Articles | Volume 19, issue 1
Research article
15 Jan 2016
Research article |  | 15 Jan 2016

The westernmost occurrence of Gnathorhiza in the Triassic, with a discussion of the stratigraphic and palaeogeographic distribution of the genus

P. Skrzycki

Abstract. The paper refines the taxonomic assignment of the only representative of the dipnoan genus Gnathorhiza from the Lower Triassic of Poland. It is assigned here to Gnathorhiza otschevi on the basis of morphological and biometrical similarity with the tooth plates from coeval strata of the European part of Russia. The material is comprised solely of tooth plates, both the upper and the lower ones. It comes from karst deposits of the Czatkowice 1 locality (southern Poland) dated to late Olenekian, Lower Triassic. The presence of G. otschevi in southern Poland widens its palaeobiogeographic Triassic record by more than 2000 km to the west. Czatkowice 1 locality is the only known occurrence of gnathorhizids within the Germanic Basin. G. otschevi from Czatkowice 1 shows petrodentine in the tooth plate. Its presence is proved for the first time in a Triassic gnathorhizid. Gnathorhiza was most widely distributed during the Permian and restricted to Europe in the Triassic. Tooth plates of both Early Triassic European and Late Permian Brazilian gnathorhizids are more similar to each other than to Permo-Carboniferous American ones.

Short summary
In my paper I describe the fossil material from Lower Triassic Czatkowice 1 locality in southern Poland. The material was included to dipnoan genus Gnathorhiza in 2003, and in the present paper I provide its specific assignment. Based on comparison with other Gnathorhiza species the Polish material belongs to Gnathorhiza otschevi, which is known from the European part of Russia. I have also summarized relationships, the stratigraphic and palaeogeographic distribution of Gnathorhiza.