Was Nanotyrannus a valid genus of the Tyranosaurids?
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
