With its bone-crushing teeth and monstrous proportions, there’s no creature more fearsome in the public imagination than the mighty Tyrannosaurus rex. Sixty-five million years after it went extinct, though, T. Rex is having an identity crisis: in recent months, much of what we know about this iconic monster has been “flipped on its ear,” says Stephen Brusatte, a vertebrate paleontologist at the American Museum of Natural History in New York. Indeed, the tyrannosaur’s size, speed and eating habits have all been thrown into question, leaving dino lovers wondering if the T. Rex really was so fearsome after all.

The North American T. Rex and its Asian cousin, the Tarbosaurus, are two of about 10 dinosaurs that fall into the tyrannosaur family, Brusatte says. Because tyrannosaurs were at the top of the prehistoric food chain, paleontologists long believed different members of this family couldn’t coexist. But a newly described fossil has challenged that assumption. With its thin teeth, horns, and hollow bones, Alioramus altai was a “ballerina” compared to T. Rex, says Brusatte, lead author of the study. Unearthed in Mongolia’s Gobi Desert, Alioramus lived side by side with the Asian Tarbosaurus, suggesting not all tyrannosaurs were “top chiefdom brutes,” he notes. Perhaps because Alioramus wasn’t viewed as competition, Tarbosaurus didn’t seem to mind this smaller, daintier relative. Continue…