Scientists identify new, smaller 'cousin' of 9-ton T. rex

Scientists on Monday have identified a new relative of the T. rex, an animal that was only “marginally longer than the just the skull” of its fully grown larger cousin, according to Virginia Tech.  

The newly named tyrannosauroid dinosaur, Suskityrannus hazelae, stood around 3 feet tall at the hip and was about 9 feet long, the university said. If it stretched its duck-billed head, an adult human maybe “would be looking at it in the eye,” said Sterling Nesbitt, a paleontologist at Virginia Tech, who discovered the dinosaur. 

Nesbitt found a set of its bones in 1998 when he was just 16 as a high school student. He was serving as a volunteer on a dig in New Mexico with a famed paleontologist. 

“My discovery of a partial skeleton of Suskityrannus put me onto a scientific journey that has framed my career,” said Nesbitt, the lead author of the study in the journal “Nature Ecology and Evolution.”

But for about two decades, scientists weren’t certain what it was, until other small cousins of T. rex were discovered. 

“The small group of tyrannosauroid ( dinosaurs would give rise to some of the biggest predators that we’ve ever seen,” Nesbitt said.  

While the typical weight for a full-grown T. rex was roughly 9 tons, the Suskityrannus hazelae is believed to have weighed between 45 and 90 pounds, according to the university. 

“Suskityrannus has a much more slender skull and foot than its later and larger cousins, the Tyrannosaurus rex,” Nesbitt told the university. “The find also links the older and smaller tyrannosauroids from North America and China with the much larger tyrannosaurids that lasted until the final extinction of non-avian dinosaurs.”

The new dinosaur is named after the Zuni Native American tribe word, “Suski” for coyote. Nesbitt told the university that permission was granted from the Zuni Tribal Council to use the word “Suski.” 

Suskityrannus hazelae dates back 92 million years, which is about 20 million years before the T. rex roamed Earth. The fossil also dates back to the Cretaceous Period, when some of the largest dinosaurs ever discovered lived, the university said. 

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

T. rex's new cousin isn’t the first or even smallest of the Tyrannosaurus family tree, but Nesbitt said it provides the best example of how this family of modest-sized dinosaurs evolved into the towering horror of movies, television shows and nightmares.

Smithsonian Institution paleobiologist Hans Sues, who wasn’t part of the study, said it was an important find. “Suskityrannus is the first really good record of the early tyrannosaurs in North America,” he wrote in an email.

It is unclear why these carnivores, which weren’t particularly big compared with other dinosaurs alive at that time, later evolved to be so enormous.

Nesbitt said the newly discovered species is probably among the last of the little guys. It was bigger than earlier tyrannosauroids and had big feet needed for speed — something the T. rex lost.

The Associated Press contributed to this report.