Revision of the Barremian fern Coniopteris laciniata from Las Hoyas and El Montsec (Spain): Highlighting its importance in the evolution of vegetation during the Early Cretaceous

Abstract

The species Coniopteris laciniata and Sphenopteris wonnacottii are heterophyllous ferns recovered from two Spanish Barremian localities, Las Hoyas and El Montsec respectively. The similarities between these species, observed in a study of a total of 66 hand specimens from both localities, indicate that they are conspecific. Following the rule of priority in botanical nomenclature, and because there are doubts about the assignment of this species to a higher taxonomic rank, the name Coniopteris is maintained. Characters of this fern and additional characters of other species of Coniopteris would support a diversification of polypod ferns during the Early Cretaceous. Metric architecture analyses suggest that the heterophylly of the plant was probably caused by the submersion of the apical part of fronds in water during their development, which would be consistent with the taphonomy of the remains in both localities.