Aviraptor
Aviraptor is an extinct genus of small accipitrid bird of prey known from the Oligocene of Poland. It contains one species, Aviraptor longicrus. It was named in 2020 by Gerald Mayr and Jørn Hurum based on a single nearly complete specimen. The genus name is derived from the Latin words "avis" meaning “bird” and "raptor" meaning “thief” and the species name is derived from the Latin words "longus" meaning “long” and "crus" meaning “leg”. "Aviraptor" closely resembles modern hawks of the genus "Accipiter" in overall size and proportions. Like some species of "Accipiter", it had long and slender legs . "Aviraptor" was very small for a bird of prey, with a body size similar to the modern tiny hawk "Accipiter superciliosus" and little sparrowhawk "A. minullus". The bill of "Aviraptor" was not as sharply hooked as in most modern accipitrids, but is similar in shape to the modern harrier-hawks of the genus "Polyboroides". The size and proportions of "Aviraptor" are most similar to those of species that hunt other birds. It was a contemporary of some of the earliest species of passerine and hummingbird, which may have been its prey. The coexistence of some of the earliest passerines and  hummingbirds with the earliest known bird-hunting raptor may indicate that "Aviraptor" evolved in response to the diversification of potential prey species. Despite the overall similarity between "Aviraptor" and "Accipiter", the two genera do not appear to be closely related: "Aviraptor" lived approximately 30–31 million years ago, whereas accipitrines are estimated to have evolved approximately 16–18 million years ago. Furthermore, "Aviraptor" differs from "Accipiter" in anatomical details such as the proportions of its second toe and the shape of the deltopectoral crest of the humerus.