Inside the mouth of every child is a terrifying double row of teeth. Not that you'd ever know it — muscle, skin and bone prevent most of us from ever catching a glimpse of this extra dentition. Here's your chance to get a close-up look at what lies beyond the gum line.
Although the ancient hominid Paranthropus boisei has earned the nickname "Nutcracker Man", his actual diet was quite a bit softer. Unlike any other known human ancestor, this ancient hominid's powerful jaw and huge molars were actually used to eat grass.
The marsupials and monotremes that are now found primarily in Australia represent a sort of evolutionary middle ground, mixing together their mammalian features with those of reptiles or amphibians. One ancient marsupial represents a particularly weird case of convergent evolution.