Cretaceous diversification of angiosperms in the western part of the Iberian Peninsula

The classic leaf fossil floras from the Cretaceous of the Lusitanian Basin, Portugal, which were first described more than one hundred years ago, have played an important role in the development of ideas on the early evolution of angiosperms. Insights into the nature of vegetational change in the Lusitanian Basin through the Cretaceous have also come from studies of fossil pollen and spores, but the discovery of a series of mesofossil floras containing well-preserved angiosperm reproductive structures has provided a new basis for understanding the systematic relationships and biology of angiosperms at several stratigraphic levels through the Cretaceous. In the earliest mesofossil floras from the Torres Vedras locality, which are of probable Late Barremian-Early Aptian age, angiosperms are surprisingly diverse with about 50 different taxa. In slightly later mesofossil floras, which are of probable Late Aptian-Early Albian age, the diversity of angiosperms is still more substantial with more than hundred different kinds of angiosperm reproductive structures recognized from the Famalicão locality alone. However, this early diversity is largely among angiosperm lineages that produced monoaperturate pollen (e.g., Chloranthaceae, Nymphaeales) and early diverging monocots (Alismatales). Eudicots are rare in these Early Cretaceous mesofossil floras, but already by the Late Cenomanian the vegetation of the western Iberian Peninsula is dominated by angiosperms belonging to various groups of core eudicots. The Normapolles complex is a particularly conspicuous element in both mesofossil floras and in palynological assemblages. In the Late Cretaceous mesofossil floras from Esgueira and Mira, which are of Campanian-Maastrichtian age, core eudicots are also floristically dominant and flowers show great organisational similarity to fossil flowers from other Late Cretaceous floras described from other localities in Asia, Europe and North America.