{{Automatic taxobox | name = Ornithomimosaurs | fossil_range = Cretaceous, | image = Ornithomimosauria Diversity.jpg | image_upright = 1.15 | image_caption = Collection of seven ornithomimosaurs, clockwise from top left: Gallimimus, Anserimimus, Ornithomimus, Deinocheirus, Harpymimus, Struthiomimus and "Gallimimus mongoliensis" | taxon = Ornithomimosauria | authority = Barsbold, 1976 | subdivision_ranks = Subgroups | subdivision = *Haplocheirus?NedcolbertiaNqwebasaurusThecocoelurus?Valdoraptor? Macrocheiriformes Cuesta et al., 2021HarpymimusPelecanimimusShenzhousaurusOrnithomimoidea Marsh, 1890ArkansaurusHexingKinnareemimusDeinocheiridae Ornithomimidae | synonyms = *Deinocheirosauria Barsbold, 1976 Arctometatarsalia Holtz, 1994 }} Ornithomimosauria ("bird-mimic lizards") are theropod dinosaurs which bore a superficial resemblance to the modern-day ostrich. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia (now Asia, Europe and North America), as well as Africa and possibly Australia. The group first appeared in the Early Cretaceous and persisted until the Late Cretaceous. Primitive members of the group include Nqwebasaurus, Pelecanimimus, Shenzhousaurus, Hexing and Deinocheirus, the arms of which reached 2.4 m (8 feet) in length. More advanced species, members of the family Ornithomimidae, include Gallimimus, Struthiomimus, and Ornithomimus. Some paleontologists, like Paul Sereno, consider the enigmatic alvarezsaurids to be close relatives of the ornithomimosaurs and place them together in the superfamily Ornithomimoidea (see classification below). Description The skulls of ornithomimosaurs were small, with large eyes, above relatively long and slender necks. The most basal members of the taxon (such as Pelecanimimus and Harpymimus) had a jaw with small teeth, while the later and more derived species had a toothless beak. The fore limbs ("arms") were long and slender and bore powerful claws. The hind limbs were long and powerful, with a long foot and short, strong toes terminating in hooflike claws. Ornithomimosaurs were probably among the fastest of all dinosaurs. Like other coelurosaurs, the ornithomimosaurian hide was feathered rather than scaly. Feathers Unambiguous evidence of feathers is known from Ornithomimus edmontonicus, of which there are multiple specimens preserving feather traces. Deinocheirus and Pelecanimimus have been speculated to be feathered as well, the former due to the presence of a pygostyle, and the later due to possible impressions (otherwise taken to be collagen fibers). There is a debate on whether ornithomimids possessed the pennaceous feathers seen in Pennaraptora. Otherwise, a very ostrich-like plumage and feather range is known in one specimen of Ornithomimus. Classification Named by O.C. Marsh in 1890, the family Ornithomimidae was originally classified as a group of "megalosaurs" (a "wastebasket taxon" containing any medium to large sized theropod dinosaurs), but as