Credit: Unsplash/CC0 Public Domain
Phys.org has an article about Nanotyrannus lancensis. A paper in the journal Fossil Studies proposes that N. lancensis is a distinct species of tyrannosaur and not a juvenile T. rex.
The first skull of Nanotyrannus 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 T. rex.
Dr. Nick Longrich, from the Milner Centre for Evolution at the University of Bath, and Dr. Evan Saitta, from the University of Chicago, have re-analyzed the fossils, looking at growth rings, the anatomy of Nanotyrannus, and a previously unrecognized fossil of a young T. rex.
Measuring the growth rings in Nanotyrannus bones, the researchers showed that they became more closely packed towards the outside of the bone as growth was slowing. It suggests these animals were nearly full size; not fast-growing juveniles.
