Fossils attributed to a young man Tyrannosaurus rex They are another smaller species.
Madrid. A new analysis of fossils believed to be from a young man Tyrannosaurus rex shows that they were adults of a small tyrannosaur, with narrower jaws, longer legs and larger arms.
The species, Nanotyrannus lancensis, was first named decades ago, but was later reinterpreted as a young Tyrannosaurus rex.
The first skull Nanotyrant It was found in Montana in 1942, but for decades, paleontologists have gone back and forth on whether it was a separate species or simply a juvenile of the much larger Tyrannosaurus rex.
Nick Longrich, from the Milner Center for Evolution at the University of Bath, in England, and Evan Saitta, from the University of Chicago, in the United States, reanalyzed the fossils, looking at the growth rings, the anatomy of Nanotyrant and an earlier unrecognized fossil of a young Tyrannosaurus rex.
When measuring the bone growth rings of nanotyrant The researchers showed that they squeezed more toward the outside of the bone as growth slowed. It suggests these animals were almost full-sized, not fast-growing juveniles, the University of Bath reported.
Modeling the growth of the fossils showed that the animals would have reached a maximum of about 900 to 1,500 kilograms and 5 meters, about 15 percent the size of the fossil. Tyrannosaurus rex giant, which weighed up to 8 thousand kilograms and measured 9 meters or more.
The researchers published their findings in Fossil Studies.