Scientists Scan Rare Leafcutter Bee Fossils Found in La Brea Tar Pits

Posted on April 12, 2014

Rare leafcutter bee fossils were excavated from the La Brea Tar Pits in 1970. The fossils have now been examined closely with a micro CT scan technique. The 23-43,000 year old fossil leafcutter bee nest cells contain pupae. New research, led by Anna R. Holden of the Natural History Museum of Los Angeles County (NHM) and colleagues, reveals new details about the local habitat and limate at the La Brea Tar Pits toward the end of the last Ice Age. The image above compares a modern leafcutter bee pupa in a nest cell to the leafcutter bee pupa fossil.

The researchers matched the ancient specimen to Megachile gentilis, a leafcutter bee species which still lives today. The researchers linked records of the bees restricted climatic range to late Ice Age environmental conditions at Rancho La Brea. The scientists say their findings indicate that M. gentilis lived in a moderately moist (mesic) environment that occurred at a lower elevation during the Late Pleistocene. The identification of nest cell leaf fragments, which were collected in close proximity to the nest site, indicates a nearby wooded habitat with a stream or river.

Holden says in a release, "Because this is a fossil of rare life-stage, it's an exceptional find in itself. But it's just the tip of the iceberg, we know that insects offer a vivid portrait of the prehistoric conditions of this area, and there are literally thousands more to study."

A research paper on the leafcutter bee fossils was published here in PLoS One.

INSECTS