In the distant past, between 350 and 400 million years ago, a group of our fishy ancestors started crawling up on land. The fins that propelled them through the water gradually evolved into sturdy, weight-bearing limbs. Their hind legs connected directly to their hips, which became bigger. Swimming fish became walking, four-legged tetrapods, such as amphibians, reptiles, and mammals.

Scientists have studied the evolution of tetrapod limbs and skeletons in incredible detail, but other aspects of our invasion of land are less clear. How, for example, did our pioneering ancestors eat?

Many fish feed by sucking. As they open their jaws, a horseshoe-shaped bone called the hyoid pushes down on the floor of the mouth, expanding it, and creating a