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Nanotyrannus
Nanotyrannus
Nanotyrannus is a genus of tyrannosauroid dinosaur that lived in what is now western North America during the Late Cretaceous.
History and changes
In 2025, Lindsay Zanno and James Napoli published a revision identifying the Dueling Dinosaurs specimen nicknamed Bloody Mary or Manteo as a skeletally mature Nanotyrannus lancensis. They also described a second species, Nanotyrannus lethaeus, based on the Jane specimen and its differences from N. lancensis.
In 1988, Robert T. Bakker, Michael Williams and Phil Currie redescribed the original skull and named the genus Nanotyrannus. Their initial research interpreted its fused skull bones as evidence that the animal was an adult.
Charles W. Gilmore described the skull CMNH 7541 as Gorgosaurus lancensis in 1946. David Hosbrook Dunkle had collected the skull in 1942; its locality was subsequently corrected to the Hell Creek Formation rather than the Lance Formation.
Scope and limitations
Compared with Tyrannosaurus, Nanotyrannus had a slender, low skull with small crests or horns immediately in front of the eyes. Its forelimbs were both absolutely and proportionally larger than those of its relatives.
Its fossils are mainly known from the Hell Creek Formation. Nanotyrannus lived about 67 to 66 million years ago, during the Maastrichtian age, and survived until the Cretaceous–Paleogene extinction event.
Background and related concepts
Christopher T. Griffin and colleagues argued in 2025 that microscopic study of the hyoid bone showed the original N. lancensis skull belonged to a mature individual. D. Cary Woodruff and colleagues questioned their methodology for studying hyoid bone tissue in 2026.
The classification dispute concerned whether the skull represented a separate dinosaur or an immature Tyrannosaurus rex. Thomas Carr's 1999 analysis interpreted it as immature, leading Carr and many other paleontologists to consider it a juvenile T. rex.
References
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