Platypus x-rays show shadows of its “reptilian” ancestry

Platypuses belong to an ancient group of mammals, the monotremes. Today, these are the only living mammalian species to lay eggs, and the group also includes echidnas. But, as the x-rays of┬áDr Larry Vogelnest show, the platypus retains several skeletal features which link it to its distant ancestors (often called reptiles, but more technically referred…