Historical biogeography of the genus Chamaecyparis (Cupressaceae, Coniferales) based on its fossil record

Abstract

The megafossil record of Chamaecyparis (Cupressaceae) in the Northern Hemisphere, especially that in Europe, is reviewed with the aim of gaining a better understanding of the biogeographic history of this genus and providing an explanation of the causes of eastern Asian and western and eastern North American intercontinental disjunction of extant members. The fossil data available favor the hypothesis that earlier members of Chamaecyparis were widely distributed in the mid to high latitudes of North America and Europe during the Paleogene and that they spread via the North Atlantic land bridges. During a period of successive global climatic coolings in the Neogene, the distribution of the genus was gradually restricted until Chamaecyparis ultimately disappeared from Europe in the Plio-Pleistocene. Eastern Asian Chamaecyparis most likely came from North America via Beringia during the Paleogene or migrated from Europe eastwards after the Oligocene, when the Turgai Strait retreated. Eastern North American Chamaecyparis appears to have originated either from northern high latitudes or western North America.