Construction Project Unearths Millions of Fossils Beneath a Los Angeles High School

Millions of years ago, Los Angeles was underwater. In fact, the land where the city lies today was submerged for most of its geological history. And now, a local high school has gotten a powerful reminder of that fact: Construction work at the San Pedro High School on the Palos Verdes Peninsula revealed millions of marine fossils beneath its campus that testify to the region’s aquatic prehistory.

“There’s never been this type of density of fossils ever found at a site like this before in California,” Wayne Bischoff, the director of cultural resources at Envicom Corporation who managed the excavated fossils, tells the Los Angeles Times’ Jireh Deng. “It’s the largest marine bone bed found in Los Angeles and Orange counties.”

The excavation work, which began in 2022, revealed three distinct fossil sites: a layer of 120,000-year-old shells from the Pleistocene epoch, an 8.7-million-year-old bonebed containing fish and marine mammal remains from the Miocene epoch and an 8.9-million-year-old layer of phosphorous-rich rock that revealed evidence of volcanic activity.

Now that the construction is completed, scientists have begun the arduous process of studying the tons of paleontological material unearthed from the site, including remains of sea turtles, birds, fish, sharks, dolphins, whales, invertebrates, plants and the megalodon, the largest shark to ever exist. The fossils represented more than 200 species, including some that had never been seen in Southern California before, such as the saber-toothed salmon.

The deepest bonebed layer dates to a time that’s underrepresented in the fossil record of the Palos Verdes Peninsula. “The material is unique in that it also has a large amount of coprolites—fossilized scat that contains dozens of fish bones,” wrote Bischoff in a summary of the findings shared with Smithsonian magazine.

The fossil discoveries at San Pedro High School are almost 9 million years old and a game-changer for the @NHMLA. These unique bonebeds found in the region are vital for future research, education and understanding of aquatic life in prehistoric Southern California. pic.twitter.com/lubcICBHy1

— Alberto M. Carvalho (@LAUSDSup) September 9, 2024

Using these newly discovered remains, researchers at the Museum of Natural History of Los Angeles County, along with Milad Esfahani, a San Pedro High School student and museum intern, are now analyzing the area’s geologic past.

“We’ve moved away from just describing what we find, identifying new species and making lists of things … to really trying to understand how ecosystems function, how they’ve changed through time,” Austin Hendy, a paleontologist and assistant curator at the museum, tells LAist’s Mariana Dale.

Because of the shoreline-related fossils—including coastal plants, driftwood and shorebirds—the team suggests the area was home to a prehistoric island, which is now long gone. Millions of years ago, a storm could have channeled organic debris east from the island and into an underwater canyon, where a layer of mud effectively sealed it into sediment that was only revealed in more geologically recent times. Hendy also hypothesizes that there was “volcanism going on somewhere in the vicinity,” he tells ABC7’s Amanda Palacios. Experts are now looking for signs of more extinct islands.

“We’re kind of like detectives,” Richard Behl, a geologist at California State University, Long Beach, who is studying the composition of the fossils, tells the Los Angeles Times. “We got to find clues and piece those clues together.”

He explains that the Miocene-era fossils are encased in diatomite, a sort of fossilized algae, which signals that the prehistoric environment was nutrient-rich and capable of supporting a complex ecosystem.

The rarity of the discovery has surprised the school’s students—most of L.A.’s paleontological history is sealed away beneath concrete, per LAist.

“I thought this stuff was something that never happens, especially around here,” Taya Olson, a San Pedro High School student, says to ABC7. “It only happens in textbooks.”

The fossils have now been distributed to various institutions for future research, including the Natural History Museum of Los Angeles County, Cabrillo Marine Aquarium, Los Angeles Unified School District and Cal State Channel Islands. Researchers hope the discovery could unveil even more information about Southern California’s prehistoric ecology.

“It’s the entire ecosystem from an age that’s gone,” Bischoff tells LAist. “We have all this evidence to help future researchers put together what an entire ecology looked like nine million years ago. That’s really rare.”

Margherita Bassi | READ MORE

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.