Eocene-era hoofed mammal fossils unearthed in Oceanside excavation
Eocene-era hoofed mammal fossils excavated in Oceanside heading to museum display.
Event / Science
Oceanside Fossil Discovery
Extinct mammal remains from 40-45 million years ago discovered during infrastructure construction in Oceanside, California, likely from the Eocene Epoch.
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2026-09-25 to 2026-11-02 · UTC publication dates
Coverage begins 25 Sept, 03:04 UTC
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What happened
Fossil specimens to be transferred to museum for public display
The prepared fossil specimens are expected to be transferred to a museum collection for preservation and public display. Potential destinations include the San Diego Natural History Museum or the Los Angeles County Natural History Museum, where the fossils will be accessible to the public and available for further scientific study.
Fossilized remains of extinct hoofed mammal discovered in Oceanside, California
Construction crews uncovered fossilized remains of a large hoofed mammal during routine excavation for a water infrastructure project in Oceanside, California, approximately 12 feet below the surface. The fossils included several limb bones, ribs, and other fragments, with the largest bone exceeding 2 feet in length. The remains were found in the Santiago Formation, a sedimentary rock unit in northwestern San Diego County.
Paleontologist Joseph El Adli led excavation and fossil recovery efforts
Consulting paleontologist Joseph El Adli discovered the first fossil fragment on August 31 and led the excavation process. His team worked for approximately seven to ten days to expose the fossil bones encased in hardened mudstone and sandstone, then encased them in plaster field jackets for transport to a laboratory in Carlsbad for preparation and study.
Extinct mammal fossils identified as possible Brontotheriidae or Amynodon species
Paleontologists analyzing the Oceanside fossils determined they likely belong to either a Brontotheriidae (thunder beast), a massive hoofed mammal with a deep chest and pronounced shoulder hump, or an Amynodon (swamp rhino), a semi-aquatic herbivore distantly related to rhinos. The fossils date to approximately 40 to 45 million years ago during the Uintan North American Land Mammal Age of the Eocene Epoch.
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