Boning Up on Local History

A set of Megalodon jaws, gaping 5 feet wide and bristling with rows of 6-inch-long teeth, is crowned with a sign that asks, “What Is a Fossil?”

Here at the Old Courthouse Museum in Santa Ana, the answer is not necessarily “dinosaur.” Fossils found in Orange County are much more likely to be something fishy, according to the current exhibit, “Legacy of Stone: Fossils of the San Joaquin Hills Transportation Corridor.”

That’s because what is now Orange County was underwater for a large part of prehistory. Megalodon, a giant shark estimated to measure 45 feet long and weigh 10,000 pounds, swam in Orange County waters 5 million to 23 million years ago.

The exhibit showcases significant fossil finds uncovered from 1992 to 1996 during construction of the toll road that runs from San Juan Capistrano to Newport Beach. More than 40,000 fossils were unearthed, including the most complete baleen whale skeleton ever found, more than 30 other whales along with dolphins, seals and sea lions.

There’s a life-size photo of the baleen whale and a video of its removal, but the whale itself is at the Ralph B. Clark Interpretive Center in Buena Park. Actual fossils on display in Santa Ana include a huge tooth and pelvis from an imperial mammoth, which stood 13 feet tall, a tiny but significant opossum tooth, fossil whale material, shark’s teeth, the skull of a northern fur seal and fossil shrimp.

Interactive exhibits range from the simple--one piece of land slides up and down to illustrate fault movement--to the fun--children can unearth their own fossil finds in a sandbox dig. The computer savvy can surf the Paleo Web, and a two-part display uses sliding glass overlays to show what Orange County has looked like in the past. Other displays examine the science of paleontology and the tools of the trade and explain how fossilization happens.

The exhibit, mounted by the Transportation Corridor Agencies under an agreement with Orange County, is small but has earned rave reviews from teachers such as Judy d’Albert, who teaches science at Harbor Day School in Corona del Mar. She visited the exhibit when it opened in April, made up a work sheet and assigned her sixth-graders to tour the display.

“It’s marvelous, absolutely marvelous. It’s made them connect with the land,” D’Albert said.

Visitors learn that Orange County was once about 250 miles farther south, about where Ensenada is today. During another period, a Nile-size river drainage system flowed through the county. At still another time, the area was a cluster of islands.

And for those worried about the fate of the gnatcatcher, consider this: 90% of the species that have lived on Earth are extinct. Most species live 2.4 to 4 million years. Comfortingly, the exhibit points out that Homo sapiens--that’s us--have been around only about 26,000 years so far.

The museum, on the third floor of the old courthouse at 211 W. Santa Ana Blvd., is open from 9 a.m. to 5 p.m. Monday through Friday. The exhibit runs through Sept. 25. Admission is free. Teacher packets on paleontology and Orange County are offered through TCA public affairs, (714) 436-9800. The agency is compiling a mailing list of teachers interested in a planned September seminar. Guided tours can be scheduled through the courthouse museum curator, (714) 834-4691.