Comparative taphonomy of Quaternary and early Permian pectiniform shells

Actuopalaeontology has been widely developed to improve the interpretations of the fossil record. In the Paraná Basin, a pectiniform-dominated fossil record is remarkable in the upper Paleozoic strata, allowing one to compare their taphonomic signatures with Quaternary valves through actualistic research. This research aims to improve the biostratinomic knowledge of pectiniform fossil concentrations, leading to better environmental and ecological interpretations of the fossil record. This is based on the taphonomy of 174 Quaternary valves of Aequipecten tehuelchus collected on the foreshore of the coastal plain of Rio Grande do Sul (southernmost Brazil). We quantified fragmentation degree, left/right valve rate, corrosion, bioerosion (i.e. borings and drill holes), and encrustation. Following, we compared Quaternary pectinid data with available information on the Permian pectiniforms from the Rio Bonito Formation (Paraná Basin). Not all signatures imprinted on the Quaternary material were observed in Permian molds. However, most observed physical damages were fragmentation and abrasion of valves, while biological damages were preserved as bioerosion traces. The presence of the Quaternary Aequipecten tehuelchus on the modern foreshore, Permian Heteropecten catharinae in lower shoreface deposits, and Permian Aviculopecten cambahyensis in an estuarine environment suggests the high transportability and durability of their hard skeletons.