Paleontology

Nanotyrannus was not a teenaged T. rex

New fossil evidence suggests Nanotyrannus was a separate lineage that lived alongside T. rex

An illustration shows four T. rex looking dinos attacking a fifth in a jungly setting. The fallen dino is a juvenile T. rex and the four are a different diminutive species of tyrannosaur.

A pack of Nanotyrannus attacks a similarly sized juvenile T. rex in this artist’s depiction of dinosaur diversity in what’s now Hell Creek, Mont., in the Late Cretaceous Period.

Anthony Hutchings

By Carolyn Gramling

For decades, researchers have debated whether a fossil of a small, fierce theropod belonged to a teenaged Tyrannosaurus rex or was a separate species.