Metro has been digging the Purple Line extension and, as they expected, they've made some pretty interesting discoveries. The latest came during work on the Wilshire/La Brea stop. This recent find is the first time they've found mammal remains in this particular part of the project.

According to Metro, crews found a three-foot piece of a tusk and tooth fragments belonging to a mastodon just before Thanksgiving. And on Monday, they found a partial skull and tusks of either another mastodon or a young mammoth. The findings were both made about 15 feet below street level in the southwest corner of Wilshire and La Brea.

Metro spokesman Dave Sotero told the L.A. Times that the fossils are from the Ice Age, and at least 10,000 years old.

"We've unearthed and we've preserved L.A.'s prehistoric past as we build its future," Sotero said.

Previously, Metro uncovered a number of fossils while digging the Wilshire/Fairfax station near Wilshire Boulevard and Ogden Drive. These particular fossils included a species of clam that is still around today, a finding that indicates that at some point, California had a cold water climate similar to the Pacific Northwest.

In a video produced by Metro, Kim Scott, Asst. Project Manager at Cogstone, said, "Fossils tell us exactly what was going on with the environment 300,000 years ago. In addition to the fossils, we've also been recording sediments as we go down the shaft. And that information gives us our first three-dimensional look at what's below La Brea, so this is great to actually have this data and it's going to be used by scientists."

The mastodon has been extinct for about the last 10,000 years. They were over 7 feet tall and had huge curved tusks.

According to the La Brea Tar Pits & Museum:

The American mastodon was a distant relative of the ancestors of the elephant. During the Pleistocene, it ranged form Alaska to Florida. Mastodons differ from mammoths by their smaller size and lower-crowned ridged teeth.

The Pleistocene was 2,588,000 to 11,700 years ago.