New evidence for Peltaspermales reproductive structures and their relationships to fronds in the Gondwana Triassic

Abstract

T he reproductive structures of the Peltaspermales from the Cañadón Largo Formation, Middle-Upper Triassic, Santa Cruz Province, Argentina, are described. In the Peltaspermaceae, the following were identified: Peltaspermum thomasii and Peltaspermum sp. cf. Peltaspermum turbanatum. Both species are the first record in Argentina and the second in Gondwana. A complete strobilus and isolated megasporophylls were found in P. thomasii. In the Matatiellaceae, complete strobili of Matatiella rosetta were described, since those previously recorded in other Argentina formations correspond to isolated megasporophylls. The association of reproductive structures with the fronds has been established and the palaeobiogeographic distribution has been provided. A new association of Scytophyllum neuburgianum fronds in organic connection with a microsporangiate cone of Bomfleuranthus gen. nov. and both co-occurrence with megasporangiate strobilus of M. rosetta has been proposed. These new records of Peltaspermales from Argentina have revealed the diversity and complexity of these plants during the Triassic. The identification of species such as P. thomasii, Peltaspermum sp. cf. P. turbanatum, and M. rosetta, together with the description of the new genus and species Bomfleuranthus scytoconnexus, not only enriches our understanding of the peltaspermal group, but also provides new information on the evolutionary relationships and adaptations of these plants in a changing ecosystem.