Subway fossils.

While expanding the subway system in Los Angeles, California, last year, construction workers accidentally plowed into a treasure trove of fossils. The remains of 15-million-year-old fish and 8,800-year-old logs are among the most recent finds.

Biologists and geologists often have trouble digging up the money for such an extensive exploration. But because the subway project is paid for by the city, scientists were invited along for a free field day!

Actually, these latest fossil finds aren't the first to appear in L.A.'s underground. Since subway excavations began in 1986, paleontologists (fossil researchers) have been keeping track of many fantastic finds -- and briefing construction workers on what to look for as they dig.

Usually dead plants and animals decay quickly. So a layer of sand or dirt must have covered the dead animals soon after they died. The quick burial protected the bones from scavengers and bacteria, so the specimens that created the "subway" fossils were preserved.

Construction worker Michael Guinther, an amateur fossil collector, has discovered a number of the fossils. While working the graveyard shift 45 to 80 feet below Hollywood Boulevard in 1994, he saw a glint of white through dirt flying from his tunnel-digging machine. After stopping his machine, he grabbed his lunch bag, dumped out the food, and filled it with what turned out to be bones of bison, mastodon, camel, and an extinct species of horse.

But some of the most exciting finds have been the fish fossils. "The fish researcher has practically been doing back handsprings, he's so excited," says paleontologist E. Bruce Lander. The earth beneath L.A. has relinquished the most extensive collection of ancient fish ever uncovered in this country.

Some of the remains of L.A.'s ancient inhabitants will soon be displayed at the Natural History Museum of Los Angeles County. Go for a visit and discover them yourself.