An undergraduate student from the University of Alberta has uncovered the fossilised remains of an Ornithomimus dinosaur with preserved tail feathers and soft tissue. The remarkable specimen is offering important insights into the plumage patterns of these ancient creatures, while tightening the linkages between dinosaurs and birds.
The 75-million-year-old fossil, discovered by paleontologist Aaron J. van der Reest in the Upper Cretaceous Dinosaur Park Formation of Alberta, is the first to show traces of preserved skin from the femur to the abdomen in a non-avian dinosaur. It's considered the most complete feathered dinosaur specimen found in North America to date, the details of which can now be found at the science journal Cretaceous Research.
Analysis of the fossil shows that Ornithomimidae — a genus of omnivorous bipedal dinosaurs — were not covered in feathers from head-to-toe. Like modern-day ostriches, their legs were bare.
(Credit: A. J. Reest et al., 2015)
"We now know what the plumage looked like on the tail, and that from the mid-femur down, it had bare skin," noted van der Reest in a release. "Ostriches use bare skin to thermoregulate. Because the plumage on this specimen is virtually identical to that of an ostrich, we can infer that Ornithomimus was likely doing the same thing, using feathered regions on their body to maintain body temperature. It would have looked a lot like an ostrich."
A flightless dinosaur, it stood 2m tall, and featured a small head with a toothless beak. The fossil is only the third ornithomimus specimen to exhibit traces of feathers, and it's shedding light on how certain animals adapt to different environments.
"We are getting the newest information on what these animals may have looked like, how they maintained body temperatures, and the stages of feather evolution," says van der Reest.
As science report Ivan Semeniuk points out in the Globe and Mail,
Birds are thought to have evolved from a different line of dinosaurs than ornithomimus. Rather than indicating direct ancestry, the new fossil suggests that many features recognised in bird feathers today were present long before, in a common ancestor to both ornithomimids and birds. Together with fossils found in China that date back to a similar period, the new discovery promises to clarify how and when such features emerged.
Indeed, this specimen also tightens the linkages between dinosaurs and birds, particularly with respect to theropods — carnivorous bipedal dinosaurs.
"There are so many components of the morphology of this fossil as well as the chemistry of the feathers that are essentially indistinguishable from modern birds," added study co-author Alexander Wolf.
Read the entire study at Cretaceous Research: "A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada".
[ Globe and Mail ]
Top image by Julius Csotonyi