The late Serpukhovian-earliest Moscovian flora from westernmost Gondwana

Abstract

Late Serpukhovian-earliest Moscovian floras are well represented in central-western Argentina by the Nothorhacopteris-Botrychiopsis-Ginkgophyllum (NBG) Biozone. These diverse plant remains have been recognised since the end of the last century from glacial and postglacial deposits of the Paganzo Group. However, the palaeoflora composed of at least thirty-two fossil species has not been fully documented until today, including reproductive structures of significant taxonomic value. Radiometric U–Pb ages of 319.57 ± 0.09 Ma and 312.82 ± 0.11 Ma constrain the stratigraphic interval where these assemblages flourished, making them one of the best-known Gondwanan palaeofloristic records of the late Palaeozoic Ice Age. This vegetation was replaced, with the incoming of common ferns and conifers, by the Krauselcladus-Asterotheca Biozone during the late Pennsylvanian. Recognising arborescent and subarborescent lycophytes, delicate fronds, permineralised stems, and abundant palynofloras enables vegetation reconstruction in this Gondwana region.