Crews digging a tunnel for a new Los Angeles train line have found the remains of an ancient giant sloth.

The Metropolitan Transportation Authority says a fossilized hip joint was discovered on May 16 in a layer of sandy clay 16 feet below a major thoroughfare where the new rail line is being built.

The bone is from a Harlan's ground sloth, a mammal that roamed the Los Angeles basin 11,000 years ago. The sloths grew up to 10 feet in length and weighed up to 1,500 pounds.

A bone from an extinct bison also was found.

Large mammals flourished in the LA area thousands of years ago. Excavations for train projects have turned up bison and camel bones as well as mastodon teeth and tusk fragments.