Tyrannosaurus Rex and his buddies could be on the move as a new study proposes a massive shake-up of the dinosaur family tree.

Scientists who took a deeper look at dinosaur fossils suggest a different evolutionary history for dinosaurs, moving theropods such as T-Rex to a new branch of the family tree and hinting at an earlier and more northern origin for dinosaurs.

The revised dinosaur tree makes more sense than the old one, initially designed more than a century ago based on hip shape, said Matt Baron, a paleontology doctoral student at the University of Cambridge in England. He is the lead author of the study in the journal Nature.

"If the authors are correct, this really turns our longstanding understanding of dinosaur evolution upside down," Kristi Curry Rogers, a paleontologist at Macalaster College in Minnesota who wasn't part of the study, wrote in an email.

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Dinosaurs are split into two groups. One group has bird-like hips and is called Ornithischia. It includes the stegosaurus. The group with reptile-like hips is called Saurischia, and includes the brontosaurus.

Theropods, which include T-Rex and the type of dinosaurs that later evolved into modern-day birds, were considered an offshoot from the group that includes the brontosaurus. The new study moves them to the group that includes the stegosaurus, but on a different branch.

He also found an animal that's not quite a dinosaur, but as close as you can get, that is a reptilian ancestor. And it was in Scotland.

Previous theories pointed to dinosaurs first evolving out of the Southern Hemisphere.

The paper is already dividing dinosaur experts. AP