Format: ORAL

Alexander J. Hetherington

University of Edinburgh, Edinburgh, United Kingdom

Land plants exploded in complexity during the Silurian and Devonian periods during the primary radiation of vascular plants. This radiation saw plants diversify from tiny species, that we predict occupied marginal habitats, and culminated in the origin of the first forests covering large swathes of the terrestrial surface by 385 million years ago. The diversification of vascular plants occurred in parallel to, and was likely underpinned by, the origin of the modern vascular plant sporophyte body plan delineated into distinct roots, shoots and leaves and connected by a highly efficient vascular transport system. Despite the evolution of the vascular plant body plan being one of the most important events in plant evolution many key questions still remain about how and when it evolved. The fossil record provides our only direct evidence for the steps involved in the evolution of the complex vascular plant body plan and despite its biased and fragmentary record it remains invaluable for shaping our understanding of plant evolution. Numerous fossil sites from around the world have helped shape our views on the diversification of vascular plants but one of the most important fossil sites has been the Rhynie chert from Aberdeenshire, Scotland. This single fossil site, preserving an entire407 million year old ecosystem with exceptional preservation, has been transformative for plant evolution. Despite being discovered over 100 years ago new imaging and digital reconstruction techniques are underpinning a resurgence of research on the site. Here I present recent advances in our understanding of the plant species in the Rhynie chert and outline how these fossils are contributing to our understanding of the evolution of plant complexity.