The ice age La Brea Tar Pits in Los Angeles, California, USA is among the world’s most important fossil sites because it is one of the only places on earth that preserves an entire past ecosystem, allowing scientists an unprecedented opportunity to understand how long-term processes like climate change and extinction impact ecological communities. However, to date, the vast majority of research at this locality has focused on the large, extinct mammals preserved there, ignoring the small animals and plants which are both more ecologically informative and key to ecosystem function. For this project, investigators took advantage of a newly discovered set of deposits at La Brea ("Project 23"), a collection of tar pits excavated using modern techniques that recover the smaller fossils (i.e., tiny mouse teeth or juniper seeds) that were missing from many of the earlier excavations at this site. Team members, including postdoctoral scholars, graduate students and undergraduates from UC Merced, the University of Maine, and the La Brea Tar Pits and Museum, as well as Museum staff and volunteers, sorted and identified tens of thousands of small mammal and plant specimens, filling in the broader picture of the LA area ecosystem during the time of sabertoothed cats and giant sloths. This project extended the chronology of Rancho La Brea back to >55,000 years ago, developed the first comprehensive catalog of plants that grew in the LA Basin before the Last Glacial Maximum, completed a comprehensive list of small mammal taxa found at the Project 23 deposits, and developed a new generation of food web models focused on understanding plant-herbivore interactions and predicting community structure. Although La Brea Tar Pits is famous for now-extinct mammals like sabertoothed cats, dire wolves, and mammoths, our research demonstrated that the small mammal community in the LA Basin remained relatively stable from before the Last Glacial Maximum through today.  

A key component of this project was a classroom-based microfossil sorting activity that was run in schools throughout the LA region, engaging hundreds of students in sorting and identifying plant and small vertebrate fossils from Project 23 deposit matrix, and supporting lesson plans on paleontology, global change, and scientific methodology.  The workflows and partnerships developed in this project will be used in the Tar Pits' ongoing education and outreach efforts, and will provide a model for other institutions interested in engaging students with fossil sorting and identification experiences.  Finally, details of this research project have been incorporated into interpretation at the Tar Pits Museum, which receives hundreds of thousands of visitors per year. 

Last Modified: 12/30/2021
Modified by: Luis M Chiappe