New Tyrannosaur Species Debuts at the Smithsonian

New dinosaur fills in 20-million-year gap in tyrannosaur evolution.

"Clues from the life of Timurlengia allow us to fill in gaps and better understand the life and evolution of other related dinosaurs, like T. rex," Sues said in the release.

Sues, along with other paleontologists including Steve Brusatte of the University of Edinburgh, studied the fossils and reconstructed the brain of Timurlengia using CT scans of the brain case.

Studies of the fossils show that the species grew rapidly toward the end of their 70 million-year existence: from 600-pound, horse-sized hunters to fearsome giant beasts weighing up to 7 tons.

According to the release, "The ancestors of T. rex would have looked a whole lot like Timurlengia, a horse-sized hunter with a big brain and keen hearing that would put us to shame," Brusatte said. "Only after the ancestral tyrannosaurs evolved their clever brains and sharp senses did they grow into the colossal sizes of T. rex."

The results of the study are published in the Proceedings of the National Academy of Sciences.