A Krefft's glider (Petaurus notatus) in remnant rainforest on the Atherton Tablelands in Queensland, Australia. These and other gliding vertebrates are well adapted to tall forests, relying on tree hollows for nesting and insects, gum, sap, pollen and nectar for foraging. In our study we found that global species richness of gliding vertebrates is strongly linked to tree height and density. Our results support long-debated hypotheses stating that gliding in vertebrates evolved globally in tall forests as energy-efficient locomotion between trees. Photo by Benjamin Wagner.