Ice Age fossils, including mammoth, found at LA subway extension work

As part of the crew digging a subway extension under the streets of Los Angeles, Ashley Leger always keeps her safety gear close by. When her phone buzzes, she quickly dons a neon vest, hard hat, and goggles before climbing deep down into a massive construction site beneath a boulevard east of downtown.

Earth-movers are diverted, and Leger gets on her hands and knees and gently brushes the dirt from a spot pointed out by a member of her team. Her heart beats faster because there's a chance she'll uncover what she calls "the big find."
Leger is a palaeontologist who digs for fossils in the middle of a city rather than an open plain or desert. She works for a company contracted by Los Angeles transportation officials to keep palaeontologists on hand as workers extend a subway line to the city's west side.

"They're making sure that they're recovering every single fossil that could possibly show up," Leger says of her team of monitors. "They call me anytime things are large and we need to lead an excavation."

Since work on the extension began in 2014, fossilized remains have routinely turned up from creatures that roamed the grasslands and forests that covered the region during the last Ice Age, about 10,000 years ago.
They include a partial rabbit jaw, mastodon tooth, camel foreleg, bison vertebrae, and a tooth and ankle bone from a horse.

But the discovery that still makes Leger shake her head in disbelief came about a year ago, shortly after construction began on the project's second phase. She was at home getting ready for bed when a call came in from one of her monitors.
"It looks big," he told her.
The next morning, Leger knelt at the site and recognized what appeared to be a partial elephant skull.

It turned out to be much more. After 15 hours of painstaking excavation, the team uncovered an intact skull of a juvenile mammoth.
"It's an absolute dream come true for me," said Leger, who spent the previous decade at a South Dakota mammoth site with no discoveries even close to the size of the one in Los Angeles. "It's the one fossil you always want to find in your career."

California's stringent environmental laws require scientists to be on hand at certain construction sites.