Overview
- City crews found multiple limb bones, ribs and fragments about 12 feet below the surface during routine infrastructure excavation in Oceanside, and consulting paleontologist Joseph El Adli secured the site.
- El Adli led a multi-day rescue dig that removed bones encased in hard mudstone and encased the specimens in plaster field jackets for safe transport to a laboratory in Carlsbad.
- Paleontologists place the material in Member C of the Santiago Formation and estimate the fossils date to roughly 40–45 million years ago within the Uintan interval.
- Initial field assessment narrows the likely identities to two odd‑toed ungulate groups—a brontothere (so‑called “thunder beast”) or an amynodont (“swamp rhino”)—but confirmation depends on recovering skull or dental elements during lab preparation.
- The City of Oceanside is withholding the exact dig location for safety and site protection, and the specimens are expected to be stabilized, studied further, and ultimately accessioned by a museum for research and public display.