Biogeography and Endemism
Solifuges occur on all continents except Australia and Antarctica. They are also absent from Madagascar and New Zealand. Four of the twelve recognized families are represented in the Western Hemisphere, where members of the families Ammotrechidae, Eremobatidae, and Mummuciidae exclusively occur. The families Ceromidae, Galeodidae, Gylippidae, Hexisopodidae, Karschiidae, Melanoblossiidae, Rhagodidae and Solpugidae are restricted to the Eastern Hemisphere. One family, the Daesiidae, is present in the southern part of both hemispheres.
Current research projects (see under Phylogeny) are revealing more information about family level relationships and about how underlying evolutionary and biogeographic processes have influenced family and species distributions. What we do suspect regarding the biogeography of these desert-adapted arachnids is that the families and species diversified as desert habitats appeared on the planet. Solifuges, in fact, could be an ideal, but underexplored taxonomic group that could help inform us about the evolution of desert biotas. A study by Cushing et al. (2015) revealed that the North American family Eremobatidae most likely arose in the Cenozoic and diversified in the Oligocene as steppe and semidesert habitats began to replace forests and savannas in western North America.