Paleobotany can contribute much to evolutionary scenario-building. Here, we use two case studies - the Devono-Carboniferous vascular plant radiation and the largely coeval evolution of heterosporous from homosporous life histories - to examine the interface between phylogeny and ecology. Our observations challenge some tenets of the neo-Darwinian orthodoxy, notably the assumed role of competition mediated selection as an active driving force, rather than a passive filter, of evolution.The Devono-Carboniferous class-level radiation of vascular plants was prompted by attainment of a complexity threshold and delimited the morphological envelope that enclosed an apparently fractal pattern of subsequent, lower level radiations. The contrast of low speciation rates with exceptionally high rates of phenotypic divergence in the Devonian suggests a non-adaptive ''novelty'' radiation, perhaps reflecting saltational evolution via ''hopeful monsters''. Successive lower level radiations were more constrained by the ecological hierarchy that resulted from progressive niche differentiation and saturation. This in turn reflected increased speciation rates, thereby completing a well defined negative feedback loop in the coevolution of phenotypic and ecological differentiation.Heterosporous life histories evolved independently in at least ten lineages. Heterospory allows the sporophyte to impose, via differential development, a single fixed gender on each gametophyte prior to spore release. Although the resulting life history is less flexible than homospory, which on recent evidence includes a range of subtle and sophisticated strategies, it promotes the sporophyte as the primary target for selection. Gametophytes effectively perform the role of gametes and are released into the environment prior to fertilization, thus favoring aquatic-amphibious habitats resistant to occupation by homosporous pteridophytes; terrestrial heterospory requires apomixis. Although the profound iteration of heterospory implies a strong adaptive advantage, repeated gradual evolution via inferior intermediates exhibiting exosporous heterospory seems unlikely.Seed-plant success reflects economic efficiency and the subsequent evolution of effective pollination syndromes, rather than integumentation of the ovule. Major radiations of heterosporous lineages and subsequently of seed-plants required perturbation of pre-existing communities by extrinsic environmental changes rather than genuinely competitive displacement. This typical manifestation of ''home-field advantage'' further emphasizes the intimate relationship between phylogeny and ecology, and allows us to make predictions that can be tested by further paleobotanical research.