Tyrannosaurus rex is arguably the most famous of all the dinosaur species, with starring roles in pretty much every
The new species was discovered when the team took a closer look at a museum specimen of a 71-73 million-year-old partial skull. The skull was discovered in the Hall Lake Formation, New Mexico, USA in the 1980s and is currently on display at the
“[The] skull/jaw was originally described and assigned to T. rex in 1986,”
Close analysis of the skull revealed that not only was it not a
“New Mexicans have always known our state is special, now we know that New Mexico has been a special place for tens of millions of years,” Dr Anthony Fiorillo, Executive Director of NMMNHS, said in a statement seen by IFLScience.
Given that T. rex is so famous, this helped the team identify key subtitle differences between the bones within the skull of a T. rex and the skull of the new species.
“The differences are subtle, but that’s typically the case in closely related species. Evolution slowly causes mutations to build up over millions of years, causing species to look subtly different over time,” said Dr Nick Longrich, a co-author from the Milner Centre for Evolution at the University of Bath, UK.
Dr Lucas told IFLScience that the longer and shallower jaws in the new species suggest that it “likely had less bite force than in a T. rex.” Regardless it was still an impressively large dinosaur, roughly the same size as a T. rex, which measured up to 12 meters (40 feet) from head to tail and 3.6 meters (12 feet) tall. Given the dates of the fossil, it shows that tyrannosaurs grew to a giant size near the end of the Campanian (toward the end of the
Phylogenetic analysis also suggests that the species could be a sister species to the T. rex making it the closest known relative. According to Dr Lucas, it could even be a “plausible ancestor”, though the paper notes not a direct one. The discovery suggests that Tyrannosaurs may have evolved south of an island continent called Laramidia that existed between 100 and 66 million years ago. This island was extremely large and would have stretched from what is now Alaska to Mexico. Towards the end of the Cretaceous period, the team posits, Tyrannosaurus started spreading north, alongside other giant species like
The paper is published in