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