Overview
- Researchers describe NCSM 40000, a rare near-complete specimen with skull, limbs and tail that enabled direct, comprehensive comparison with Tyrannosaurus rex.
- Histological analysis indicates the animal was about 20 years old and fully grown, yet only roughly a tenth the mass of an adult T. rex.
- The specimen differs from T. rex in key traits, including more teeth, larger forelimbs, and only 35 tail vertebrae versus 40–45 in T. rex.
- The study identifies at least two species within the genus—Nanotyrannus lancensis and Nanotyrannus lethaeus—and reassigns several long-debated fossils.
- The famous 'dueling dinosaurs' fossil long labeled as T. rex versus Triceratops is reinterpreted as featuring Nanotyrannus, revising predator diversity and life‑history models for the late Cretaceous.