THE PHYSIOLOGICAL DIVERSIFICATION PATTERNS OF VASCULAR PLANTS DURING THE LATE PALEOZOIC AND MESOZOIC (Invited Presentation)

Morphological traits directly preserved in leaf fossils can inform the evolution of lamina physiology and lamina development. The late Paleozoic-early Mesozoic had a significant taxonomic diversification and turnover amongst the non-flowering seed plants and other vascular plant lineages of the time. These turnovers can be associated with the expansion and the subsequent loss of wetlands, a global pattern linked to climate transitions and assembly of Pangea. Exploration of this turnover finds different trajectories through time for developmental and physiological evolution. The most significant developmental diversification occurred during the Carboniferous. However, an important expansion of physiological diversity occurred among seed plants in the Permian and Triassic at a time when a developmental focus would suggest an active contraction of disparity. This physiological diversification can be attributed exclusively to seed plants, while ferns remained relatively stable regarding physiological and developmental diversity throughout the evaluated time frames. Tolerating the stresses of drier environments has long been expected to have shaped seed plant evolution. However, perception of evolutionary trajectories can be highly divergent depending on how the patterns are dissected.