Hundreds of fossils have been discovered under a California high school – in a find that is rewriting the state’s history.

San Pedro High School in Los Angeles County was under construction when workers unearthed fossils that are nearly nine million years old.

Workers paused construction at the site while researchers recovered 80 percent of the mᴀssive collection which included parts of whales and birds and teeth from saber-toothed salmon, megalodon sharks and other fish.

The finding suggests that Southern California was once underwater and could reveal the possibility that there was a now-extinct island to the west of the site.

Construction workers discovered fossils buried under San Pedro High School in Southern California that are nearly nine million years old

Fossils that had remained at the site for millions of years were found scattered across two locations on the San Pedro campus.

This led to a mᴀssive undertaking from June 2022 through July 2024 to remove the fossils before construction on the school could continue.

At one site, researchers at Envicom Corporation, which was contracted to monitor and advise the dig, found a bone bed that dated back to the Miocene era, about 8.7 million years ago and a shell bed from 120,000 years ago in the Pleistocene era.

‘It’s the entire ecosystem from an age that’s gone,’ Wayne Bischoff, the director of cultural resources at Envicom Corp. told BBC.

‘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.’

Austin Hendy, an ᴀssistant curator at the Natural History Museum of Los Angeles County said the way the fossils were laid out painted an image of where the shoreline met the sea nine million years ago.

‘I could see the shoreline in three dimensions, and I could see all the fossils, all the organisms that were living on that shoreline and washing up on that beach,’ he told Business Insider.

The fossils included the bones of fish and marine mammals and teeth from megalodon sharks measuring up to seven inches long.

The megalodon was three times longer than a great white that can grow up to 20 feet long.

The fossils included bones of whales, birds and other marine mammals as well as the teeth of fish, the megalodon shark and the saber-toothed salmon

Teeth from the saber-tooth salmon were also discovered for the first time, having never been seen in Southern California before.

This mammal was a prehistoric salmon that had a pair of spiked teeth that sH๏τ out of the side of its skull.

The saber-toothed salmon measured 2.5 to 3 meters in length and weighed between 200 and 400 pounds.

While the majority of the fossils were of marine animals, the researchers also discovered the skull of a sandpaper bird that lived more than eight million years ago.

The finding suggested the bird would have visited an island west of the school and is changing how scientists view California’s geological history.

‘Seeing a shorebird, and also large numbers of shoreline horsetail plants, started me thinking of an island beach as the origin of all of the fossil material,’ Bischoff told Business Insider.

Excavations began at San Pedro High School (pictured) in June 2022 and continued through July 2024

The island might have disappeared over the millennia from the weight of volcanic debris emitted from eruptions.

This built up a canyon where the fossils were preserved and accumulated over time, while the area’s tectonic activity that caused earthquakes helped these fossil beds move closer to the surface.

‘The volcanic ash did have a lot of rare elements, such as iron, sulfur, and manganese, which coated and protected some of the fossil material,’ Bischoff told BBC.

‘It’s a real window into what the geography of the oceans and land were at the time when this occurred,’ Behl told the LA Times.

‘Even though that seems a long time ago, that has real impact upon everything we got today.’

Researchers are now testing the fossil’s mineral and chemical composition to learn more about how these animals fossilized and hope it can shed light on the atmosphere and conditions of prehistoric environments.

‘After their experience on this site, [scientists] have started looking for other extinct islands,’ Bischoff told the LA Times.

Behl added: ‘We got to find clues and piece those clues together.’

The fossils are being held at the Natural History Museum in Los Angeles but it has not been confirmed if they will go on display for the public.