Depending on the time of day or year, strong and healthy animals may have managed to escape, but others would have been held fast until they died of exhaustion, or fell prey to passing predators. Under the right conditions, a single mired large herbivore would attract the attention of a dozen or more hungry carnivorous birds and mammals, some of which would find themselves trapped, providing more food for other carnivores. This cycle repeated during the 30,000 years that fossils were accumulating at Rancho La Brea. The remains of only one human have ever been found at Rancho La Brea. Seventeen bones, including the skull and pelvis, were recovered from Pit 10 in 1914, along with a few artifacts and the partial skeleton of a domestic dog.
Evidence indicates the woman was the victim of violent blow to the head.
Scattered artifacts of human origin have also been found. Evidence indicates that four plant associations occurred in the region. Coastal sage scrub broken with groves of pines and cypress grew in the immediate vicinity of the asphalt seeps. Chaparral, with some pine and juniper scattered within, covered the slopes of the local mountains. Stream courses crossing the plain supported a riparian association that included sycamore, walnut and numerous herbs.