Our skeleton is kind of strange. Most of it forms from the same tissue that makes things like our muscle and connective tissue. The exception is a big chunk of our face, like the jaws and nasal ...

The sympathetic nervous system was thought to have evolved with jawed vertebrates. But lampreys—jawless, parasitic fish that suck out the blood of their hosts—have a simple one, per recent research.

Neural crest cells are involved in the development of osteoderms (like those in crocodiles) and the plastrons of turtles, so it seems likely. Some sources say they're behind virtually all ...