Dynamics of placoderm distribution in the Prague Basin (Czech Republic)

Abstract

The occurrence of placoderms in the Prague Basin (Bohemian Massif; Czech Republic) shows a very unsteady distribution in space and time. The most abundant specimens are in the Lochkovian and, through decrease in the Pragian, they become rare towards the Givetian. The primitive acanthothoracids dominating in the Lochkovian and Pragian are completely replaced by arthrodires at the beginning of the Emsian. All placoderms in the Prague Basin, without any regard to their dimensions, had smooth jaws which is a proof of their non-predatory feeding habit. Although placoderm diversity is generally considered to reflect the Devonian nekton revolution, the abundance of these vertebrates in the Prague Basin displays a decrease, i.e. an inverse tendency to the global one.

Keywords::

• Vertebrata
• Placodermi
• Devonian
• Prague Basin

Acknowledgements

The authors thank B. Ekrt (National Museum in Prague) for his help with the collection, Š. Manda (Czech Geological Survey) for providing the template for Fig. 1B and P. Lukeš (Prague) for important information on the stratigraphy of several samples. The study was funded by the Charles University in Prague project GAUK no. 278011, SVV261203 and the project PRVOUK P44. This paper is a contribution to the International Geoscience Programme (IGCP) Project 591 – The Early to Middle Paleozoic Revolution.