A new study conducted by University of Edinburgh researchers suggests that the ferocious Tyrannosaurus rex was an invasive species, contrary to the popular belief that it was a native to North America. The findings point to the origins of the species as Asia, which eventually dispersed into North America when the opportunity arose.
"It's possible that T.rex was an immigrant species from Asia," said study co-researcher Steve Brusatte, who participated in the research, although he admits that the findings aren't a "slam dunk" and that more research is needed to further solidify the findings.
Little is known about the family tree of one of the biggest meat eaters to ever live on land. In order to shed light on its past, the team analyzed 28 different tyrannosaur species and created a family tree in order to pinpoint when and where each species lived.
Although fossil evidence is still lacking, using their tree as a guide, the team believes that the evidence thus far points to tyrannosaur predecessors having lived on the supercontinent Pangaea, which eventually began to break apart approximately 200 million years ago during the Triassic period. This hypothesis explains why tyrannosaur fossils have been found in various locations around the world, from Asia to North America and Europe.
Over time, tyrannosaurs evolved in their respective locations, explaining why those in Asia looked physically different from the ones in North America. However, the team believes that when the seaway between Asia and North America disappeared 67 million years ago, a land bridge connected the two continents and the T. rex likely crossed this route into North America.
Analysis of the T. rex's skeletal features revealed characteristics that point to Asian origins, and supporting this idea is the fact that they are closely related to two Asian tyrannosaurs, Tarbosaurus and Zhuchengtyrannus.
"Tarbosaurus is the Asian version of T. rex," Brusatte said. "Or, you could say that T. rex is the North American version of Tarbosaurus. They are so similar in terms of their monstrous size, their proportions, their massive jaw muscles and thick teeth and even many minutiae of their skull bones."
The findings were published in the Feb. 2 issue of the journal Scientific Reports.
