In 1890, the fossil-hunter Othniel Charles Marsh described a new species of dinosaur from Colorado. He only had a foot and part of a hand to go on, but they were so bird-like that Marsh called the beast Ornithomimus – the bird mimic. As the rest of Ornithomimus’ skeleton was later discovered, Marsh’s description seemed more and more apt. It ran on two legs, and had a beaked, toothless mouth. Despite the long tail and grasping arms, it vaguely resembled an ostrich, and it lent its name to an entire family – the ornithomimids—which are colloquially known as “ostrich dinosaurs”.
Now, the bird mimic has become even more bird-like. By analysing two new specimens, and poring over an old famous one, Darla Zelenitsky from the University of Calgary has found evidence that Ornithomimus had feathers. And not just simple filaments, but wings – fans of long feathers splaying from the arms of adults. (More technically, it had “pennibrachia” – a word for wing-like arms that couldn’t be used to glide or fly.)
The two new specimens were found in 2008 and 2009 by Frank Hadfield, a local businessman from Drumheller, Alberta. He sent them to the local Royal Tyrrell Museum of Palaeontology, where Zelenitsky examined them. One is a juvenile, around one year old, with a dense coat of short hollow filaments on its trunk and limbs. The second is an adult that’s missing its arms; it too had the same filaments on its neck, back and upper body.
Each filament measures up to 5 centimetres long and half a centimetre wide. These represent the earliest stage of feather evolution—they’re known as proto-feathers or, more evocatively, dino-fuzz.