Nanotyrannus was not a teenage T. rex.

The article discusses the recent resolution of a long-standing debate in paleontology regarding the classification of a small theropod dinosaur, previously thought to be a juvenile Tyrannosaurus rex, which is now identified as a distinct species called Nanotyrannus lancensis. Researchers have analyzed a well-preserved skeleton from Montana's Hell Creek Formation, revealing it to be the first adult specimen of Nanotyrannus, demonstrating significant anatomical differences from T. rex, including variations in limb and tail bone structure. The findings suggest that Nanotyrannus and T. rex coexisted and occupied different ecological niches, indicating a greater diversity of dinosaur species at the end of the Cretaceous Period. The research prompts a reevaluation of previous studies on T. rex, as it may have been conflated with characteristics of Nanotyrannus. [Extracted from the article]