Story highlights The fact that crews are finding fossils isn't surprising

Ice Age fossils from mammoths to ancient camels have emerged

(CNN) The crews working on expanding Los Angeles' subway line keep running into a roadblock: 10,000-year-old fossils.

They just keep popping up. Mammoths, mastodons, bison.

Dave Sotero, the spokesman for the city's Metropolitan Transit Authority's (MTA), summed it up best:

"The prehistoric past is leading the subway future."

A mammoth tusk discovered

The MTA's Purple Line extension project is meant, according to its website , to be a "high-capacity, high-speed, dependable alternative" for commuters to and from places like Beverly Hills.

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