A new tyrannosaur fossil has been discovered in Utah — and it’s tiny compared to its more famous relative T. rex.
Meet Moros intrepidus, a small tyrannosaur that lived in Utah’s Emery County during the Cretaceous period. At 96 million years old, it is the oldest Cretaceous tyrannosaur species yet discovered in North America. The find narrowed a 70-million-year gap in the tyrant dinosaur record.
And by small, think the size of a mule deer. Moros was only 3 or 4 feet tall at the hip. The specimen found was estimated at being more than seven years old and nearly full grown. It’s name means “harbinger of doom.”
While medium-sized primitive tyrannosaurs have been found in North America dating from the Jurassic period, (around 150 million years ago), the iconic Tyrannosaurus rex showed up in the Cretaceous period (around 81 million years ago). Lindsay Zanno, paleontologist at North Carolina State University and lead author of a paper describing the research, explained that before the discovery of Moros, paleontologists didn’t know how the tyrant dinosaur got from a relatively small hunter to the large apex predator we’re familiar with — the fossil record was a blank slate.
“When and how quickly tyrannosaurs went from wallflower to prom king has been vexing paleontologists for a long time,” said Zanno in a news release. “The only way to attack this problem was to get out there and find more data on these rare animals.”
Zanno and her team spent a decade hunting for dinosaur bones within rocks from the Late Cretaceous period. Their search finally produced teeth and a hind limb from Moros. Zanno described Moros as being lightweight and exceptionally fast.
"These adaptations, together with advanced sensory capabilities, are the mark of a formidable predator,” Zanno said. “It could easily have run down prey, while avoiding confrontation with the top predators of the day.”
The discovery of Moros leads paleontologists to believe T. rex took advantage of the warming temperatures and rising sea levels at the end of the Cretaceous period.
Zanno said, “We now know it took them less than 15 million years to rise to power.”