A review of the glacial environment arthropod trace fossilsUmfoloziaandWarvichniumwith the description of new ichnotaxa

Abstract

AbstractTrace fossils are important records of the presence and behaviour of animals in the past, especially in deposits where few body fossils are preserved. They tend to provide the main palaeobiological record for past glacial environments, and are thus very important for understanding the ecology of these palaeoenvironments. Two ichnogenera are common in glacial sediments:UmfoloziaandWarvichnium. BothUmfoloziaandWarvichniumare attributed to arthropods; the former occurs across the Late Palaeozoic Ice Age (LPIA) and the latter occurs during both the LPIA and the Quaternary glacial event. Here, we review the stratigraphic record, ichnotaxonomy, palaeoecology, palaeoenvironments and possible tracemakers of these two ichnogenera. In addition to assessing morphological ichnotaxobases, we use multivariate morphometric analysis and inferential statistical tests to support our ichnotaxonomic revisions. The diagnosis ofUmfoloziais revised, with the description of a new ichnospecies,Umfolozia terere, and the emendation ofUmfolozia riojana(formerlyUmfolozia longula). We revisedWarvichnium, maintaining the originalWarvichnium ulbrichiand allocating two morphologies to the ichnogenusIrichnus:Irichnus saltatoriusandI. paripinnatusisp. nov. These trace fossils record several behaviours, and have implications for palaeoenvironmental interpretations and the evolution of invertebrate ecosystems. UsingUmfoloziaandWarvichniumas case studies, we demonstrate the application of morphometric analysis in ichnotaxonomy and highlight this as a tool that may be applied to other trace‐fossil groups.