ORIGINAL PAPER Historical biogeography of the genus Chamaecyparis (Cupressaceae, Coniferales) based on its fossil record (Christopher) Yu-Sheng Liu & Barbara A. R. Mohr & James F. Basinger Received: 16 July 2009 / Revised: 11 August 2009 / Accepted: 26 August 2009 / Published online: 9 October 2009 # Senckenberg, Gesellschaft für Naturforschung and Springer 2009 Abstract The megafossil record of Chamaecyparis (Cupres- saceae) 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. Keywords Chamaecyparis . Disjunction distribution . Dispersal . Fossil record . Historical biogeography . Land bridge Introduction For nearly two centuries, the distinctive disjunction of taxa between eastern Asia and eastern North America has remained a classic phytogeographical phenomenon (Gray 1846; Mai 1995; Wen 1999, 2001). Recently, however, comparative analyses of molecular sequences from nuclear, mitochondrion, and chloroplast DNA and RNA have contributed not only to our understanding of phylogenetic relationships, but also to that of biogeographic patterns of dispersal (Manos and Donoghue 2001), adding to an already substantial body of data based on the more traditional fields of botany and paleobotany. In this context, Chamaecyparis (Cupressaceae) is con- sidered to have a typical disjunct distribution (Li et al. 2003; Wang et al. 2003). Two independent studies on the historical biogeography of all extant Chamaecyparis spe- cies, both based on the analysis of DNA, have been recently published (Li et al. 2003; Wang et al. 2003), with each proposing explanations for the intercontinental dis- junction of Chamaecyparis. The two studies share one common aspect: Europe, due to the lack of any living Chamaecyparis species, was completely excluded from the biogeographic analyses. Nevertheless, in the paleobotanical literature it has been well documented that Europe, among the three major landmasses of the Northern Hemisphere, played a crucial role in past plant migrations, including Chamaecyparis (Kotyk et al. 2003; Mai 2004). It is admittedly difficult for phylogeographers to include in their analysis a region from which taxa are This is PCSP/PPCP publication number 03509. (. Y.-S. Liu (*) Department of Biological Sciences, East Tennessee State University, Box 70703, Johnson City, TN 37614-1710, USA e-mail: liuc@etsu.edu B. A. R. Mohr Institute of Palaeontology, Museum of Natural History, Humboldt University of Berlin, Invalidenstrasse 43, 10115 Berlin, Germany J. F. Basinger Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2 (C.) Y.-S. Liu (*) Palaeobio Palaeoenv (2009) 89:203–209 DOI 10.1007/s12549-009-0010-8