A recently discovered articulated partial skeleton of Ornithomimus from the Upper Cretaceous Dinosaur Park Formation of Alberta, Canada is remarkable in the extent and quality of preservation of integumentary structures including feathers. It is the first ornithomimid to preserve a tail bearing extensive plumaceous feathers that are slightly more elongate in comparison to those present on the remainder of the body. However, the underside of the tail and the hind limb distal to the middle of the femur appear devoid of plumage. Overall, the plumage pattern in Ornithomimus is similar to that of Struthio camelus (ostrich) and other large palaeognaths, indicating a probable function in thermoregulation. The specimen also preserves the body outline around the legs, including a skin contour anterior to the femur, analogous to skin webs in extant birds. Whereas the knee web of birds bridges the knee to the abdomen, in Ornithomimus it spans from the mid-femoral shaft to the abdomen, and is herein referred to as an anterior femoral web. This is the first report of such soft tissue structures in non-avian theropods. It may indicate that the resting position of the femur was positioned more anteroventrally in ornithomimids than in most theropods, and in that sense may have been transitional to the situation in modern birds.
Keywords: Feathered dinosaur; Ornithomimidae; Ornithomimus; Late Cretaceous; Alberta
|Reconstruction of Ornithomimus showing a plumage pattern that is consistent with both UALVP 52531 and previously described feathered specimens from Alberta ( Zelenitsky et al., 2012), as well as with modern ratite birds, collectively suggesting a thermoregulatory role in all cases. |
Artwork: Julius Csotonyi. DOI: 10.1016/j.cretres.2015.10.004
In conclusion, while UALVP 52531 is not the first feathered ornithomimid dinosaur from the Late Cretaceous of western North America, the quality and extent of feather preservation in this specimen is unparalleled. As such, it provides a much stronger basis for interpreting the most likely function of feathers in non-avian theropods, and a much-refined perspective of the biology and ecology of ornithomimids.
Aaron J. van der Reest, Alexander P. Wolfe and Philip J. Currie. 2016. A Densely Feathered Ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada. Cretaceous Research. 58; 108–117. DOI: 10.1016/j.cretres.2015.10.004
Ornithomimus dinosaur with preserved tail feathers and skin tightens linkages between dinosaurs and birds http://phy.so/365249627 via @physorg_com