Early angiosperm diversification: The diversity of pollen associated with angiosperm reproductive structures in Early Cretaceous floras from Portugal

Studies of five mesofossil floras from the Early Cretaceous (Barremian or Aptian?) of Portugal document a previously unrecognized diversity of angiosperms exceeding that currently known fi om other localities of this age. At the Famalicao, Vale de Agua, and Buarcos localities angiosperms are represented by about 100 different kinds of flowers, fruits, seeds, and stamens. At the other two localities (Torres Vedras and Catefica) angiosperm diversity is lower but still significant. At each of the five localities between 7 and 26 types of angiosperm pollen have been recognized based on pollen grains in situ within anthers, or on stigmatic or fruit surfaces. Monocolpate, dicolpate, periporate, and tricolpate angiosperm pollen have been recognized, but in all cases monocolpate grains, of probable magnoliid or monocotyledonous affinity, are the most diverse element. The diversity of angiosperm pollen in situ, or associated with other angiosperm reproductive structures, is greater than that of the dispersed palynoflora from the same localities. The diversity and abundance of angiosperms in the Portuguese mesofloras contrast strongly with the apparent paucity of angiosperm pollen in dispersed palynofloras, as well as the scarcity of angiosperm wood and leaves in Barremian-Aptian fossil plant assemblages. This discrepancy may reflect the widespread occurrence of both insect pollination and herbaceous habit among the angiosperms in the initial phases of their Early Cretaceous diversification.