An unusually large and unusually old carnivorous dinosaur roamed what is now New Mexico in the United States 74 million years ago.
This is what British and American researchers reveal in a new study published in the journal Scientific Reports. And it's not just any dinosaur, but perhaps an ancestor of the most famous of them all - Tyrannosaurus rex.
"It is thought to be part of the evolutionary line of dinosaurs that is the direct ancestor of T. rex," says Johan Lindgren, a lecturer at Lund University, who was not involved in the study.
Unexpectedly large
The find in question is a tibia that was excavated in the Hunter Wash area. The bone is about 80 percent of the size of the largest T. rex specimen found so far.
It is full-sized compared with a T. rex leg, but smaller than the largest known T. rex, says Lindgren.
The researchers believe that the dinosaur in question weighed up to five tons, making it up to twice the size of other tyrannosaurids that lived at the time, several million years before the T. rex emerged.
No matter how you look at it, the find suggests that there was something the size of a T. rex roaming around here in what is now New Mexico 74 million years ago.
Great diversity
Not only was the Hunter Wash dinosaur big, it could also provide clues to a question that has long been debated among paleontologists - namely, where the T. rex actually originated. Some argue that it migrated from Asia to North America - others believe it originated in southern North America. This find lends support to the latter theory.
Late last year, scientists were able to establish that another dinosaur, the small Nanotyrannus, was its own species and not just a teenage T. rex. The fact that a number of tyrannosaur species existed at the same time is perhaps no stranger than the fact that felines like lions, cheetahs, and leopards live in the same time and place today.
This shows that there was a high diversity and species richness - everything from quite small to very large tyrannosaurids in what is today North America, says Johan Lindgren.
