How Is the Human Skeleton Similar to a Snake Skeleton?

Humans and snakes both have skulls, backbones and ribs that support and protect the softer structures in the body. Humans and snakes are each highly derived descendants of a common ancestor, so many features of their skeletons are analogous to each other, albeit heavily modified.

Humans and snakes both have skulls that contain brains and support most of the animals' sense organs, such as eyes and noses. Both have jawbones, though mammalian jaws are very simple, and reptilian jaws are complex arrangements of bone and cartilage. Humans and snakes both have teeth, although the number and types of each set vary between species, and even from one individual to another.

Snakes and humans each have identifiable neck, upper back and lower back vertebrae, and the bones of the spine are recognizably similar in form and function. Both types of bone are ring-shaped, with central gaps to support the passage of the spinal cord. Snakes usually have many more vertebrae than humans, and most of the bones in the vertebral column support a set of ribs. Humans also have ribs, though they are fewer in number than snakes', and all are attached to the bones of the upper back. A few snake species, such as boas, have structures analogous to hips and hind legs, but these are vestigial and are greatly diminished in size.