According to paleontology doctoral student Matt Baron from the University of Cambridge, the lead author of the study, the original dinosaur tree was designed more than a century ago and was based on hip shape. In that tree, the two major dinosaur groups are the Saurischia, a group with reptile-like hips that includes the brontosaurus, and the Ornithischia, a group with bird-like hips that includes the stegosaurus.
Theropods like the T. rex later evolved into modern birds, and this group was originally considered to be an offshoot of the Saurischia. The new report, published Wednesday in the journal Nature, now places them with the Ornithischia.
It also says dinosaurs are older than we thought, dating them to 247 million years ago, 10 million years further back in history than the standard theory. As dinosaurs roamed the Earth for 150 million years, Baron says, studying them is important to understanding how large animals change over time.
Baron and his team used computer simulation to create tens of of thousands of possible dinosaurs families, and focused on 450 characteristics of 75 species of dinosaur.
Paleontologist Kristi Curry Rogers from Minnesota’s Macalester College, who was not a part of the study, said, "If the authors are correct, this really turns our longstanding understanding of dinosaur evolution upside down!"
Excited about the study and its findings, Rogers said, "It means that animals that we've always thought were very closely related to each other might not be."
Dinosaur experts are divided on the subject, with the University of Chicago’s Paul Sereno calling the new family tree’s basis "weak."
"The central question the paper leaves unanswered for me is, 'Why?'" he said.
