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Ornithomimus with feathers from Upper Cretaceous of Alberta

Ben Creisler

A new paper:

Aaron J. van der Reest, Alexander P. Wolfe & Philip J. Currie (2016) [2015]
A densely feathered ornithomimid (Dinosauria: Theropoda) from the
Upper Cretaceous Dinosaur Park Formation, Alberta, Canada
Cretaceous Research 58: 108–117

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.