Colonisation of disturbed deltaic paleoenvironments from the Early Cretaceous (Albian): Inferences from an exceptional record of the fern Ruffordia goeppertii (Dunker) Seward from northeastern Spain

Abstract

Exquisitely well-preserved records of a nearly monospecific assemblage of in situ specimens in growth position of the fern Ruffordia goeppertii from the Albian deposits of northeastern Spain, clarify Early Cretaceous continental paleoenvironments during a key epoch of floral evolution during the Cretaceous Terrestrial Revolution. These macro and microfossils of vegetative and fertile organs are preserved in connexion with their rhizomes, and spores are retained within sporangia. This assemblage contains the first records of this iconic Cretaceous fern from the Albian of Spain. The fossils also fill a temporal and geographical gap in the distribution of this taxon in southwestern Eurasia during an interval of rapid floristic and faunal changes, globally. The biostratinomy of these fossils aid reconstruction of the paleoenvironments in which this type of ferns developed, and indicates that disturbed deltaic floodplains were colonised by Ruffordia in southwestern Eurasia during the Albian. Moreover, the presence of plant-insect interaction traces on this fern and the relationship of this plan fossil assemblage with evidence of herbivorous dinosaur tracks provides insights into the possible feeding strategies of these animals in deltaic-estuarine environments during the late Early Cretaceous in southwestern Eurasia.