During the construction of a dam in Fremont, California, a treasure trove of fossils have been uncovered which are estimated to be 20 million years old.
The first excavations began in 2011, and since then palaeontologists have found an array of marine fossils, evidence that the ocean once washed up far inland.
Fossils include scallops, barnacles, clams, teeth from a 40-foot shark as well as the teeth of a hippopotamus-like animal called a Desmostylus and nine whale skulls. Plant and animal fossils have also been uncovered with evidence of burrow marks too.
The $700 million Calaveras Dam replacement project is only scheduled to finish in 2018, so there’s a strong chance that researchers will add to their 500+ fossil list.