Coelurosauria /sɨˌljʊərəˈsɔriə/ (from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished. Nonetheless, it is still a diverse group that includes compsognathids, tyrannosaurs, ornithomimosaurs, and maniraptorans; Maniraptora includes birds, the only dinosaur descendants alive today. Most feathered dinosaurs discovered so far have been coelurosaurs; Philip J. Currie considers it probable that all coelurosaurs were feathered.[2]


All coelurosaurs were bipedal, and most were carnivores, though many groups exhibited a more varied diet including insectivory (Alvarezsauridae), omnivory (Oviraptoridae and Troodontidae), and herbivory (Therizinosauridae).[3] The group includes some of the largest (Tyrannosaurus) and smallest (Microraptor, Parvicursor) carnivorous dinosaurs ever discovered. Characteristics that distinguish coelurosaurs include: a sacrum (series of vertebrae that attach to the hips) longer than in other dinosaurs a tail stiffened towards the tip a bowed ulna (lower arm bone). A tibia (lower leg bone) that is longer than the femur (upper leg bone).