They're each composed of three major segments — a common arrangement we see in loads of animals all the way back to fish, which anatomists refer to as " one bone, two bones, lots of bones and digits."

它们每个都由三个主要部分组成——这是我们在许多动物（包括一直到鱼）中看到的常见排列，解剖学家称之为“一根骨头，两根骨头，很多骨头和手指。”