Biogeography of Lower Carboniferous crinoids

Abstract The stratigraphic are ranges of all known crinoid genera of Mississippian and Lower Carboniferous age in western Europe and North America compared. Camerate crinoid distribution was published in 1987 (Lane and Sevastopulo). Inadunate and flexible crinoid ranges are presented here. A total of 197 genera are involved, 157 in North America and 93 in Europe, with 53 joint occurrences. Conspicuous endemism occurs at both the familial and generic levels in both Europe and North America. In early Mississippian time camerate crinoid genera are especially endemic in North America and many become extinct. In later Mississippian time many poteriocrinoid and flexible crinoid genera and some families are confined to either North America or Europe. Both environmental and physical barriers contributed to isolation and endemism. Genera tend to originate first, and become extinct first, at about equal rates in North America and in Europe. European genera tend to be somewhat longer ranging than North American genera, perhaps due to differences in breadth of definition on the two continents. Primitive groups like disparid and cyathocrinoid inadunates range up from the Late Devonian. Advanced poteriocrinoid inadunates commonly range up into younger Pennsylvanian-Upper Carboniferous rocks. New families originated in both North America and western Europe with about equal frequency. New Japanese occurrences of Pennsylvanian inadunates and the age relations of Permian Timor crinoids are discussed briefly.