At Explorit, dig into the world of fossils

Fossils are old. Bacteria fossils go back 3.5 billion years. Even the comparatively recent remains of saber-toothed cats from the La Brea tar pits in Los Angeles go back 40,000 years. Human understanding of the true nature of fossils, however, only goes back a few centuries.

Leonardo da Vinci recognized the fossilized clamshells he found atop mountains in northern Italy as the preserved remains of once-living animals. However, most other scholars during da Vinci's time thought fossils grew inside the Earth inorganically, like crystals.

That little-known fact and many more will be shared during Saturday’s “Fossil Fun” Family Exploration program at Explorit Science Center, 2801 Second St. From 1-4 p.m., visitors will get to participate in a mock excavation, look at some real fossils and make a plaster fossil cast to take home. Visitors also will see pictures from real fossil hunting expeditions as well as learn about some places to find fossils in California. (The program is free with museum admission.)

You could say that Explorit visitors will become – at least for the afternoon – paleontologists, or scientists who study fossils. Paleontology began around 1666 when the Danish scientist Nicolas Steno discovered that the curious "tongue stones" found around Europe were actually shark teeth. Around the same time, the English scientist Robert Hooke used his microscope to examine petrified wood and concluded that his fossils were once living organisms.

Just 11 years after Steno uncovered the secret of the "tongue stones," the first dinosaur fossils were found in England, although the word "dinosaur" wasn't invented until 1842. In 1865, Charles Darwin's insights into the evolutionary history of life gave scientists a new way of looking at fossils and new reason to study them.

Paleontology has come along way since Steno and even since Darwin. A modern-day paleontologist might use a CT-scan to peer inside an interesting fossil instead of a microscope. Still, every year new discoveries are made that make scientists reconsider long-held assumptions about the history of life.

Just this year, paleontologists have described a new fish-like organism (Tiktaalik) that shares some features with early amphibians; a large mammal-like animal (Castorcauda) that lived when most mammals were the size of a shrew; an ancient water bird (Gansus); and a whole cast of unusual new dinosaurs (Mapusaurus, Erketu and Guanlong).
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Explorit Science Center is open at its new site, 2801 Second St., Davis. Through Dec. 10, you can visit the exhibition “Holes: An Opening Into the Sciences.” Public hours are Saturday and Sunday from 11 a.m. to 4:30 p.m. and Tuesday through Friday from 2 to 4:30 p.m. For more information: www.explorit.org or (530) 756-0191.