Hold your arms out with your palm oriented vertically, as if you were trying to shake someone’s hand. Now without moving your forearm, bend your hand downwards towards the floor.  Unless you are freakishly flexible, you will only have managed to a measly acute angle. But if you were a bird, you could bend your wrist so that your hand pointed back towards your body. These incredibly flexible wrists allow birds to fold their wings and they help with flying. And many dinosaurs could do something similar.

Many older depictions of small raptors, including the Jurassic Park films, have them holding their arms in a zombie-like stance – arms out at the front and hands palms-down. More recently, artists have portrayed