California construction crews are used to finding fossils when excavating, and such was the case recently when a crew hit the ground running in 2013 at the new Bay Area Calaveras Dam. Still, they hadn’t expected to find as many as they did.
Calaveras Dam, 93 years old, is only approximately a thousand feet away from Calaveras Fault; too close for comfort, the proximity was a cause for earthquake safety concerns. The dam holds the Calaveras Reservoir that holds about 40 percent of the region’s water supply. As the largest reserve in Bay Area and with 2.7 million residents relying on its water, the stability of this dam is quite important. After some studying, it was decided to rebuild the dam right beside its current location.
CNN reported that the excavation of the dam needed 10 million cubic yards of soil and rock to moved and during the first step of the project, shell fossils were found at the site. As such, the crew included a paleontologist who monitored and documented the excavation to ensure preservation around anything that was found. While fossils were expected, the amount they found, and the variety was not. In fact, the area proved to be a site for a treasure trove of fossils, giving insight around the life of the region 15-20 million years prior; with the most complete fossil collection found in this area for over half of a century. The combination of both animal and plant fossils has provided a clear insight of what area conditions were once like, so many years ago.
A variety of fossilized pine cones and palm trees were found, tons of invertebrates including crabs and snails, as well as whale skulls and shark teeth. Evidence was also discovered around a past unknown species of fossilized baleen whale – and researchers expect to find additional new species as they continue.
Still, to date they have collected about twenty whale skulls, all measuring at about three feet long. This is quite unusual for a ‘salvage’ project (as they are called), where researchers excavate fossils from active construction sites.
The study team was quite surprised by the quantity and quality of fossils collected. Currently, there are individual teeth found from a Desmostylus (hippo-type animal), as well as a seal. The team has gathered evidence of four differing species of baleen whales, and a minimum of two, toothed-whale species. The team almost has their largest whale finding completed with a skull that spans five feet, some ribs, and 17 vertebrae.
Even more interesting is that these fossil findings are the first-ever collected from this specific region of East Bay, which has become one of the richest marine mammal sites for north California.
Millions of years ago, water seemingly covered this region; whales roamed over the areas that people work and live in now, within Oakland and Berkeley communities, and huge megalodon sharks swam within San Jose. Desmostylus would have been swimming the coastline filled with pine and palm trees, where seals would be splashing along with them in the water.
With the number of fossils being found, the study will take some time. The project ends in July of next year and researchers are busy doing what they can until that date. When the summer of 2019 hits, what is left behind will be available and open for others to review.