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Fossils Unearthed During Calaveras Dam Work near Sunol Regional Park

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Shark teeth like this one from C. megaladon, nicknamed "Mighty Mouth" have been found in the fossil beds at Sunol.

Shark teeth like this one from C. megaladon, nicknamed “Mighty Mouth” have been found in the fossil beds at Sunol.

It’s hard to imagine the ocean lapping at the base of the Sierra Nevada, but the Temblor Sea, a vast-inland marine environment, once covered our area. Populated by sharks of mythic proportions, hippo-like mammals called Desmostylia, and small baleen whales along with scallops, clams and other benthic fauna, the Temblor supported a variety of now-extinct life.

A fossilized baleen whale skull encased in "field dressing" plaster clearly shows the inner ear bones.

A fossilized baleen whale skull encased in “field dressing” plaster clearly shows the inner ear bones.

Some of these fossils are coming to light millions of years later as the Calaveras Dam Replacement Project, part of San Francisco Public Utilities Commission’s (SFPUC) $4.6 billion Hetch Hetchy Water System Improvement Program, is underway. Started in 2010, the new dam on Calaveras Creek near Sunol Regional Wilderness will provide over half the drinking water storage capacity for over 2.6 million SFPUC customers. The current dam is 89 years old and within 1,500 feet of the active Calaveras earthquake fault. It will be replaced with a more seismically stable dam by late 2018.

EBRPD naturalist staff examines fossils found in the Calevaras Dam retrofit at Sunol.

EBRPD naturalist staff examines fossils found in the Calevaras Dam retrofit at Sunol.

Paleontologists work hand-in-hand with the construction crew as part of the environmental compliance team and help to unearth and preserve significant fossil finds. The fossil beds they’re encountering are providing tantalizing glimpses into ancient ecosystems. Two SFPUC paleontologists came to talk with the naturalists at the East Bay Regional Parks and shared some of their findings. It was quite a special experience to see an ancient baleen whale skull encased in a plaster “field jacket” with its perfectly preserved petrosal (or ear bone capsule) exposed. The giant shark tooth from a species of Megalodon up close was stunning, too. These fossil finds are helping scientists to put together a paleo-ecosystem down to the level of rainfall and even the evolution and lineage of different plants and animals.

Check the Cal Academy’s website to find out more about our fascinating fossilized past. The University of California, Berkeley’s Museum of Paleontology has online exhibits that can also help you learn more. To find out more about the Calaveras Dam Replacement Project, visit the SFPUC website.

 

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Category: Biology

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About the Author ()

Sharol Nelson-Embry is the Supervising Naturalist at the Crab Cove Visitor Center & Aquarium on San Francisco Bay in Alameda. Crab Cove is part of the East Bay Regional Park District, one of the largest and oldest regional park agencies in the nation. She graduated from Cal Poly, San Luis Obispo with a degree in Natural Resources Management and an epiphany that connecting kids with nature was her destiny. She's been rooted in the Bay Area since 1991 after working at nature centers and outdoor science schools around our fair state. She loves the great variety of habitats stretching from the Bay shoreline to the redwoods, lakes, and hills. Sharol enjoys connecting people to nature with articles in local newspapers and online forums. Read her previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.
  • David Carlson

    All Cenozoic Era fossils since East Russia, central Alaska, the North American cordillera and the Caribbean Islands may be part of the aqueously-differentiated extended-scattered-disc dwarf planet that impacted in the North Pacific 66 Ma.