Reproductive Structure and Organization of Basal Angiosperms from the Early Cretaceous (Barremian or Aptian) of Western Portugal

Abstract

A survey of five mesofossil floras from the Early Cretaceous (Barremian or Aptian) of Portugal documents considerable taxonomic and structural diversity among early angiosperms. Currently ca. 140–150 different angiosperm taxa have been identified in these floras, of which ca. 85% are taxa at the magnoliid grade—perhaps also with some basal monocots. Evidence is beginning to emerge that those lineages identified as basal among angiosperms in phylogenetic analyses (recently referred to as the ANITA grade of basal magnoliids, including Amborellaceae, Nymphaeales, Illiciales, Trimeniaceae, and Austrobaileyaceae) were already well represented in the Early Cretaceous, at which time they were probably more diverse than they are today. Many of the fossil angiosperms from the Portuguese floras cannot be assigned to any existing group, and there is clear evidence of significant extinction.