CU Museum: Exhibits: Stone Lace: Museum Research: Using Fossil Insects to Determine Ancient Climates

Research by Amy P. Moe, Invertebrate Paleontology Collection Manager and Recent Graduate of Museum and Field Studies Program, CU Museum


UCM specimen, Family Bibionidae, Common Name: March Fly. Unknown Collector. Florissant Formation

Despite the fact that many researchers have successfully used relatively recent fossil insects to determine Quaternary (the last 1.8 million years of life) climates, older insect fossils have not been used for this purpose. Recent graduate and Invertebrate Paleontology Collection Manager, Amy Moe, decided to examine the accuracy with which older insect fossils can be used to describe ancient climates.

Using fossil flies (Diptera) from the Florissant Formation (Eocene) of Colorado, Ms. Moe used the Mutual Climatic Range (MCR) method of determining paleo (or ancient) climate, a method which compares the geographic ranges of insects from a specific location to that insect's known climatic tolerances (temperature minimums, maximums, and averages). The climactic tolerances of each insect found at a particular site are plotted on a graph, and the range where all the insects overlap represents the overall climate range for the area at that time.


	UCM specimen, Family Tipulidae, Common Name: Crane Fly. Collected by TDA Cockerell. Florissant Formation

A database of the climate ranges of modern flies was compiled and the MCR method was performed on all fossil Diptera from Florissant that have living representatives. The estimate of the climate from these analyses were then compared to estimates obtained from previous studies of fossil plants from Florissant.

Ms. Moe discovered that using a MCR approach with fossil flies can provide an accurate estimate of paleoclimate for older fossil groupings. The climate estimate for the Florissant area in the Eocene era was 12-14°C, which is well within the range of estimates for Florissant that scientists derived from plant fossils. The temperature indicated by the climate estimate indicates a warm-temperate to temperate environment. This research ultimately demonstrated that fossil insect assemblages can provide an important resource of data for estimating ancient climates.