Ancient 45-million-year-old mammal fossils discovered in California

Construction crews in Oceanside uncovered the fossilised remains approximately 12 feet below the surface while working in the Santiago Formation, a geological layer known for preserving ancient life. The bones belong to a sizeable hoofed mammal that roamed North America millions of years ago, according to paleontologists examining the discovery.

Researchers are currently conducting detailed analysis to determine the precise species represented by the fossils. The remains may belong to a thunder beast, a large extinct ungulate, or alternatively to a swamp rhino, an early relative of modern rhinoceroses that inhabited the continent during the early Cenozoic era.

The Santiago Formation has previously yielded valuable fossils from the Eocene epoch, a period spanning from roughly 56 million to 34 million years ago. The discovery adds to the growing body of paleontological evidence documenting California's ancient ecosystems and the diverse megafauna that inhabited the region during the early Tertiary period.

Paleontologists expect to complete their analysis in the coming months, which may provide fresh insights into the evolution and distribution of large mammals in North America during this critical period of mammalian diversification.