April 1 to June 25, 2000

Treasures of the Tar Pits

The era when saber-toothed cats and mastodons roamed Southern California is revealed in the exhibition Treasures of the Tar Pits, on view at the Oakland Museum of California.

The exhibition features selected fossil skeletons of animals and plants that lived between 40,000 and 8,000 years ago, recovered from one of the richest deposits of Ice Age fossils in the world, Rancho La Brea. Also included are audio-visual presentations, interactive materials and vivid graphic panels showing how the animals were trapped in the tar, how their fossils came to be preserved, and how they were later discovered, excavated and reconstructed.

This will be the last opportunity to see the traveling exhibition, which was organized and circulated by the Natural History Museum of Los Angeles County. After its run at the Oakland Museum of California, the exhibition returns to its permanent home in Los Angeles, ending a remarkable 11-1/2 year tour in the U.S., Canada and Taiwan.

The exhibition features the fully articulated and mounted fossil skeletons of a California saber-toothed cat (Smilodon californicus), two dire wolves (Canis dirus), an American lion (Felix atrox), a Harlan's ground sloth (Glossotherium harlani) and a coyote (Canis latrans). La Brea Woman, 9,000 years old and the only human fossil remains found in the deposits, is also on display. Fossilized plants and bones of smaller mammals and birds are used to illustrate the diversity of the habitat and the selective nature of extinction.

Tar pits are formed when fissures in the Earth's crust allow crude oil to seep to the surface. As the lighter portion of the oil evaporates, the heavy tar, or asphalt, is left behind in sticky pools that capture the animals that wander into them, often attracted by water collected on the surface. The exhibition includes a specially designed "traveling tar pit" that illustrates firsthand the sensation of being stuck in tar.

Graphics, artifacts and photographs explain the ways in which people have utilized the asphalt deposits from 10,000 years ago to the present. Included are the history of Rancho La Brea, the first inhabitants, the arrival of the Spanish, commercial exploitation of the asphalt, the first fossil discoveries, and the 85-year history of paleontological work that has gone on at the site. Photographs from the early 1900s to the present show how excavation techniques have developed into state-of-the-art curatorial and conservation processes.

Fossil finds from the La Brea site are unique in terms of the huge sample size, the diversity of plant and animal species found, and the completeness of their preservation. These features illustrate the diversity of Ice Age life in Southern California and give paleontologists all over the world a vast amount of original material to study and analyze. The extinct vertebrate species from Rancho La Brea have been used to define an interval of time called the Rancholabrean Land Mammal Age, representing the last 500,000 years of the Pleistocene epoch.

The exhibition illustrates the environmental changes that have taken place in California over the past 40,000 years. Many of the plants and animals found in La Brea are identical or almost identical to species that still live in the area—or that would be living in the area had Los Angeles not gotten in the way. But a number of the large animal species found at La Brea are no longer found in North America: native horses, camels, mammoths and mastodons, longhorned bison and saber-toothed cats.

Even within the last century, remarkable changes have taken place in La Brea. Around 1910, it was described as "the Salt Creek oilfields, 7 miles west of Los Angeles." Today, La Brea is in the center of downtown Los Angeles, but the pools and deposits of asphalt still remain.

Although today herbivores are much more abundant than carnivores, at La Brea about 90 percent of the mammal fossils are carnivores, and most of the bird fossils are predators or scavengers. This doesn't necessarily mean that there were fewer herbivores at that time. It might be explained by the fact that the occasional herbivore coming to drink the water that had collected on top of the tar pit became trapped, thus attracting carnivores and scavengers in the area, who then became trapped themselves.

Family Explorations! Family Fossil Day was presented on Saturday, June 24, 2000 from noon to 4 p.m. in conjunction with the exhibition. Families examined real fossils, found out how fossils are excavated and prepared for display in a museum, and tried their hand at a simulated fossil dig. The program was free with museum admission.

Treasures of the Tar Pits is presented at OMCA with the generous funding of the Oakland Museum Women's Board, Weeden Foundation, McKesson HBOC Foundation and The Morris Stulsaft Foundation.

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