New tyrannosaur bridges gap from medium to monstrous
Horse-sized dinosaur had brain, ears like its bigger relative T. rex
By Beth Geiger
A fossil from a new species of dinosaur is helping to bridge a crucial 20-million-year gap in tyrannosaur evolution.
The key fossil is a 90-million-year-old, grapefruit-sized partial skull from Uzbekistan’s Bissekty Formation. This tyrannosaur braincase, the first well-preserved one found from the mid-Cretaceous period, shows that, although still small, tyrannosaurs of the time already had brain and ear features of later tyrannosaurs. Researchers have dubbed the in-betweener Timurlengia euotica, meaning “well-eared.” They describe the new species in a paper to appear in the Proceedings of the National Academy of Sciences.