A new Middle Triassic vertebrate assemblage from Miedary (southern Poland)

Abstract

The Middle Triassic remains a poorly understood time in the evolution of land vertebrates. Here, we report a new Ladinian-age vertebrate assemblage from Miedary (southern Poland). It consists of more than 20 taxa including fish (four species of Hybodontiformes, cf. Gyrolepis, Redfieldiiformes, 'Thelodus', Saurichthys, Serrolepis, Prohalecites, Ptychoceratodus), amphibians (Mastodonsaurus, Gerrothorax, Plagiosternum, chroniosuchian Bystrowiella), and reptiles (Owenettidae, Blezingeria, Nothosaurus, Tanystropheus, an additional, yet unidentified tanystropheid, the doswelliid Jaxtasuchus, and another archosauromorph, as well as eight archosauriform tooth morphotypes). Preliminary comparisons suggest biogeographic and environmental similarities with roughly contemporaneous localities known from the southwestern part of the Germanic Basin. Among differences in these two areas are the presence of a new armored archosauromorph and a surprising abundance of Tanystropheus remains in the new Polish site. Miedary is currently the richest source of three-dimensionally preserved Tanystropheus material in the world, which will be crucial for a better understanding of the preferred environment and lifestyle of this highly specialized reptile.