A new damselfy from the Lower Eocene Green River Formation (Odonata, Dysagrionidae)

Abstract

The Eocene Green River Formation in the USA is well known as a Konservat-Lagerstätte, and has yielded an enormous number of beautifully preserved fossil insects from the Parachute Creek Member of Lake Uinta in Colorado and Utah, USA (Grande, 1984) where insects dominate the fauna. In Fossil Lake deposits, fish dominate the fauna with insects a minor component. This formation spans a 5-myr-long period between ca. 53.5 and 48.5 Ma (Smith et al., 2003) in three distinct basins containing lacustrine sediments. Many of these fossils are in an exquisite state of preservation, occasionally even with soft tissues and colour patterns preserved (e.g., Bechly et al., 2020). As this entomofauna is one of the most diverse for the Early Eocene, increasing its knowledge is crucial for the understanding of the evolution of the insects at that time. This is especially the case for the Odonata, a clade that remains poorly known for the Paleocene and early Eocene (Nel & Jouault, 2022). Bechly et al. (2020) provided a first revision of the damselflies from the Green River Formation, but continuing excavation produces new specimens. The specimen described herein was recently discovered while excavating fossil fish in the Fossil Lake deposits of the Green River Formation in southwest Wyoming. This new species of Zygoptera from the Fossil Lake deposits further demonstrates its impressive diversity of Odonata.