Nanotyrannus Was Never What We Thought – Fossil Analysis Reveals Its True Identity

Nano is among the most famous dinosaurs – we all know that. But were Megalodon, Mosasaurus or Pteranodon dinosaurs too? If you can't answer that, check out how our merch can help: https://wildsparks-shop.fourthwall.com/en-usd Makes a great gift, too! ____________________________ In this video: Nanotyrannus was a real, separate dinosaur species, and it lived alongside Tyrannosaurus rex in North America. Two independent research teams confirmed this in 2025, ending a debate that started in 1942. That year, an unknown fossil collector working Montana's Hell Creek Formation found a small tyrannosaur skull. In 1946, researchers filed it under Gorgosaurus, a different tyrannosaur group. Nobody realized it was something new. In 1988, paleontologist Robert Bakker reexamined the skull. Its bones had fused, a sign of a fully grown animal. He named it Nanotyrannus and gave the species its own name for the first time. But... In 1999, paleontologist Thomas Carr argued the opposite. He said Nanotyrannus was just a juvenile Tyrannosaurus rex, not its own species. His theory spread through textbooks and documentaries for decades. The debate finally got settled through bone histology, the study of growth rings inside fossilized bone. Growth rings space out during active growth and pack tightly once an animal stops growing for good. This tight pattern is called an external fundamental system. In 2025, a team led by Lindsay Zanno at the North Carolina Museum of Natural Sciences studied a Nano specimen nicknamed the Dueling Dinosaurs, unearthed in Montana in 2006. A leg bone showed the tight growth rings of a fully mature animal, around twenty years old at death. The skull showed an extra sinus cavity, a differently shaped jaw bone, a higher tooth count than any known Tyrannosaurus rex, and a missing subnarial foramen. These features are embryonic traits, fixed from birth, and they cannot be explained by growth alone. So it was more proof for Nano as its own species. A second team studied a different fossil entirely: the hyoid bone, a small throat bone that anchors the tongue. It reached the exact same conclusion. Nanotyrannus was a mature, distinct species. One specimen, nicknamed Jane, doesn't match this pattern and has been classified as a second species, Nanotyrannus lethaeus. If you thought the debate was over here, you're mistaken. Paleontologist Stephen Brusatte has raised an unresolved question: If small tyrannosaur skeletons belong to Nanotyrannus, where are the juvenile Tyrannosaurus rex? This video breaks down the full story: how a single misidentified skull from 1942 led to one of paleontology's longest-running debates, and how two labs (hopefully) finally settled it in 2025. #wildsparks #nanotyrannus #dinosaur #dinosaurdocumentary