Middle Triassic ammonoids from Silesia, Poland

Abstract

Adescription of new ammonoid specimens (Acrochordiceras aff. damesi,cf . Acrochordiceras sp. indet., DiscopĘchites cf. dux, ?Paraceratites sp., cf. Balatonites sp. indet., Beneckeia buchi) from the Lower Muschelkalk (Anisian, Middle Tnassic) of Silesia (southern Poland) is presented. The detailed stratigraphic position of the new finds is given. The description is supplemented with a list of all species of ammonoids found hitherto in Silesia, which was a southern part of the Germanic Basin during the Anisian. Beneckeia and Noetlingites were typical of epicontinental seas and usually appeared in the early part of fransgressions. Other ammonoids entered from the Tethys into the epicontinental sea of the Germanic Basin during the maxima of fransgressions. Some of them (balatonitids, paraceratitids, bulogitids, Discoptychites and probably Acrochordiceras) were successful colonizers which established their own populations in the Germanic Basin and evolved towards morphologies typical of epicontinental seas. Other (Beyrichites sp., Paraceratites binodosus, and'Trachyceras' sp.) are regarded as unsuccessful immigrants or empĘ shells drifted post-mortem from the Tethys.