Araucaria bract-scale complex and associated foliage from the early-middle Eocene of Antarctica and their implications for Gondwanan biogeography

Abstract

ABSTRACTThe early-middle Eocene Fossil Hill flora from King George Island in the Antarctic Peninsula regions is one of the most diverse Cenozoic plant assemblages in Antarctica. It represents a rich Nothofagus and conifer dominated vegetation. These plant fossils, especially conifers are of crucial importance for understanding the biogeographic history of the Gondwanan plants. Here we describe the first Araucaria bract-scale complex, A. fildesensis sp. nov., and associated foliage from the Fossil Hill flora and tentatively assigned them to the Section Eutacta, which is today restricted to Australasia, based on comparison with extant material. This study confirms that Araucaria species with small bract-scale complexes, small scale-like mature leaves and awl-shaped juvenile leaves like those of extant Section Eutacta, lived in Antarctica in the Eocene. These fossils provide potential evidence for the trans-Antarctic floristic changes of Araucaria species in the Section Eutacta between southern Australia and southern South America during the Eocene, when Antarctica was ice-free and forested.