Triassic fish faunas from Miedary (Upper Silesia, Poland) and their implications for understanding paleosalinity

Abstract

We describe two new fish-dominated faunas from the Middle Triassic (Ladinian) Miedary site, Upper Silesia, Poland, and present a comparative analysis of Middle-to-Late Triassic vertebrate assemblages from the Germanic Basin, in order to explore the influence of salinity on faunal composition. The composition of the assemblage from dolomite beds at Miedary is similar to those from the Muschalkalk facies, whereas the assemblage from glauconite beds appears to be the first brackish vertebrate assemblage of the Serrolepis lake-type recognized from the eastern Germanic Basin. Comparative analysis of all sites, using hierarchical clustering, nonmetric multidimensional scaling, and principal component approaches, revealed the existence of vertebrate taxa associated withfreshwater, brackish and marine conditions, as well as euryhaline taxa with wide salinity preferences. Moreover, it confirms the brackish nature of Serrolepis -bearing assemblages, and suggests that Serrolepis suevicus is a brackish specialist, indicative of oligohaline to miohaline paleosalinities. The Middle-Late Triassic vertebrate faunas appear dominated by stenohaline taxa, with a conspicuous separation of species living in the freshwater and marine conditions. The euryhaline taxa are rare, and comprise Acrodus lateralis , Eusauropterygia, Lissodus nodosus , and Saurichthyiformes. • Two new fish assemblages from the Middle Triassic of Europe are described. • Paleoenvironmental signature of Serrolepis-lake assemblages is confirmed. • There is noticeable relationship between aquatic assemblage composition and paleosalinity. • Preferred salinity ranges for various Mid-Late Triassic vertebrates are proposed. • Sufficient sampling and quantitative data are crucial for comparative studies on paleosalinity.