"It's incredible to think that a piece of history this rich was resting in a schoolyard all this time." In 2002, coal miners in Queensland, Australia, uncovered a rock slab with several three-toed footprints preserved in it.

This schoolyard boulder with ancient footprints is revealing a vibrant moment in Australia's prehistoric past.

A slab of rock at an Australian high school, a boulder in a parking lot, and a bookend in a private collection feature 200-million-year-old dinosaur footprints.