Yale Undergraduate Finds Previously Unknown Eocene Sawfly in Colorado Quarry

A junior at Yale College has uncovered a hitherto unknown sawfly species while conducting fieldwork at a secluded quarry in western Colorado, thereby adding a new entry to the fossil record of the ancient Green River Formation.

The quarry lies within the sedimentary layers of the Green River Formation, whose rock strata are dated to roughly 50 million years ago, placing them in the early Eocene epoch. This formation is celebrated for its remarkably preserved fossils, which have long provided a window onto the plants and animals that flourished after the Paleocene‑Eocene Thermal Maximum.

Sawflies belong to the order Hymenoptera, the same group that includes wasps, bees and ants. The newly described species exhibits a distinctive mix of wing‑vein patterns and body shape that differentiates it from other known Eocene sawflies, leading researchers to assign it to a separate genus.

Leah Mock, the Yale student who directed the excavation, gathered the specimens using standard paleontological methods, painstakingly extracting the fragile insect fragments from the fine‑grained limestone. The material was subsequently examined by paleoentomology specialists, who verified the diagnostic traits that justify naming a new species.

The find illuminates the variety of insect life during a time of warm global temperatures and expanding forested habitats. By broadening the documented range of sawfly lineages, the discovery assists scientists in refining models of insect evolution and biogeography in the early Cenozoic.

Specialists familiar with the Green River Formation note that each newly identified insect adds nuance to reconstructions of ancient ecosystems, offering insights into plant‑insect interactions, climate conditions, and the evolutionary pressures of that era.

Planned next steps include detailed imaging and comparative studies of the specimens against other Eocene insects. The research highlights the importance of ongoing field work at well‑studied yet still revealing fossil sites, and showcases the significant contributions undergraduate researchers can make to paleontological science.