Yale Undergraduate Uncovers New Eocene Sawfly Species in Colorado Quarry

A junior at Yale College has identified a previously unknown species of sawfly after conducting fieldwork in a remote quarry in western Colorado, adding a fresh entry to the fossil record of the ancient Green River Formation.

The quarry, situated within the sedimentary layers of the Green River Formation, reveals rock strata that date back roughly 50 million years to the early Eocene epoch. The formation is renowned for its exceptionally preserved fossils, which have long served as a window into the flora and fauna that thrived after the Paleocene‑Eocene Thermal Maximum.

Sawflies belong to the order Hymenoptera, a group that also includes wasps, bees, and ants. The newly described species displays a unique combination of wing venation patterns and body morphology that sets it apart from known Eocene sawfly taxa, prompting researchers to assign it to a distinct genus.

Leah Mock, the Yale student who led the excavation, collected the specimens using standard paleontological techniques, carefully extracting the delicate insect remains from the fine-grained limestone. The material was later examined by specialists in paleoentomology, who confirmed the diagnostic features that warranted the designation of a new species.

The discovery sheds light on the diversity of insect life during a period of warm global temperatures and expanding forested habitats. By expanding the known range of sawfly lineages, the find helps scientists refine models of insect evolution and biogeography in the early Cenozoic.

Experts familiar with the Green River Formation have noted that each new insect species adds nuance to the reconstruction of ancient ecosystems, offering clues about plant‑insect interactions, climate conditions, and the evolutionary pressures of the time.

Further analysis of the specimens, including detailed imaging and comparative studies with other Eocene insects, is planned. The research underscores the value of continued field investigations in well-studied yet still revealing fossil sites, and highlights the contributions that undergraduate researchers can make to paleontological science.