During construction of the Metro Purple Line extension, workers stumbled across the remains of an ancient elephant.
The first discovery, made just before Thanksgiving, was of a 3-foot section of tusk fragments, as well as fragments of a mastodon tooth, found at a depth of 15 feet at the Wilshire and La Brea excavation site, said Metro spokesman Dave Sotero.
Late afternoon Monday, a paleontological monitor hired to look out for bones and fossils came across a partial skull and tusks, believed to belong to an ancient elephant, Sotero said. The second discovery was made within about 10 feet of the first.
The mammal fossils that were found are at least 10,000 years old and are from the ice age, Sotero said. Further analysis of the teeth will help paleontologists identify what type of ancient elephant it was, Sotero said.
"This is significant; it's the very first mammal fossils that have been found on the Purple Line extension project," Sotero said. "We've unearthed and we've preserved L.A.'s prehistoric past as we build its future."
A plaster cast was placed around the fossils, and they will later be removed from the site by a paleontological consultant that works with Metro on the Purple Line project.
Once the fossils are identified, analyzed and preserved, they will be provided to the Natural History Museum in Exposition Park, Sotero said.
The finds are not expected to slow construction, Sotero said.
"We have processes in place already that compensate for when we do find these types of fossils," Sotero said.
Staff at the nearby La Brea Tar Pits and Museum anticipate that workers will likely find more fossils when they begin their excavation of the Wilshire and Fairfax station across the street.
"We live in a very fossil-rich place," said Emily Lindsey, assistant curator at the museum. "There's a number of opportunities for paleontologists just right here under L.A."
Discovering fossils is nothing new in this part of Los Angeles. The area around the Los Angeles County Museum of Art is considered one of the richest ice age fossil sites in North America.
Over the millenniums, petroleum from once-massive underground oil fields oozed to the surface, forming bogs that trapped and killed unwary animals and then preserved their skeletons.
In 1986, construction of LACMA's Japanese Pavilion was shut down for six weeks when excavation uncovered a major deposit of invertebrate fossils.
This is the latest in a series of finds made during digging for the subway.
Since 2014, paleontologists recovered mollusks, asphalt-saturated sand dollars, pieces of driftwood and Monterey cypress cones, and a rock embedded with what appears to be part of a sea lion's mouth, among other things.
When Metro was digging the Red Line subway in the 1980s, workers collected thousands of fossil specimens and preserved them.