Microfossils (actual size)

An enlarged (x2) view of microfossils. One of the most incredible aspects of Rancho La Brea is the variety of its fossil record. The asphalt has not only preserved animal bones, but also plants, insects, and other smaller-sized specimens that are too small to be seen with the naked eye. These small objects are called microfossils. At Rancho La Brea, microfossils include freshwater shells and small animal bones that are usually identified with the aid of a magnifying glass or a microscope. These small fossils give scientists the most complete look at the environment of the Los Angeles area 40,000 years ago. Foot Note! Although microfossils can be very small and difficult to identify, the trained eye can easily identify deer mouse teeth from those of other rodents of the same size!

The Los Angeles Basin 25,000 years ago

The reconstruction of the Pleistocene climate begins with microfossils. For instance, plant material is the best indicator of weather. The fossil record includes wood, leaves, cones, and seeds. The presence of chaparral-type plant life along with coastal redwood and other canyon-dwelling trees suggests that the Pleistocene climate of Los Angeles was not drastically different from the present day. In fact, the best available evidence points to a climate similar to coastal Monterey or San Francisco, California. This climate is slightly more humid and cooler than one typically associated with the present day environment of the Los Angeles area. It is a common misconception that all Ice Age climates included glaciers and ice sheets covering the landscape. This type of landscape was far away from Rancho La Brea and was nearest in the Sierra Nevada Mountains.

La Brea Flora and Fauna