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This Little T. Rex Relative Discovered in the U.S. Was Smaller Than a Human

Had this discovery arrived a quarter century earlier, maybe it would have made for a nice velociraptor replacement in Jurassic Park. A new study has detailed an early relative of the T. Rex that stood just over a meter high at its hip...

new tyrannosaur dinosaur
Jorge Gonzalez

Had this discovery arrived a quarter century earlier, maybe it would have made for a nice velociraptor replacement in Jurassic Park. A new study has detailed an early relative of the T. Rex that stood just over a meter high at its hip. 

The new species, Moros intrepidus, was discovered in Emery County, Utah and lived around 96 million years ago. While it's not likely to keep children up at night, it helps fill in a crucial gap in the fossil record that could explain how tyrannosaurs went from small carnivores that ducked other apex predators to the T. Rex, one of the most fearsome creatures to ever stomp around the planet.

There is still mystery surrounding how tyrannosaurs transitioned to the massive creatures they're more commonly recognized as. That's largely because of a gap between tyrannosaurs of the Jurassic period (about 150 million years ago) and the iconic late Cretaceous hunters that gave Jeff Goldblum the injuries that resulted in that sultry statue.

"When and how quickly tyrannosaurs went from wallflower to prom king has been vexing paleontologists for a long time," said Lindsay Zanno, head of paleontology at the North Carolina Museum of Sciences and lead author of a paper describing the research in Communications Biology. "The only way to attack this problem was to get out there and find more data on these rare animals.

"Early in their evolution, tyrannosaurs hunted in the shadows of archaic lineages such as allosaurs that were already established at the top of the food chain," she said.

The lower leg bones of the species were discovered in the same area where Zanno's team previously uncovered Siats meekerorum, an allosaur that lived around the same time as Moros. The researchers say Moros was about the size of a mule deer and believe this specimen to have been about six-to-seven years old and nearly fully grown. That means tyrannosaurs moved from Moros to T. Rex in over the course of 15-16 million years. 

"Although the earliest Cretaceous tyrannosaurs were small," Zanno said, "their predatory specializations meant that they were primed to take advantage of new opportunities when warming temperatures, rising sea-level, and shrinking ranges restructured ecosystem at the beginning of the Late Cretaceous... We now know it took them less than 15 million years to rise to power."

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Dustin Nelson is a Senior Writer on the news team at Thrillist. Follow him @dlukenelson.