Coelurosauria

Lore & Background

Coelurosauria was historically used as a dumping ground for all small theropods, but modern cladistic definitions restrict it to animals closer to birds than to Allosaurus. This reclassification moved large theropods like tyrannosaurids into the group. The clade's last common ancestor likely evolved an omnivorous diet, which may have contributed to its success; later lineages specialized into insectivores, herbivores, and carnivores. Most feathered dinosaurs discovered are coelurosaurs, and Philip J. Currie considered it likely that all coelurosaurs were feathered, though some skin impressions show pebbly, scaly skin.

Reader's Guide

Coelurosauria is significant as the clade that gave rise to birds, the only dinosaur lineage to survive the Cretaceous–Paleogene extinction event. Fossil evidence shows that coelurosaurian differentiation was virtually complete by the end of the Jurassic, with many lineages persisting until the end of the Cretaceous. The discovery of feathered coelurosaurs has revolutionized understanding of dinosaur integument and the evolution of flight. The group includes both the largest (Tyrannosaurus) and smallest (Microraptor, Parvicursor) known carnivorous dinosaurs. The study of coelurosaur endocrania has helped document the neurological transition from reptiles to modern birds. The clade's classification remains under revision, with recent analyses clarifying relationships among subgroups such as Tyrannoraptora and Maniraptora.

Did You Know?

• A portion of a tail belonging to a juvenile coelurosaur was found in 2015 inside a piece of amber.
• All known theropod dinosaurs from the Yixian Formation in Liaoning are coelurosaurs.
• The oldest unambiguous coelurosaurs are the proceratosaurid tyrannosauroids Proceratosaurus and Kileskus from the late Middle Jurassic.
• Feather-like structures have also been found in some ornithischian dinosaurs and pterosaurs, though they may have evolved independently.