Hepatophytes from the Early Cretaceous of Alexander Island, Antarctica: systematics and paleoecology
Hepatophytes form an important component of the Lower Cretaceous (late Albian) flora of Alexander Island, Antarctica. The liverworts Marchantites rosulatus sp. nov., Thallites bicostatus sp. nov., and Thallites sp. colonized freshly deposited river sands and muds, forming distinct carpets that probably served to bind the sediment and allow the succession of other plant groups. Within established plant communities, M. pinnatus sp. nov. and M. taenioides sp. nov. formed a ground layer beneath an overstory of the ferns Alamatus bifarius and Aculea acicularis. Swampy communities with an overstory of the conifers Podozamites and 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 taxa with a variety of foliage types, indicated that the hepatophytes occupied a wide range of ecological niches during the Cretaceous. The high within-flora diversity and relative abundance of individual hepatics appeared to be a special feature of high-latitude vegetation during the Cretaceous.