Fossil Friday!

On slow and rainy days over at the paleontology museum, I often slip into the back archives to poke around. Opening drawers can be a mystery in itself—will I find myself diving into a cabinet full of marsupial teeth, camelops bone fragments, T. rex toes? The fossil for this week is from one of those adventures—it's a pile of skull fragments, only identified by its family. But I think you'll know the family right away! Can you tell me what it is? Where was it found? When it dates back to?

Also, bonus points to the first person who can find me the wackiest Youtube video featuring a creature from this family. I'm guessing there are going to be a few!