DIVERSITY AND ECOLOGY OF PERMIAN FLORAS FROM ANTARCTICA.

DECOMBEIX, ANNE-LAURE; ESCAPA, IGNACIO; SCHWENDEMANN, ANDREW; SERBET, RUDOLPH; TAYLOR, EDITH L.; TAYLOR, THOMAS N.

London

Congreso; IIIrd International Paleontological Congress; 2010

With the exception of Devonian lycopsids, the oldest well-known floras from Antarctica are dated from the Permian, after the end of the Carboniferous glaciation. In this report we present a synthesis of what is currently known about the diversity, ecology and biology of plants that composed these high latitude floras. Our analysis is based on impression/compression specimens and permineralizations from several Permian assemblages. Gymnospermous trunks, stems, roots, pollen and ovulate organs of Noeggerathiopsis (cordaites), Gangamopteris and Glossopteris (seed ferns) dominate these assemblages. The proportion of these taxa varies in function of age and type of deposit, indicating the presence of several types of communities; however, the glossopterids are the most abundant and diverse group. Other taxa recognized in Late Permian permineralized peat include a fern and a moss, while compression floras indicate the presence of coniferophytes, sphenophytes, and herbaceous lycopods. Additional evidence suggests complex ecological interactions between the plants and arthropods and fungi. Wood and trunks of glossopterids, some of them in situ, indicate the presence of established forests that were well adapted to a high-latitude light regime. Permineralized specimens provide data on the development and architecture of the unusual root system (Vertebraria) of these trees, and also on vegetative regeneration, with the production of epicormic shoots and possible root suckers. These floras provide a unique opportunity to examine a number of factors relating to plant growth and community structure in high-latitude ecosystems that have no equivalent today.