Leafcutter Bee Fossils Provide Deeper Understanding of Ice Age Environment

Ice Age

A recent analysis of a new leafcutter bee fossil has helped provide a deeper understanding of the environmental conditions during the last Ice Age. These fossils were extracted from the famous Rancho La Brea Tar Pits, Southern California. Some even believe that the analysis would help better comprehend what life was like in the glacial age all those years ago.

The last glacial age, most popularly known as the Ice Age, was the most recent glacial period that occurred approximately 110,000 to 12,000 years ago. From the perspective of human archaeology, this falls somewhere in the Paleolithic and Mesolithic periods. The La Brea Tar Pits are a group of pits in Los Angeles and are home to the preserved fossils of thousands of prehistoric animals that were unfortunate enough to get trapped in them.

The La Brea Tar Pits are also rich with fossils of animals that thrived during the Ice Age. The Pits however are most commonly known for the collection of woolly mammoth and saber-toothed cat fossils. Other abundant fossils present in the pits include a number of insect collections. Among these collections are a rare breed of leaf cutter bees along with their nests that were first discovered in the 1970s.

These nests were later examined and were found to contain pupae (an insect in the inactive form between larva and adult). These examinations was led by Anna R. Holden of the Natural History Museum, Los Angeles County and her colleagues. The study was also conducted in the presence of bee specialists from Utah University Dr. Terry Griswold and John B. Koch. Other major contributors included paleontologist Dr. Diane M. Erwin and Justin Hall. These studies exemplify how bee fossils provide a deeper understanding of the prevailing environmental condition during the Ice Age.

The insect nests were first micro CT scanned by Hall to recreate images of the insect cells and bees. It was necessary to scan the cells so that Holden and her colleagues could accurately determine if each nest contained a pupae that was completely intact. The team then examined the construction of the nest with the physical features of the bees and used environmental niche modeling to match the Ice Age specimens to Megachile gentilis. As Megechile gentilis is still alive today, Holden linked the records of its climate range to the late Ice Age climatic conditions near the pits.

This suggested that the Megachile gentilis lived in a climate that was moderately moist which occurred at a lower elevation during the late Pleistocene. The presence of leaf cells in the nest structures indicate a nearby habitat filled with woods or that which contained a river or stream.

Scientists have so far excavated at least 5 million fossils representing more than 600 species of plants and animals from the pits. These numbers indicate that Los Angeles was abundantly populated with wildlife more than 50,000 years ago. Holden said that since this was the fossil of a rare life stage, it was an exceptional find in itself.

This however was just the tip of the iceberg. Insects offer a vivid portrait of the conditions that persisted in the prehistoric world and there are literally thousands more to study from. Further dwelling into the world of these insects would help create a concrete description of what life was like during the Ice Ages.

By Hammad Ali


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