In the foothills of the Sierra Nevada Mountains in California, paleontologists have uncovered a collection of fossils, including an eight-million-year-old mastodon skull with both tusks intact, a rhino skeleton, a giant tortoise, 600 petrified trees, and many more specimens. Dating back to the Miocene epoch, the site is considered one of the most significant fossil discoveries in California history, reports Andrew Chamings for SFGate.