La Brea Bee fossils

The analysis was conducted on leafcutter bee fossils extracted from the La Brea tar pits.
Image: Holden AR et. al / Plos One

The La Brea Tar Pits, known as the world’s richest and most important Ice Age fossil and located in Los Angeles, recently saw growth to its vast insect collection. The location is most celebrated for its collection of saber-toothed cats and mammoths but with recent examination of fossil leafcutter bee nest cells, the attention has shifted to the locations insect collection. The examination, led by Anna R. Holden of the Natural History Museum of Los Angeles County and colleagues, exemplifies how fossil insects reveal new insights into the local habitat and prevailing climate at the Tar Pits toward the end of the last Ice Age.

The paper, entitled “Leafcutter Bee Nest and Pupae from the Rancho La Brea Tar Pits of Southern California: Implications for Understanding the Paleoenvironment of the Late Pleistocene,” will be published in the journal PLoS One on April 9, 2014. Holden conducted the study with bee specialists Jon B. Koch and Dr. Terry Griswold from Utah State University, paleobotanist Dr. Diane M. Erwin from the University of California Berkeley, and Justin Hall from NHM, who used micro CT scans to reconstruct images of the nest cells and bees.

Finding the intact bee pupae allowed the group to use environmental niche modeling to best match the ancient Ice Age specimens to Megachile gentilis, which still lives today. The identification of nest cell leaf fragments indicates a nearby wooded or habitat with a stream or river. Dating back to the beginning of the 20th century, scientists have unearthed more than 5 million fossils representing 600+ species of plants and animals from the tar pits — evidence that Los Angeles was densely populated by wildlife for more than 50,000 years. “This vast treasure trove of fossils is key to understanding the response of the wildlife and habitats of Southern California to global cooling and warming at the end of the Ice Age,” said Dr. John Harris, Chief Curator of the Page Museum. “It affords an evolutionary perspective to ongoing climate change.”

Cover Image: Shutterstock