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 meat-eating 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 Matthew Baron, a paleontology doctoral student at the University of Cambridge in England. He is the lead author of the study in
Wednesday’s journal Nature.
“If the authors are correct, this really turns our long-standing understanding of dinosaur evolution upside down,” Kristi Curry Rogers, a paleontologist at Macalester College in Minnesota who wasn’t part of the study, wrote in an email.
Dinosaurs are split into two groups. One group has birdlike hips and is called Ornithischia (pronounced or-ni-THISS-kee-a). It includes the spiky-tailed stegosaurus. The group with reptilelike hips is called Saurischia (saw-RIS-kee-a), and includes the long-necked brontosaurus. (Please view the pictures)
T. rex and other theropods, which 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.
“It means that animals that we’ve always thought were very closely related to each other might not be,” said Rogers, who praised the study, saying it prompts a whole bunch of new questions.
Baron and his colleagues looked at 450 characteristics of 75 dinosaur species. They used computer simulations to group together those with similar characteristics, creating tens of thousands of potential dinosaur family trees. The proposed family tree combines the 80 most likely scenarios, he said.
The grouping is important because it helps explain how big animals changed with time, Baron said, noting that the dinosaurs ruled Earth for more than 150 million years.
His research suggests that dinosaurs popped up 247 million years ago — 10 million years earlier than the standard theory says — with a plant-eating dinosaur from Tanzania in East Africa. It’s called Nyasasaurus and was six to 10 feet tall.
He also found a reptilian ancestor that’s not quite a dinosaur, but as close as you can get. Surprisingly, it was in Scotland. Previous theories pointed to dinosaurs first evolving out of the Southern Hemisphere. Many outside scientists said there wasn’t enough evidence to support Baron’s northern concept.
The paper is already dividing dinosaur experts.
Famed University of Chicago paleontologist Paul Sereno called the basis of the Baron family tree “weak” and said “the central question the paper leaves unanswered for me is Why?”
Matthew Carrano, dinosaur curator at the Smithsonian’s National Museum of Natural History, said it’s hard to side with any theory because early dinosaur fossil records are so incomplete.
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