Here are two different lower jaws, one edentulous (without teeth) and the other with teeth. What taxon do they represent? This is not a giant vampire bat. You are familiar with this critter in some way, to some degree.
No partial credit for size-based guesses; some of you have gotten too good at that!
This is an essay question: Tell us what you can deduce from the images.
Good luck in the rush for the gold!