Dipterid ferns from the Mesozoic of Antarctica and New Zealand and their stratigraphical significance
Two genera of dipteridaceous ferns, Goeppertella and Hausmannia, are described for the first time from the Mesozoic Hope Bay and Botany Bay assemblages of the northern Antarctic Peninsula, and Goeppertella from the Clent Hills assemblage of New Zealand. These are the first gondwanan records outside Argentina of Goeppertella. Two new species of the genus, G. jeffersonii and G. woodii, are described from Hope Bay and Botany Bay. Based on the global distribution of Goeppertella, its occurrence in these gondwanan floras indicates that they should be assigned an Early Jurassic or possibly earlier age, contrasting sharply with recently published Late Jurassic or Early Cretaceous age assignments. A pre-Late Jurassic age for the Hope Bay and Botany Bay assemblages is further supported by independent evidence from radiometric data. An earliest Cretaceous age for these assemblages has been adopted in most recent interpretations of volcanic arc evolution and palaeogeography in this region of Antarctica, the plant-bearing beds providing direct evidence of terrestrial sedimentation: these interpretations are revised here, based upon the new evidence. The ages assigned to a number of other late Mesozoic gondwanan floras, particularly from Argentina and India, must be reconsidered since many of these were dated on the basis of comparison with the Hope Bay assemblage.