Sprecher
Beschreibung
Lycophytes are the most ancient lineage of vascular plants, first appearing during the Silurian (~420Ma). They underwent a divergence into two lineages: zosterophylls and lycopsids. Despite the zosterophylls initial success, they underwent a rapid decline during the mid-Devonian and vanished by the end-Devonian. By contrast, lycopsids diversified, and persist today. Explaining these divergent evolutionary trajectories remains a central question in plant evolution. Increased occupation of terrestrial environments forced early land plants into competition for space: evolutionary innovations such as roots may have provided the lycopsids with greater ecological flexibility and resilience to environmental change, underpinning their long-term survival. This project addresses this using a trait-based approach, with the first reconstruction of a zosterophyll based on 3D data. Specimens are from the Rhynie Chert Lagerstätte, a fossilised hot spring system preserving specimens in exceptional, 3D detail thanks to the silicious rich waters from the hot spring vents. Using a novel serial grinding tomography called ‘digital fossil mining’ has allowed us to sequence entire specimens encased in rock- capturing thousands of images which can be used for reconstruction. Preliminary results reveal the zosterophyll Trichopherophyton teuchansii lacked the characteristics of true roots, including root caps and hairs. In addition, it had a helical arrangement of sporangia. 3D reconstructions allow us to draw side by side comparisons between the characteristics of rooting systems, shoots and reproductive structures in lycopsids and zosterophylls and refine our understanding of key evolutionary innovations in the earliest land plants.