By Will DunhamWASHINGTON, Dec 4 (Reuters) – Paleontologists for decades debated whether meat-eating dinosaur Nanotyrannus was actually just a juvenile Tyrannosaurus. But within a span of five weeks, the matter seems to have been definitively resolved by two new studies showing that Nanotyrannus was clearly distinct from T. rex.The latest study, published on Thursday, focused on a throat bone called the hyoid from the first Nanotyrannus fossil ever discovered, a skull unearthed in Montana in 1942. Researchers detected a record of growth in the hyoid – akin to a tree’s annual growth rings – showing that this individual was around 15-18 years old, so either fully grown or nearly so.AdvertisementAdvertisementAdvertisementAdvertisementThis finding follows a study published on October 30 by different researchers that used other bones to establish a growth record and identified anatomical differences in fossils of Nanotyrannus and Tyrannosaurus, also contradicting the notion they were the same dinosaur.The hyoid was part of a skull fossil that was the “holotype” specimen of Nanotyrannus, stored at the Cleveland Museum of Natural History.”The key finding is that the holotype specimen of Nanotyrannus lancensis, the fossil that formally defines the species, represents a mature individual, and therefore cannot belong to an immature Tyrannosaurus rex, as had often been interpreted in the past. Instead, it shows that Nanotyrannus is a distinct species of carnivorous dinosaur that lived alongside T. rex,” said Princeton University paleontologist Christopher Griffin, lead au …
