Fertile osmundaceae from the early Jurassic of patagonia, Argentina

Abstract

Two new compression-impression species of the Osmundaceae described from reproductive and vegetative remains are erected for the first time from the Early Jurassic of Argentina. Todites cacereii sp. nov. and Osmundopsis rafaelii sp. nov. demonstrate that two main osmundaceous reproductive morphologies; i.e., differentiated reduced or unreduced fertile laminae were already present and widespread in Gondwana by this time. On the basis of a discussion of relevant morphological characters, the phylogenetic meaning of the fossils Todites and Osmundopsis is explored. Likewise, the systematics and taxonomy of fossil taxa and their relationships with modern ones are discussed in light of current hypotheses. In this regard, because clear synapomorphies or apomorphies are not yet fully understood, it is suggested that fossil representatives are better placed in morphotaxa (Todites, Osmundopsis) than in any current genus. Nonetheless, the clear record of characters of the leptopteroid clade by the early Jurassic proves to be older than previously assumed, which also points to an earlier time of origination for the osmundaceous ferns.