New records of Early Cretaceous angiosperm pollen from Portuguese coastal deposits: Implications for the timing of the early angiosperm radiation

Abstract

Detailed and continuous palynological records from two well-dated successions in the Portuguese Algarve and Lusitanian Basins document the diversification of early angiosperm pollen during the Late Barremian to Middle Albian time interval. Based on dinoflagellate cyst biostratigraphy, an accurate stratigraphic framework has been established for the studied near-shore deposits resulting in distinct changes of the stratigraphic position of individual units. The qualitative and quantitative analysis of the palynofloras of the two sections revealed a total of 66 different types of angiosperm pollen. Most of them (55 taxa) are monoaperturate grains of magnoliid or monocot affinity. In both records, eudicots, represented by various tri- and polyaperturate taxa (11 taxa), are restricted to the Albian part of the sections. Angiosperm pollen grains display a distinct increase in both, diversity and relative abundance between the Late Barremian and the Middle Albian. Comparison with published palynofloras from other areas shows strong similarities with regard to floral composition and the timing of first appearances of particular angiosperm pollen forms. Our results indicate a new age interpretation of the well-known angiosperm mesofossil floras from the Portuguese Beira Litoral region which have been interpreted as Barremian or possibly Aptian in age. Several lines of evidence, including sequence- and biostratigraphy as well as palynology, indicate a post-Aptian age for these assemblages, hence demonstrating a major radiation phase during the Early Albian.