| EBMUD (East Bay Municipal Utilities District) ranger Greg Francek excavates a shell from the extinct giant tortoise Hesperotestudo at a locality he discovered on EBMUD property near Camanche Reservoir in 2020 (the site is obviously off limits to unauthorized visitors), western foothills of the Sierra Nevada. The ancient reptile resides in the upper Miocene to lower Pliocene Mehrten Formation, approximately 10 to five million years old. In less than a year, technicians had already recovered--in addition to giant tortoise shells and petrified woods--much Cenozoic mammalian skeletal material from proboscidean gomthotheres and mastodons, rhinoceroses, camels, tapirs, and horses. Photograph courtesy East Bay Municipal Utility District. |