That's actually the only venomous turtle in the US...no, just kidding! My vote would be a Florida Mud turtle (Kinosternon subrubrum steindachneri). It's a subspecies of the common Eastern Mud turtle. If it only has one hinge on its plastron, it's probably a Loggerhead Musk turtle. It looks much more like a Mud to me. They do typically have one thing in common with snappers...they bite, and they stink! But isn't that what we love about them?