Overview
- A Nature study concludes the smaller 'Dueling Dinosaurs' predator was an adult Nanotyrannus, not a juvenile Tyrannosaurus rex.
- Bone growth-ring analysis and adult skeletal features indicate full maturity at death for the Montana specimen.
- Researchers document consistent differences from T. rex, including a higher tooth count, longer arms, fewer tail vertebrae and unique cranial nerve structures.
- The team recognizes two small tyrannosaurs in the record, distinguishing Nanotyrannus lancensis from a newly named species, Nanotyrannus lethaeus.
- The findings suggest multiple tyrannosaur species coexisted late in the Cretaceous and prompt a reassessment of fossils previously labeled as teenage T. rex, a view some specialists had favored.