The Cenozoic macrofossil record of the Cupressaceae in the Southern Hemisphere

Abstract

Cupressaceae macrofossils are difficult to identify in older sediments, but the extant southern genera begin their record in the Cretaceous (Athrotaxis) and become more diverse and extensive during the Cenozoic. Several extinct genera of Cupressaceae also occur in Cretaceous and Cenozoic sediments, especially in Australasia, and some Cretaceous fossils appear to be more closely related to extant Northern rather than South­ern Hemisphere genera. However, information about the history of the dry forest Cupressaceae is extremely limited due to a lack of fossilisation in such environments. The southern Cupressaceae, past and present, demonstrate an ability to compete effectively with angiosperms and have co-existed with them for tens of millions of years. In south-eastern Australia and New Zealand at least, the generic diversity and probably the geographic extent of the Cupressaceae has declined since the Early Oligocene. This decline was probably directly tied to climate change, with the Neogene changes in rainfall (in particular increasing seasonality and aridity) having a marked effect. However, in at least some genera (e.g. the dry-adapted Callitris in Australia) there appears to have been an increase in diversity following continental drying.