HEPATOPHYTES FROM THE EARLY CRETACEOUS OF ALEXANDER-ISLAND, ANTARCTICA - SYSTEMATICS AND PALEOECOLOGY

Hepatophytes from an important component of the Lower Cretaceous (late Albian) flora of Alexander Island, Antarctica. The liverworts Marchan tites rosulatus sp, nov., Thallites bicostatus sp, nov., and Thallites sp, colonized freshly deposited river sands and muds, forming distinc t carpets that probably served to bind the sediment and allow the succ ession of other plant groups. Within established plant communities, M. pinnatus sp. nov. and M. taenioides sp. nov. formed a ground layer be neath an overstory of the ferns Alamatus bifarius and Aculea aciculari s. Swampy communities with an overstory oi the conifers Podozamites an d Elatocladus contained a variety of thalloid (M. undulatus sp. nov., Hepaticites minutus sp. nov.) and leafy liverworts (Hepaticites spp.). The distribution of in situ liverworts, and a clear association of ta xa with a variety of foliage types, indicated that the hepatophytes oc cupied a wide range of ecological niches during the Cretaceous. The hi gh within-flora diversity and relative abundance of individual hepatic s appeared to be a special feature of high-latitude vegetation during the Cretaceous.