of dinosaurs evolved into monstrous super predators.

The newly named tyrannosauroid dinosaur, Suskityrannus hazelae, stood around 3 feet tall at the hip and was about 9 feet long, the university said. "More broadly, tyrannosauroids go back to the Middle Jurassic, around 160 million years ago, but it is only at the end of the Cretaceous that they got big".

"Suskityrannus gives us a glimpse into the evolution of tyrannosaurs just before they take over the planet", said Nesbitt.

In fact, the first partial skull of the mini tyrannosaur was found in 1997 by Robert Denton, now a senior geologist with Terracon Consultants, an engineering consulting firm in New Jersey. "It also belongs to a dinosaurian fauna that just proceeds the iconic dinosaurian faunas in the latest Cretaceous that include some of the most famous dinosaurs, such as the Triceratops, predators like Tyrannosaurus rex, and duckbill dinosaurs like Edmotosaurus".

Paleontologists announced Monday in the scientific journal Nature Ecology & Evolution that the ferocious Tyrannosaurus rex (T. rex) evolved from dinosaurs no larger than a small child.

In describing the new find, Nesbitt said, "Suskityrannus has a much more slender skull and foot than its later and larger cousins, the Tyrannosaurus rex".

Sterling Nesbitt, an Assistant Professor of Geobiology at Virginia Tech, sits for a photo next to the fossilized bones of Suskityrannus hazelae, a miniature adult Tyrannosaurus dinosaur relative. It was bigger than earlier tyrannosauroids and had big feet needed for speed - something the T. rex lost.

At first, what they thought they had were the remains of something closer to a Velociraptor, Nesbitt explained, according to the release. "Clearly the most complete individual skeleton we had found in the entire basin and we had not even started to collect it".

"We did not know these fossils represented a tyrannosauroid for more than a decade after they were discovered", Nesbitt told Gizmodo in an email. The finding is important, he said, because it shrinks the time gap between the small, intermediate-grade tyrannosaurs and the big ones. Just three feet tall and nine feet long.

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