The first fossil rove beetle from the middle Eocene Kishenehn Formation (North America) provides evidence for ancient Eocene relicts within the hyperdiverse Staphylinini (Coleoptera: Staphylinidae: Staphylininae)

From 55 to 37 million years ago, the Earth underwent a major reorganization in the pattern of its climate. Earth changed from a warm, equable and ice free world to one with frozen poles and distinct bands of climate regions, including temperate ecosystems. Studying how insects responded to past climate change may provide insight into future changes under current climate change. Fossils from this period provide direct evidence of these changes by taking a snapshot of ecosystems long ago. In this study, the researchers report and describe the first fossil rove beetle from the 46 million year old Kishenehn deposit in Montana, USA. To understand the significance of this fossil to past climate change, researchers needed to identify it and better understand the relationships between its potential living relatives. Non-fossil specimens from the world’s museum collections, including AAFC, were studied by researchers from Canada, Austria and the United States to provide the needed context. The fossil was identified as a belonging to a group of beetles that today mostly occur in the subtropics and tropics, and whose closest relatives today occur in Central America and the Caribbean. This fossil provides direct evidence for the ancient age of these beetles and shows that the Kishenehn site in Montana was much warmer than it is today.