page_title: Ornithomimus
section_title: Feathers and skin
hierarchical_section_title: Ornithomimus / Description / Feathers and skin
caption_attribution_description: English: Life reconstruction of "Ornithomimus" sp. based on specimens from the Dinosaur Park Formation.
context_page_description: Ornithomimus is a genus of ornithomimid dinosaurs from the Late Cretaceous Period of what is now North America. Ornithomimus was a swift bipedal theropod which fossil evidence indicates was covered in feathers, equipped with a small toothless beak that may indicate an omnivorous diet. It is usually classified into two species: the type species, Ornithomimus velox, and a referred species, Ornithomimus edmontonicus. O. velox was named in 1890 by Othniel Charles Marsh on the basis of a foot and partial hand from the late Maastrichtian-age Denver Formation of Colorado, United States. Another seventeen species have been named since, though most of them have subsequently been assigned to new genera or shown to be not directly related to Ornithomimus velox. The best material of species still considered part of the genus has been found in Alberta, Canada, representing the species O. edmontonicus, known from several skeletons from the early Maastrichtian Horseshoe Canyon Formation. Additional species and specimens from other formations are sometimes classified as Ornithomimus, such as Ornithomimus samueli from the earlier, Campanian-age Dinosaur Park Formation of Alberta.
context_section_description: Ornithomimus, like many dinosaurs, was long thought to have been scaly. However, beginning in 1995, several specimens of Ornithomimus have been found preserving evidence of feathers. In 1995, 2008 and 2009, three Ornithomimus edmontonicus specimens with evidence of feathers were found; two adults with carbonized traces on the lower arm, indicating the former presence of pennaceous feather shafts, and a juvenile with impressions of feathers, of which were up to five centimetres in length, in the form of hair-like filaments covering the rump, legs and neck was also discovered. The fact that the feather imprints were found in sandstone, previously thought to not be able to support such impressions, raised the possibility of finding similar structures with more careful preparation of future specimens. A study describing the fossils in 2012 concluded that O. edmontonicus was covered in plumaceous feathers at all growth stages, and that only adults had pennaceous wing-like structures, suggesting that wings may have evolved for mating displays. In 2014, Christian Foth and others argued that the evidence was insufficient to conclude that the forelimb feathers of Ornithomimus were necessarily pennaceous, citing the fact that the monofilamentous wing feathers in cassowaries would likely leave similar traces.
  A fourth feathered specimen of Ornithomimus, this time from the lower portion of the Dinosaur Park Formation, was described in October, 2015 by Aaron van der Reest, Alex Wolfe, and Phil Currie. It was the first Ornithomimus specimen to preserve the feathers along the tail. The feathers, though crushed and distorted, bore numerous similarities with those of the modern ostrich, both in their structure and distribution on the body. Skin impressions were also preserved in the 2015 specimen, which indicated that from mid-thigh to the feet, there was bare skin devoid of scales, and that a flap of skin connect the upper thigh to the torso. This latter structure is similar to that found in modern birds, including ostriches, but was positioned higher above the knee in Ornithomimus than in birds.
caption: Life restoration of the plumage pattern suggested by specimens preserving feathers and skin
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