"A park ranger wandering through a petrified forest in California has unearthed a trove of prehistoric fossils, including a stunningly preserved mastodon skull and the remains of a 400-pound (181 kilograms) monster salmon, SFGate reported." Source: Live Science.
"Paleontologists unearthed dozens of fossil species near the Mokelumne River watershed in the foothills of the Sierra mountains southeast of Sacramento. The fossil site, which dates back roughly 10 million years to the Miocene epoch, is one of the most significant such troves ever discovered in the Golden State."
Comment: It's hard to imagine, but these prehistoric animals lived at a time when there were no humans in the world. Assuming our current picture of evolution is correct, the apes had just started to appear in the Old World at the beginning of the Miocene and the first human ancestors only began to diverge from the ancestors of modern chimpanzees near the end of the epoch. According to researchers, the region where these fossils were discovered was "an oak forest fringed by an ancient ocean" in the Miocene. If you ask me, California would've been a better place to live back then than it is today.