Modern crocodilians (a small remnant of a once large and successful group) are (along with birds) the only living members of the archosaurian line of reptiles that gave rise to both groups. All crocodilians (like the American alligator shown above) have well-reinforced skulls with massive jaw musculature that provides a wide gape and rapid, powerful closure over prey. Their many sharp teeth, which are set in sockets (thecodont), are designed for gasping but not for chewing.  A muscular gizzard (like that of birds) finishes the job of grinding up food with the help of swallowed stones and other items.