XVI International Botanical Congess

The Devonian origin of the seed was a key innovation in early land plant evolution, facilitating exploitation of a range of environments and ecological strategies. The extensive fossil seed record allows evaluation of patterns in seed plant diversity and morphological (and ecological) disparity of propagules. Stratigraphic ranges and morphological data (based on discrete characters) are from a database of 600+ species. Morphological disparity of seeds (mean pairwise character distance among taxa) increased during the early Carboniferous. Seed size expanded from all small to the modern range by the mid-Carboniferous. Size distributions of families became less discrete in the mid-Carboniferous, suggesting changes in ecosystem structuring. This is supported by evaluation of temporal patterns in seed morphospace (based on principal coordinates analysis).