Nanotyrannus

Nanotyrannus (meaning "dwarf tyrant") is an extinct genus of tyrannosauroid dinosaur. It was one of the last non-avian (not bird) dinosaurs to ever lives in Late Cretaceous, in Maastrichtian stage, between 67 to 66 milion years ago. It has long been argued that Nanotyrannus is nothing more than a juvenile of Tyrannosaurus rex or a similar genus.Currie P.J; Hurum, J.H; Sabath K. 2003. Skull structure and evolution in tyrannosaurid dinosaurs. Acta Palaeontologica Polonica. 48 (2): 227–234. The problem is that the very few skeletons found are all only fragmental. Most people believe it is a new genus of dinosaur and not just a juvenile Tyranosaurs. The type species, N. lancensis, was originally named as species of Gorgosaurus in 1946, but, reclassified as distinct and new taxon. A new study of 2025 suggered that Nanotyrannus is a valid genus, and is not a related genera, and yes, a basal tyrannosaur of the distinct sole family Nanotyrannidae.    

A second species, N. lethaeus, It was proposed as a distinct species from the "Jane" (BMRP 2002.4.1) holotype specimen, which was previously believed to be part of the N. lancensis specimens. The differences include a thinner skull and more robust body, as well as notable differences in the vertebrae of the spine and tail. Size of N. lacensis is based in the proposed adult specimen "Bloody Mary" fossil, and is estimates in 5.5 meters (18 ft) long and 850 kg. N. lethaeus is large than N. lancensis, based in holotype, he It would reach between 5.4 and 6 meters (18 to 19.7 feet) in length, with a similar weight, reaching 856 kg.

 Taxonomy 
The first alleged specimen was found in Montana in 1942. It was thought to have been a Gorgosaurus, but it was reclassified in 1988. It was a bit smaller than a Gorgosaurus. Research has found that the Tyrannosaurids have grown to be robust and giant. Nanotyrannus has a similar body shape to a young Tyrannosaur.Gilmore, C.W. (1946). "A new carnivorous dinosaur from the Lance Formation of Montana". Smithsonian Miscellaneous Collections. 106: 1–19.Zanno, Lindsay E.; Napoli, James G. (2025-10-30). "Nanotyrannus and Tyrannosaurus coexisted at the close of the Cretaceous". Nature. 

Additionally, calculations based on this Tyrannosaur’s sleek, fast, build, having projected it to be one of the fastest Dinosaurs, reaching top speeds in excess of 50 miles/hour. It would also have the capacity to run for longer based on the assumption that it has a bird-based respiratory tract, allowing it to breathe in and out at the same time, always supplying the lungs with oxygenated air.  

Its speculated that it was a pack hunter and lived in groups of 2-5. It used its group in numbers to overwhelm bigger animals. It would also be capable of taking smaller prey down by its self. These assumptions are primarily made due to gregarious natures found in similar small tyrannosaurids, such as Albertosaurus and Gorgosaurus.

 References 

Category:Cretaceous dinosaurs
Category:Tyrannosaurids