The University of California Museum of Paleontology, at the University of California, Berkeley campus, stepped up to the challenge. The school spent $500,000 to reopen a fossil prep lab. "UCMP has been a great partner in that endeavor," Rhodes said.
"They have assembled a tremendous team and lab to prepare and categorize the fossils and make them available for future generations."
Among the finds were numerous fossilized palm trees and pine cones, hundreds of invertebrates including snails and crabs, shark teeth and whale skulls. There was also evidence of a previously unknown species of fossilized baleen whale. As the researchers continue their work, they expect to find more new species.
They have upwards of 20 whale skulls, each about 3 feet long. This is highly unusual for a "salvage" project, in which scientists try to excavate fossils from an active construction site that may be damaged.
"Thus far we have made significant progress on five complete skulls, and quite a few individual bones," Cristina Robins, senior museum scientist at the museum and head of the the project, wrote in an email.
"There are individual teeth from Desmostylus [a hippo-like creature] and seal. We have evidence for 4 different baleen whale species, and at least 2 toothed whale [dolphin or orca-like] species. Our largest whale is actually the most complete -- we have a 5-foot skull and 17 vertebra, plus some ribs," she wrote.
Robins said she was surprised by the quality, as well as the quantity, of the fossils.
Although the small invertebrates may seem less exciting, they help complete a time capsule of what life was like millions of years ago in what is now the Bay Area, especially the paleo-environment and climate, according to Robins.
"These are the first fossils ever collected from this particular part of the East Bay, and it has turned out to be one of the richest sites for marine mammals in northern California," she said.
"It is the first time that we have so many individuals of the same species of fossil whales from the same site. It is rare to find vertebrate, invertebrate and plant fossils that have been scientifically collected from the same rock units, so it will allow us to reconstruct the past environments with a level of detail that is very unusual for any site, and especially for ones on a construction site. Additionally, the plant fossils are terrestrial -- palm trees and pine trees -- preserved with the marine fossils. This shows us that the coastline was not far away."
Water covered much of the area millions of years ago. Where people live and work now, whales roamed over modern Berkeley and Oakland, and giant megalodon sharks were chasing prey in San Jose.
Desmostylus would have waded along a coastline that was decorated with palm and pine trees, while giant seals were splashing in the water.
Cleaning, preparing and studying this number of fossils takes time. The project will end in July 2019, so the researchers are documenting what they can find. They will do all they can until then, and that's when whatever is left will be open and available for others to study.
"We are really just beginning to understand the scientific significance of the finds," Robins said.
"This collection adds significantly to our knowledge of the paleontology of California from the Miocene -- about 15-20 million years ago. The quantity and quality of the fossils is extremely impressive, and that comes down to both luck and the skill and care of the mitigation paleontologists and the construction workers who often found the fossils."