Nanotyrannus was one of a number of tyrannosaurid bones that were discovered among the same rock formations where Tyrannosaurus rex bones were uncovered. Originally many of these remains were classified as different dinosaurs, though eventually many of them would be assigned to T. rex as juveniles.
Nanotyrannus was originally thought to be an exception, since paleontologists believed that its skull bones were fused together, meaning it was an adult and not a juvenile. This would mean that it was a much smaller dinosaur than T. rex, though it was similar in appearance. However, a later analysis revealed that it was in fact a young specimen, leading most scientists to reclassify it as a juvenile Tyrannosaurus rex.
A fossil known as “Dueling Dinosaurs”, which depicted two dinosaurs locked in combat, was discovered in 2006 by ranchers in Montana. This well-preserved fossil contained two injured dinosaurs – one was Triceratops, a horned plant eater, while the other was a member of the tyrannosaur family.
The Dueling Dinosaurs fossil went through a long legal battle over who actually owned the specimens, until 2020, when the fossils were purchased by the North Carolina Museum of Natural Sciences. While it was believed that the Dueling Dinosaurs could shed more light on whether Nanotyrannus was a valid genus, paleontologists concluded that the dinosaur battling the Triceratops was a juvenile T. rex.
