Monday, July 7, 2014 | 8:15 a.m.FREMONT, Calif. — Giant teeth from a 40-foot-long shark and portions of what could turn out to be an entire whale skeleton are among the hundreds of fossils being carefully unearthed at a dam construction site in Silicon Valley. The San Jose Mercury News reports Monday that over 500 marine fossil specimens have been uncovered at the Calaveras Dam replacement project in Fremont, California. Most of the fossils are believed to be about 20 million years old, dating to the Miocene Epoch, when the ocean extended as far inland as Bakersfield. Scallops, clams, barnacles and the teeth of an extinct hippopotamus-like creature called a Desmostylus have all been dug up. Paleontologists will continue working with construction workers for the next two or three years on the massive job to replace the dam with one more capable of withstanding earthquakes.