A more subtle difference is the shape of the lacrimal bone, which made up the front part of the eye socket and was also part of the dinosaur’s skull ornamentation. In Tyrannosaurus rex, the top portion of the lacrimal has a concave shape, but in Tarbosaurus bataar the same portion of bone is domed.
“Tarbosaurus bataar is in a sense the Asian version of the Tyrannosaurus rex, they are close cousins,” said Lawrence Witmer, an anatomist and paleontologist at Ohio University.
Both had powerful jaws and teeth, big back legs and tiny arms, although Tarbosaurus had arms that were even smaller than those of T. rex, according to Philip Currie, a paleontologist at the University of Alberta.
The largest Tyrannosaurus found measured about 45 feet (14 meters) long, while the largest Tarbosaurus measured about 40 feet (12 meters) long, Currie told LiveScience in an email. “But there is always the possibility that bigger specimens will eventually be found for one or both.”
While clearly identifiable, tarbosaurs have only been found in a roughly 70-million-year-old rock formation in Mongolia, Tyrannosaurus rex remains have turned up in many fossil beds in North America. Both were apex predators, meaning they were at the top of the food chain, and, thanks to their lineage, both are considered tyrannosaurs.
This article originally appeared on livescience.com