SAN DIEGO -- The first ancient whale bones ever found in San Diego County were unearthed this month at an East Village construction site, beneath the remains of a Columbian mammoth that were found earlier, it was announced Thursday.

The bones of a baleen whale from the Pleistocene Era were discovered Wednesday afternoon at 11th and Island avenues at a construction site for the new Thomas Jefferson School of Law campus, the school's Chris Saunders said.

The bones are from the first marine mammal to be dug up in San Diego County from that period, which ranged from 10,000 to 1.8 million years ago, according to Tom Demere of the San Diego Museum of Natural History.

Demere believes the whale was more than 40 feet long based on the size of its ribs.

Saunders said several ribs, a piece of skull and part of the lower jaw have been found.

The whale bones were discovered 10 feet below where an eight-foot mammoth tusk was uncovered Feb. 4 by a backhoe operator. Scientists eventually dug out the other tusk, a skull and other bones belonging to the mammoth, which roamed the earth about 500,000 years ago.

The law school, currently based in Old Town, is building a new $68.5 million, eight-story building that's scheduled to be open in time for the 2010- 11 school year.