‘Teenage T. rex’ fossil is actually a different species

A fossil once assumed to be of a young Tyrannosaurus rex is in fact that of a fully grown adult of a different species altogether. The species, christened Nanotyrannus, is about half the length and one-tenth of the body mass of its larger cousin. The specimen also has distinct physical features such as longer arms and sharper, less curved teeth than T. rex. The classification of Nanotyrannus is a “mic drop”, says palaeontologist Steve Brusatte. “And that necessitates a fundamental reassessment of tyrannosaur classification and evolution.”