Calaveras Dam - The Real 'Shark Tank'

Crews constructing the SFPUC’s new Calaveras Dam in the East Bay uncovered a geologic layer that happened to contain thousands of fossils. Through a cooperative agreement with the University of California Museum of Paleontology (UCMP; Berkeley, CA), those fossils are now being cleaned, analyzed, and catalogued.

“We transferred all of the fossil specimens to UCMP this year,” said JT Mates-Muchin, the SFPUC’s Environmental Compliance Manager who helped broker the agreement. “Fossils are a non-renewable resource. It is important that they are carefully catalogued and preserved for scientific research.”  

 A Megalodon Shark Tooth Being Scanned in the Lab.

The lead researcher and lab manager at UCMP, Cristina Robins, and her team are beginning to tease information out of the fossils.   Fifteen million years ago, the site of Calaveras Reservoir was located at the mouth of a vast inland sea that stretched into the Central Valley.  Just like in the seas of today, there was a lot of plant and animal life throughout. When they died, they left a fossil record.

This included sharks, lots of sharks. More than 2,000 shark teeth have been found from 35 species. These include many from requiem and mako sharks. Some teeth from the 35-foot megalodon shark have turned up as well. What do these shark teeth tell us?

1. The area around Calaveras Dam was once completely submerged by water.
2. The depth of the ocean could have been as deep as 700 to 1,000 meters.
3. The distribution of species is similar to fossil locations as far as way at Gatun, Panama.
4. Calaveras has a higher diversity of sharks than other sites.

At this point the paleontologists have only begun to scratch the surface of the Calaveras fossils, no pun intended.

The teeth from 35 different species of shark have been found at the Calaveras Dam Replacement Project.

We look forward to learning more secrets about the Bay Area’s past through these amazing fossils.

Keep up to date on the Calaveras fossils through the UCMPFacebook Page.

A 30 foot long predator left its tooth at Calaveras Dam. The Megaladon tooth is being analyzed at UCMP.

 See you around the Valley!

Fossils from the Calaveras Dam Replacement Project Find their New Home

The San Francisco Public Utilities Commission (SFPUC) has been working since 2011 to build a replacement Calaveras Dam out of seismic concerns for the existing 93-year-old dam in the Sunol Valley.

To make space for the new earth and rock-fill dam, the Calaveras Dam Replacement Project has had to move almost 10 million cubic yards of soil and rock. While moving all this earth, the project team began to find what has been called one of the greatest fossil finds in the Bay Area in decades.

To date more than 1,300 specimens have been discovered. Most them are fossils from an ancient ocean and beach area approximately 15 to 20 million years ago. Water covered much of California back then, and an inland ocean extended to the Central Valley.

Many of the fossils are high-quality specimens that can be used to further research into evolution or global change. (UC Berkeley photos by Sara Yogi)

Amongst the vertebrate fossils are marine mammals, like baleen whales or Mysticetes and toothed whales and dolphins or Odontocete; and Desmostylus, an herbivorous hippo-like marine mammal), seals or sea lions, sharks, and bony fish, such as halibut.  The invertebrates include scallops (some as big as a dinner plates), clams, snails, cockles, mussels, crabs, and barnacles. The team believes it has found a new species of whale among the dozens of whale skulls found.

Researchers have pieced together the jawbone from a 15- to 20 million-year-old whale. 

(UC Berkeley photos by Sara Yogi)

Researchers can tell this area was near to shore because they have also found plant material that washed into the ocean from land, including pine cones, palm trees, leaves, and wood. They can tell that the Bay Area was warmer back in this time, and the ocean teemed with life.

Through an agreement between SFPUC and the University of California Museum of Paleontology (UCMP) the entire collection of fossils will now be housed within the UCMP collections. The fossils represent California’s fossil heritage and as such, belong to all the citizens of California, and will be managed on their behalf by the University of California Museum of Paleontology. 

The UCMP assembled a team to manage this collection, including a Lab Manager – Dr. Cristina Robins, many undergraduate students, two graduate students per semester, and volunteers.

Graduate student Mackenzie Kirchner-Smith uses a brush to spread adhesive over a fossil found during the Calaveras Damn replacement project. (UC Berkeley photos by Sara Yogi)

Dr. Robins and her team painstakingly chip away the rock from the fossilized bone to identify each specimen. It is laborious work. They often find new specimens inside the rock blocks around other specimens. More fascinating fossil discoveries lay ahead for the UCMP team.

Fossils waiting to be released from rock fill the small lab located at UCMP.

And we at the SFPUC know the fossils are in excellent hands.

See the video and read more here:

See you around the Valley!