Classification: Reptilia, Saurischia
Body length: 5 m
Body weight: 450 kg
Period: Late Cretaceous
Location: North America
Nanotyrannusis possibly a juvenile specimen of Tyrannosaurus. Nanotyrannus is the smallest known tyrannosaurid and was one of the last tyrannosaurids to live before the Cretaceous Extinction. Many paleontologists consider the skull to belong to a juvenile Tyrannosaurusrex. However, there are minor differences between the two species, including the higher number of teeth and the presence of fused bones in the holotype.These features have lead some paleontologists to recommend keeping the two genera separate until further research or discoveries clarify the situation.