Today鈥檚 Wow听Bibionids听(March Flies)听take us back to the听Eocene,听56听to听34听million years ago.听Fossilized听Bibionids听like these听are very common in fossil insect deposits from Florissant and the Green River Formation in Colorado. They are often found together in groups of multiple specimens in Green River deposits (sometimes more than 20听together). These specimens were collected in the early 2000s from the Green River Formation by Mr. David Kohls.听Green River Formation听outcrops听can be found听at the intersection of Colorado, Wyoming and Utah. It is formed of sediments from an ancient group of intermountain lakes. A very cool feature is that seasonal sediment varied in color, so layers from single years can be studied!听听
Today鈥檚 Bibionids are known to swarm in clusters during the spring and the adults of the species are herbivores and pollinators.听Some species are听known as 鈥渓ove bugs鈥� for their conspicuous copula behavior (staying attached for long periods, even in flight),听some听species听do not eat听(too busy mating?), instead surviving on food ingested听during听their听larval听stage.听听
In the early 1900s, CU Curator TDA听Cockerell听collected and described some of the first known bibionids from Florissant听(Florissant and Green River Formation are two of the best sites in the world for Eocene fossils鈥攂oth right here in Colorado). You can听, from 1909, for free from the Biodiversity Heritage Library if you would like to see what a scientific species description looks like from that era. They were much shorter and contained few, if any photographs, but sometimes a line drawing was included. Today we are able to include much more lengthy descriptions of morphology and lots of high-resolution digital images that clearly show the听identifying听morphology.听This technology along with the incredible preservation of some Green River Formation insect fossils,听allows听identification to family and subfamily听and听sometimes show color patterns, wing venation, and sex-related characteristics.听