Vegetational composition of the Early Cretaceous Chicalhão flora (Lusitanian Basin, western Portugal) based on palynological and mesofossil assemblages

摘要

A new Early Cretaceous flora is described from the Lusitanian Basin in the Estremadura region (western Portugal) based on a combined study of mesofossils and palynomorphs. The fossil specimens were extracted from samples collected in the Chicalhão clay pit complex, near the village of Juncal from sediments belonging to the Figueira da Foz Formation. The plant bearing sequence is considered to be of Late Aptian–Early Albian age. Palynomorphs and mesofossils are generally well-preserved and include about 63 taxa. The palynoflora is dominated by conifer pollen and fern spores. Angiosperm pollen is also present, but subordinate among the palynomorphs. In contrast, angiosperms completely dominate the mesofossil flora and are mainly represented by fruits and seeds. Four taxa of angiosperm flowers were also identified. The combined palaeobotanical and sedimentological evidence indicates seasonally dry climate and an open vegetation consisting of a mixed conifer forest with an understorey and ground cover of ferns and angiosperms and with patchy occurrences of lycophytes and plants of the Bennettitales–Erdtmanithecales–Gnetales (BEG) group. Angiosperms probably inhabited moister areas bordering rivers and lakes.