Format: ORAL

Hans Kerp1 and Michael Krings2,3

1 Universität Mu¨nster, Mu¨nster, Germany 2 Bayerische Staatssammlung fu¨r Paläontologie und Geologie, Munich, Germany 3 Ludwig-Maximilians-Universität, Germany

Aglaophyton major and Rhynia gwynne-vaughanii are commonly regarded as the less advanced plants from the Early Devonian Rhynie chert. The naked, dichotomizing axes with a simple conducting system were lying on the substrate and lacked root-like structures or rhizomes. Despite their apparent simplicity these plants had rather complex life strategies. The alternation of generations in these two taxa can be reconstructed in great detail, and the excellent and rapid fossilization in the chert even provides snapshots of the release of sperm and the gametophyte-sporophyte junction. Cyanobacterial mats appear to have been crucial for the germination of spores. A symbiosis with vesicular arbuscular mycorrhizal fungi is characteristic of both taxa and was established already in the early gametophyte stage. Aglaophyton hosted several other organisms, including cyanobacteria, mites, trigonotarbid spiders and the oldest known bona fide nematodes, the first soft-bodied animals recorded from the Rhynie chert. Apart from sexual reproduction Rhynia also propagated vegetatively.