Nonmarine perigondwanic trace fossils from the late Paleozoic of Argentina

Abstract

The upper Paleozoic nonmarine ichnofauna from Puna, Paganzo and San Rafael basins (northwestern and western Argentina) is divided into two major associations: Carboniferous deep‐glacio‐lacustrine (Didymaulichnus assemblage) and Permian fluvial/shallow‐lacustrine trace fossil assemblages (Ancorichnus, Umfolozia and Isopodichnus ichnocoenoses). The Didymaulichnus assemblage is dominated by arthropod locomotion traces, grazing trails being common also. It is present in laminated siltstones deposited in a deep, oxygenated, glacial lake. The Ancorichnus ichnocoenosis is dominated by arthropod feeding structures in a floodplain situation. The Umfolozia ichnocoenosis is dominated by arthropod trackways in a shallow lake. The Isopodichnus ichnocoenosis consists of resting and locomotion traces of arthropods and bivalves in shallow ephemeral pools. This ichnocoenosis is a common feature of shallow ephemeral lake, channel and floodplain deposits in the stratigraphic record. Similar ichnofossils have been reported from other parts of Gond‐wana. In particular, crawling traces of Bordo Atravesado are compared with ichnofaunas from South Africa and Brazil. Some forms (e.g., Mirandaichnium, Umfolozia, Tasmanadia) represent a similar basic morphological pattern and could have been produced by a similar arthropod, widely distributed daring Late Carboniferous and Early Permian in Gondwana.