ArchaeopteryxArchaeopteryx (ˌɑːrkiːˈɒptərᵻks; old-wing), sometimes referred to by its German name, "Urvogel" ( Primeval Bird), is a genus of avian dinosaurs. The name derives from the ancient Greek (archaīos), meaning "ancient", and (ptéryx), meaning "feather" or "wing". Between the late 19th century and the early 21st century, Archaeopteryx was generally accepted by palaeontologists and popular reference books as the oldest known bird (member of the group Avialae). Older potential avialans have since been identified, including Anchiornis, Xiaotingia, and Aurornis.
ConfuciusornisConfuciusornis is a genus of basal crow-sized avialan from the Early Cretaceous Period of the Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago. Like modern birds, Confuciusornis had a toothless beak, but closer and later relatives of modern birds such as Hesperornis and Ichthyornis were toothed, indicating that the loss of teeth occurred convergently in Confuciusornis and living birds. It was thought to be the oldest known bird to have a beak, though this title now belongs to an earlier relative Eoconfuciusornis.
MicroraptorMicroraptor (Greek, μικρός, mīkros: "small"; Latin, raptor: "one who seizes") is a genus of small, four-winged dromaeosaurid dinosaurs. Numerous well-preserved fossil specimens have been recovered from Liaoning, China. They date from the early Cretaceous Jiufotang Formation (Aptian stage), 125 to 120 million years ago. Three species have been named (M. zhaoianus, M. gui, and M. hanqingi), though further study has suggested that all of them represent variation in a single species, which is properly called M.
DromaeosauridaeDromaeosauridae (ˌdrɒmi.ə'sɔrɪdiː) is a family of feathered Coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek δρομαῖος (), meaning 'running at full speed, swift', and σαῦρος (), meaning 'lizard'. In informal usage, they are often called raptors (after Velociraptor), a term popularized by the film Jurassic Park; several genera include the term "raptor" directly in their name, and popular culture has come to emphasize their bird-like appearance and speculated bird-like behavior.
DeinonychusDeinonychus (daɪˈnɒnɪkəs ; ) is a genus of dromaeosaurid theropod dinosaur with one described species, Deinonychus antirrhopus. This species, which could grow up to long, lived during the early Cretaceous Period, about 115–108 million years ago (from the mid-Aptian to early Albian stages). Fossils have been recovered from the U.S. states of Montana, Utah, Wyoming, and Oklahoma, in rocks of the Cloverly Formation and Antlers Formation, though teeth that may belong to Deinonychus have been found much farther east in Maryland.
Crown groupIn phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants.
