Maniraptorans

Maniraptorans are a clade of small- to medium-sized coelurosaurian theropod dinosaurs that includes birds and their closest relatives. In modern usage, Maniraptora is defined as the last common ancestor of oviraptorosaurs and birds and all of its descendants. Members are united by a suite of features adapted for a more agile forelimb and advanced plumage, including a partially opposing, curved hand and a semi-lunate carpal that enhances wrist flexibility, as well as evidence of feathers in numerous species. The group encompasses several major lineages: the dromaeosaurids (raptors) such as Velociraptor and Deinonychus; troodontids such as Troodon; oviraptorosaurs; therizinosaurs such as Therizinosaurus; and Avialae, the clade that includes Archaeopteryx and all modern birds.

Fossils show a wide temporal and ecological range, with remains dating from the Late Jurassic to the end of the Cretaceous. Maniraptorans occupied diverse niches, from small, agile predators to herbivorous therizinosaurs and omnivorous oviraptorosaurs. Feathers are preserved in many taxa, suggesting a common origin of plumage within the group and the evolution toward flight in the avian lineage. The birds are the only surviving maniraptorans, having diversified into the present day after the Cretaceous-Paleogene extinction event.

Taxonomically, the exact boundaries of Maniraptora have varied with new discoveries and analyses, but the group is widely recognized as the closest living relatives of birds, bridging theropod dinosaurs and modern avians.