Averostrans

Averostrans, also called bird snouts or bird snouted dinosaurs, are theropod dinosaurs in the clade Averostra (meaning "bird snout") which includes most theropod dinosaurs, namely Ceratosauria and Tetanurae, and represent the only group of post-Early Jurassic theropods. Both survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians, megaraptorans, an incertae sedis group within Tetanurae, and 2 groups of tetanurans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only 1 subgroup of Maniraptoriformes, Aves (birds), survived the extinction event and persisted to the present day.

1 important diagnostic feature of Averostra is the absence of the 5th metacarpal. Other saurischians retained this bone, albeit in a significanty reduced form.