ScienceDaily for September 27, 2010 reported on the possible development of jaws in vertebrates.
Lampreys are eel-like fish with no jaws and a "very strange skeleton compared to their cousins" with jaws, Medeiros said. But "when we looked carefully at how genes are used during the development of the lamprey head, we saw that the basic plan for a jaw is there, and that only a few genes likely had to be moved around to create full-blown jaws."
