Fossils dated to 40–45 million years ago

Fossilized remains were discovered about 12 feet beneath the surface during excavation for a city water infrastructure project in Oceanside, California. The city first announced the discovery on September 22. Scientists have not yet determined exactly which animal the bones belonged to.

The fossils have been dated to roughly 40 to 45 million years ago, placing them within the Uintan North American Land Mammal Age.

The size and shape of the recovered bones have narrowed the possible identification to two extinct groups of odd-toed hoofed mammals.

Researchers need more anatomical evidence before making a precise identification. A skull, teeth or lower jaw would be particularly useful because those features can provide identifying clues that isolated limb bones cannot.

The exposed bones were protected inside a plaster field jacket. This fossil-recovery technique keeps fragile specimens together with some surrounding rock so they can be transported without breaking apart.

The fossils have been moved to an off-site laboratory. Specialists there will remove the remaining rock and stabilize the bones using conservation materials.