Detail of a Charles R. Knight mural depicting a family a mastodons.

Fossils often turn up in unexpected places. As people have dug swimming pools, tilled farms, blasted through mountains, and quarried the land for minerals traces of ancient life sometimes come to the surface, from isolated shark teeth to skeletons of our extinct hominin relatives. Even fossil graveyards are found this way every now and then, like the one found in a southern Pennsylvania quarry a little more than a century ago.

In late April 1907 William Jacob Holland, a paleontologist and director of Pittsburgh’s Carnegie Museum, received two very similar letters about a quarry near Frankstown, PA. In addition to the limestone they were after workers