Oct. 24-26, 2009, Yingjie Overseas Exchange Center, Peking University, Beijing, China中文版

Early Cretaceous flowers and the Darwin mystery

Else Marie Friis1, Kaj Raunsgaard Pedersen2 and Peter R. Crane3

1 Department of Palaeobotany, Swedish Museum of Natural History, Box 50007, SE-10405 Stockholm, Sweden,
2 Department of Geology, University of Aarhus, Universitetsparken, DK-8000 Århus C, Denmark,
3 School of Forestry & Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT 06511, USA,

Abstract

The appearance and dramatic radiation of angiosperm in the Cretaceous was one of the major biotic upheavals in the history of life. This late and apparent sudden arrival of angiosperms, almost 300 million years after the first land plants started to colonize Earth, was a puzzle to Darwin and his contemporaries. Darwin himself famously labeled the Cretaceous appearance of angiosperms an “abominable mystery”. Since Darwin’s time much more has been learnt about the pattern of angiosperm diversification and some aspects of his “mystery” now seem much less problematic. The discovery and study of fossil flowers and other reproductive organs from the Cretaceous has played an important role in recent progress and has provided unexpected insights into the early phases of angiosperm diversification. The new picture that continues to emerge indicates that angiosperms were diverse already by the Late Barremian-Early Aptian, albeit represented by extinct lineages and a limited selection of extant lineages related particularly to ANITA-grade angiosperms, Chloranthaceae and basal monocots. This phylogenetic diversity is strikingly different from the much more modern appearance that characterizes Late Cretaceous and younger floras. Early in the diversification the occurrence of angiosperms was probably patchy, and the earliest angiosperms appear mainly to have been insect pollinated, herbaceous or shrubby, plants of low stature and low pollen production. Together with ferns they may have formed the ground cover in open areas or the understory in open-forests dominated by xeromorphic conifers and plants related to Bennettitales, Erdtmanithecales and Gnetales. Systematic assignments, together with the general morphology of the vegetative remains of early angiosperms, also suggest that the aquatic habit was established at a very early stage in angiosperm history.

Else Marie Friis

Department of Palaeobotany, Swedish Museum of Natural History, Sweden

Biography

Else Marie Friis is borne in Denmark 1947. She studied geology and botany at the University of Aarhus, Denmark, and has during her entire research career focused on questions related to the geological history of flowering plants. Since about 1980 her research has concentrated mainly on Cretaceous flowers and other reproductive structures to understand the origin and early diversification of angiosperms in a geological and biological perspective with a special focus on the flower and reproductive biology of Cretaceous angiosperms. The research is primarily based on the study of extensive collections of exquisitely preserved fossil flowers and other angiosperm reproductive organs from Cretaceous strata and is carried out in collaboration with her long term collaborators Kaj Raunsgaard Pedersen and Peter R Crane, as well as many other colleagues around the world. Since 1987 she is professor of palaeobotany and head of department at the Swedish Museum of Natural History, Stockholm. She has served the research community as member of several research councils, foundations, and committees, and as editor or co-editor for a number of scientific journals. She is a member of the Danish, Swedish, Norwegian and Chinese Academy of Sciences, and the Royal Physiographic Society, Sweden.