Nanotyrannus

Nanotyrannus ("tiny tyrant") is a genus of tyrannosaurid dinosaur, and is possibly a juvenile specimen of Tyrannosaurus. Represented only by a small skull (catalogue number CMN 7541), it was discovered by Charles W. Gilmore in 1942 and described in 1946 as a specimen of Gorgosaurus lancensis (now known as Albertosaurus). In 1988, the specimen was re-described by Robert T. Bakker, Phil Currie, and Michael Williams, the late curator of paleontology at the Cleveland Museum of Natural History, where the original specimen was housed and is currently on display. Initial research indicated that the skull bones were fused, and that it therefore represented an adult specimen. In light of this, Bakker and colleagues assigned the skull to a new genus, which they named Nanotyrannus for its apparently small size. However, subsequent work has cast doubt on this, and some paleontologists no longer consider it a valid genus—since the fossil was a contemporary of Tyrannosaurus rex, many paleontologists now believe it to be a juvenile T.rex, especially since the discovery in 2001 of a new Nanotyrannus specimen, nicknamed "Jane." The original Nanotyrannus specimen is estimated to have been around 17 feet (5.2 meters) long when it died. In 2001, a more complete juvenile tyrannosaur ("Jane", catalogue number BMRP 2002.4.1), belonging to the same species as the original Nanotyrannus specimen, was uncovered. In 2005, a conference on tyrannosaurs focused on the issues of Nanotyrannus validity brought about by the discovery of the Jane specimen, was held at the Burpee Museum of Natural History. Several paleontologists, such as Phil Currie and Donald M. Henderson, saw the discovery of Jane as a confirmation that Nanotyrannus was a juvenile T. rex or closely related species. Peter Larson, on the other hand, continued to support a separate genus for Nanotyrannus. The actual scientific study of Jane, set to be published by Bakker, Larson, and Currie, may help determine whether Nanotyrannus is a valid genus, whether it simply represents a juvenile T. rex, or whether it is a new species of a previously identified genus of tyrannosaur.

Bakker has stated he believes Nanotyrannus hunted in packs. Teeth from multiple Nanotyrannus have been found in the bones of herbivorous dinosaurs.