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Tiny Throat Bone Confirms Nanotyrannus as a Separate, Mature Tyrannosaur

Throat-bone histology in a Science study shows the holotype was mature, introducing a validated aging tool that clarifies tyrannosaur diversity.

This illustration shows a Late Cretaceous face-off between an adult Nanotyrannus (left) and two juvenile T. rex, with a sub-adult T. rex watching from a distance. Jorge Gonzalez/Handout via REUTERS

Overview

  • Researchers counted growth rings in the hyoid of the Cleveland Museum holotype, indicating roughly 15–18 years old and fully or nearly grown.
  • The team validated hyoid microstructure as an age indicator by matching results in ostriches, alligators, caimans and dinosaur growth series at the Natural History Museum of Los Angeles County.
  • The finding follows an Oct. 30 study that used different bones and anatomical traits to independently conclude Nanotyrannus is distinct from Tyrannosaurus rex.
  • The confirmation reshapes views of Late Cretaceous ecosystems, with adult Nanotyrannus coexisting with T. rex and likely competing with juvenile tyrannosaurs.
  • Authors describe Nanotyrannus as a smaller, agile predator about 5 meters long and roughly 700 kilograms, contrasting with the stockier, stronger T. rex.