We don’t know for sure, but the developmental change appears to be another example of dinosaurs undergoing significant changes as they approach sexual maturity. Then again, based upon the resting and brooding postures of other theropod dinosaurs, adult Ornithomimus could have used their proto-wings to cover their nests. Perhaps adult Ornithomimus used flashy arm feathers to strut their stuff in front of potential mates. “We infer that because these wing feathers are not showing up until later in life, they were used for reproductive purposes,” Zelenitsky said. Sex is probably behind the plumage change. One adult skeleton, lacking forearms, preserves fuzzy feathers, and “the second adult had markings on the forearm.” Together, the specimens indicate that adult Ornithomimus were mostly covered in fuzz but developed more complex arm feathers by adulthood. What the adults looked like comes from the two other specimens. “The one juvenile was completely covered in filamentous type feathers,” Zelenitsky said. The fact that the adult and juvenile animals had different kinds of plumage adds new evidence that coelurosaurs changed their fluffy coats as they aged. It was shocking to say the least.”īut there’s more to the find than simply adding another species of fluffy dinosaurs to the list. “They’re the first feathered dinosaurs from the Americas, and the first ornithomimosaurs with feathers, as well. “When we found these specimens,” Zelenitsky said, “we made the link to the 1995 dinosaur.” All those strange marks on the arms of the previously discovered Ornithomimus, Zelenitsky and colleagues argue, are traces of longer, shafted feathers.Įven though paleontologists expected feathery Ornithomimus, the discovery was still a surprise. But in 20 a juvenile and an adult Ornithomimus turned up with preserved tufts of filamentous feathers. In 1995, when Zelenitsky was a graduate student, paleontologists uncovered an articulated Ornithomimus with weird marks on its forearms. Zelenitsky enthusiastically explained the details to me by phone earlier this week. The spread of feathers hinted that some sort of plumage was present in the common ancestor of all coelurosaurs and therefore should have been inherited by the ornithomimosaurs, but, until now, no one had found direct evidence.Ī trio of Ornithomimus skeletons have finally confirmed what paleontologists expected. To date, evidence of feathers has been found in every coelurosaur lineage except one–the ornithomimosaurs. The Coelurosauria is a major dinosaur group that encompasses tyrannosaurs, compsognathids, ornithomimosaurs, alvarezsaurs, oviraptorosaurs, deinonychosaurs and birds. The prediction of fluffy Ornithomimus came from the spread of feathers on the coelurosaur family tree. In Sternberg’s time, these dinosaurs were thought to be scaly, but recent finds of so many feathery dinosaurs has raised the likeliehood that the “ostrich mimic” dinosaur was at least coated in some sort of dinofuzz.Ī family tree of Saurischian dinosaurs, showing lineages within this group with direct evidence for feathers. Sternberg in 1933, and it is one of the characteristic Late Cretaceous species found in Alberta, Canada’s fossil-rich Horseshoe Canyon Formation. Ornithomimus edmontonicus was initially described by famed bone hunter C.H. Zelenitsky’s downy dinosaurs are not newly discovered species. Even better, the specimens raise hopes that many more dinosaurs might be preserved with their feathery coats intact. In the latest issue of Science, University of Calgary paleontologist Darla Zelenitsky adds another enfluffled species to the dinosaurian ranks. I love it, and I’m especially excited about a discovery announced today. Since the discovery of the fluffy Sinosauropteryx in 1996, paleontologists have discovered direct evidence of fuzz, feather-like bristles and complex plumage on over two dozen dinosaur genera.
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