Collaborative Research: Chronology and Ecology of Late Pleistocene Megafauna at Rancho La Brea

Los Angeles County Museum Of Natural History Foundation, Los Angeles CA

Investigators

Abstract

The Rancho La Brea tar pits of Los Angeles, California contain thousands of bones from large mammals --dire wolves, sabertooth cats, coyotes, extinct bison, horses, and others-- trapped in sticky surface oil deposits during the last Ice Age. This unparalleled fossil assemblage allows rigorous studies of extinct mammal biology, especially of carnivores which are rare at most fossil sites. The La Brea fossils span a critical time in Earth's history (approximately 50,000 years ago to the present) that includes major events such as the end of the last Ice Age, the arrival of humans in North America, and an extinction that killed two thirds of the large mammals on the continent. This unique deposit will be used to investigate relationships between major environmental changes and evolutionary variation (size, diet, etc.) in large mammals, information that is critical for promoting the survival of wildlife today. The project involves significant community outreach in the greater Los Angeles area through the Tar Pits Museum and will create educational content that will be available online for high school teachers across the country. The major impediment to system-level study at Rancho La Brea is a paucity of radiocarbon dates and the resulting inability to correlate biotic change with time. This project will intensively radiocarbon date samples from multiple pits spanning the last 50,000 years to establish the first detailed chronology for the entrapment of four extinct species of large mammals, and one extant species. It will involve the collection and compilation of census data for these species to track changes in total abundance and diversity, as well as data on morphological and dietary changes. A well-resolved chronology will allow these data on evolutionary changes in mammals and the Pleistocene megafaunal extinctions to be linked to existing records of major paleo-environmental changes. This work will have broad implications for our understanding of extinctions, survival, environmental variables, and humans on mammalian ecology, which is directly relevant to modern conservation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.