Preliminary report on the microvertebrate faunal remains from the Late Triassic locality at Krasiejów, SW Poland

Abstract

Fossil vertebrate remains from the Keuper unit in the vicinity of the village of Krasiejow have been analyzed for almost two decades. However, the main goal of these works was focused mainly on large vertebrates. Here the authors present the first description of microvertebrate fossils from that site. The collection of around 5,000 specimens is mainly comprised of teeth and scales. The most numerous remains belong to osteichthyans: dipnoans ( Ptychoceratodus and cf. Arganodus ), palaeoniscids, semionotids, redfieldiids and chondrichthyans, such as Lonchidion sp., which is the first indisputable record of that genus in the Upper Triassic of Poland and the first shark at the Krasiejow locality. Tetrapod fossils consist of temnospondyl amphibians, rhynchocephalian lepidosauromorphs and archosauromorphs. Among them, temnospondyl amphibian remains are the most numerous and are represented mostly by Metoposauru s. However, on the basis of diversity in tooth morphotypes, the occurrence of other taxa cannot be excluded. Rhynchocephalians are composed of 7 fragmentary jaw morphotypes with dentition, which could indicate high taxonomic diversity (cf. Planocephalosaurus , cf. Diphydontosaurus and cf. Clevosaurus ). The most varied fossil group was assigned to the archosauromorphs. The authors can distinguish at least 19 teeth morphotypes, which show similarities to the dentition of: protorosaurians (cf. Tanystropheidae), pseudosuchians (cf. Protecovasaurus , cf. Revueltosaurus ) , early crocodylomorphs and basal sauropodomorph dinosaurs. The first occurrence of a theropod dinosaur and cynodonts at the Krasiejow locality is also recorded. However, their remains are very rare. These new records show a high taxonomic diversity at the Krasiejow locality that contributes to our deeper understanding of Late Triassic ecosystem of Poland.