KESTER, PAUL R. Department of Geological Sciences, University of Washington, Seattle, WA 98195. - Tracking the radiation and regional extinctions of the genus Cunninghamia (Taxodiaceae).
The genus Cunninghamia, family Taxodiaceae, is now
distributed in the mixed mesophytic forests of southeastern China and
the mixed coniferous-deciduous hardwood forests of Taiwan. Currently,
three species of Cunninghamia are recognized: C.
konishii, native to the mountainous northern region of Taiwan, and
C. lanceolata and C. unicanaliculata, native to
southeastern China. Despite the limited number of species and their
restricted geographical distribution, Cunninghamia has an
extensive paleobotanical record. Earliest fossil records of
Cunninghamia are found in the Yuanbaoshan Formation, of Inner
Mongolia. The age is assigned to middle early Cretaceous
(Hauterivian-Barremian). By the middle Eocene,Cunninghamia was
distributed in both western North America and western Europe. Early
Paleogene fossils from the Eureka Sound Group, Ellesmere and Axel
Heiberg Islands in the Canadian Arctic (paleolatitudes of 75-80° N)
indicates migration via both the Bering and the North Atlantic Land
Bridges by the late Paleocene (Thanetian). Cunninghamia became
extinct in both North America and Europe by the end of the Miocene.
The present distribution of the genus is limited to regions of mean
annual temperature (MAT) of 15° to 19° C and mean annual precipitation
(MAP) exceeding 1500 mm. Its limited distribution is a result of
continual global cooling since the Eocene thermal maximum.
Key words: biogeography, Cunninghamia, Taxodiaceae