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Possible remains of prehistoric 'thunder beast' discovered at construction site

0:24
City of Oceanside
Possible remains of prehistoric 'thunder beast' discovered at construction site
City of Oceanside
ByTristan Maglunog and Bill Hutchinson
September 24, 2026, 3:27 PM

The fossilized remains of a possible "thunder beast" have been found at a Southern California construction site, and paleontologists believe the bones are up to 45 million years old.

The "remarkable discovery" was unearthed this month in Oceanside, about 40 miles north of San Diego, by crews working on a city infrastructure project, according to a statement from the City of Oceanside.

"These significant fossil finds, which included several limb bones, ribs, and numerous other bones and fragments, were uncovered approximately 12 feet below the surface during routine excavation for a city infrastructure project," the city said.

Fossilized remains of a large, hoofed mammal that lived up to 45 million years ago have been discovered at a construction site in Oceanside, California, city officials announced, September 22, 2026.
City of Oceanside

Paleontologists analyzing the fossils believe they are from a large, hoofed mammal that walked the ancient floodplains of Oceanside 40 million to 45 million years ago, officials said.

The city did not reveal the exact location of the discovery, citing public safety and efforts to protect the integrity of the site.

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Joseph El Adli, a paleontologist who had been monitoring the site, immediately recognized the significance of the discovery and secured the area to begin additional excavations, according to the city.

Fossilized remains of a large, hoofed mammal that lived up to 45 million years ago have been discovered at a construction site in Oceanside, California, city officials announced, September 22, 2026.
City of Oceanside

"His team worked over a period of seven days to expose the fossil bones from beneath several tons of hardened mudstone and sandstone before encasing them in a plaster field jacket for safe transport to an off-site laboratory for eventual preparation," the city said.

The remains were found in an area the city referred to as "Member C of the Santiago Formation," a thick formation of sedimentary rock in northwestern San Diego County that dates to the Eocene Epoch and falls within the Uintan North American Land Mammal Age.

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Based on the size and shape of the dinosaur bones, Adli said the remains could be a Titanotheres, also known as a "thunder beast," or an Amynodon, also known as a "swamp rhino."

"Further examination of the bones once they have been fully removed from the rock that encases them should allow paleontologists to narrow down the precise identity of the Oceanside fossil discovery," city officials said.

The specimens are expected to ultimately be displayed in a museum collection, where they will be preserved and made accessible to the public and to other scientists for further study, the city said.

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