The La Brea Tar Pits’ formation dates to at least five million years ago, when what would become Los Angeles was still underwater and its only lifeforms were single-celled organisms. This plankton slowly decomposed into oil deposits that later broke through to the surface, the result of earthquakes along the San Andreas fault. This petroleum would evaporate, leaving behind swamps of thick pitch for animals to become trapped in. Herbivores would be attracted to the area’s flora and become trapped, which in turn would attract predators, who would get themselves.

This grizzly cycle would play itself out again and again, the tar pits enclosing every level of the Pleistocene food chain. However, some scientists believe that tar entrapment alone cannot account for the incredible amount of specimens found at La Brea. For example, the small Pit 36 measures 4 feet by 2 feet by 11 feet, but held six large carnivores, an improbably high number. One explanation for this discrepancy is that the remains at La Brea are not exclusively animals that became trapped, but were transported to the pits by flooding. Regardless, the La Brea Tar Pits’ specimens have been invaluable in understanding the Pleistocene’s lifeforms. 

The pits' asphalt was used by the indigenous Tongva and Chumash people to waterproof their boats, a sealant in building their houses, and many other uses including chewing gum. The tar pits were documented in 1769 by friar Juan Crespí during the Spanish colonization of California, who deduced they were the result of the area’s earthquakes. The land was also a part of Rancho La Brea, a Mexican land grant that eventually passed to surveyor Henry Hancock who developed the pits for commercial use. Bones that had been found in the pits to this point were assumed to be from non-extinct animals, with fossils confirmed only in 1875.

Serious excavation efforts at La Brea began in 1913 and still continue today. Over the past century, thousands of specimens have been found. Carnivorous predators are best represented, as their herbivorous prey are trapped deeper down in the pitch. Beyond the coyotes and dire wolves that are best represented in the pits, La Brea is also known for its well preserved Columbian mammoth specimens, among them the massive Zed, with tusks that stretch ten feet long. One set of human remains have been discovered at La Brea, a young woman with a fractured skull who was perhaps murdered and deposited in the tar pits.

In spite of its long use as a paleontological site, new findings are still made at La Brea, as was the case in 2007 with the discovery of a microbial community living in asphalt samples from the pits. Just as the megafauna discoveries allow scientists to assemble a picture of Pleistocene life, this bacteria shed light on how extremophile microbes are able to evolve and survive in a harsh petroleum environment. Even after a century of exploration, La Brea is still yielding up new information on lifeforms, both big and small.

Want to study the tar pits up close? Check out the La Brea specimen for an authentic piece of tar pit geologic material!

Crafted here at Mini Museum, this resin-infused specimen was created using material from a selection of mined La Brea Tar Pit material which contained the remains of coyotes, dung beetles, rabbits, and even a bald eagle. The piece is enclosed in an acrylic specimen jar and ships in one of our small, classic riker cases.

Looking for something truly unique? Check out this special showcase fossil matrix from the La Brea Tar Pits. This 6.00" piece of La Brea tar material which contains a variety of fossils including a Desert Cottontail rabbit, fox metatarsal, and assorted bird bones.

The proximity of these fossils likely indicate that the creatures were hunting each other when they were trapped within the tar. We only have one of these specialty showcase items, so don't miss your chance to add it to your collection!