Shell morphology and palaeoecology of Praenatica gregaria Perner, 1903 from the Koněprusy Limestone (Lower Devonian) of Bohemia (Czech Republic)


Authors: Jankovský M

Published in: Bulletin of Geosciences, volume 78, issue 4; pages: 423 - 429; Received 13 January 2003; Accepted in revised form 21 July 2003;

Keywords: Lower Devonian, Prague Basin, Gastropoda, Platyceratidae, morphological variability, colour patterns, epizoans, shell breakage,

full text (PDF, 0.28 MB)

Export to RIS



Praenatica gregaria Perner, 1903 is an Early Devonian (Pragian) gastropod that is judged to be adapted to a stationary living habit on the tegmen of camerate crinoids. More than one thousand specimens were examined in order to describe and explain the occurrence of different morphological forms. The variability of the shells was found to be closely dependent on the attachment surface. Rapid growth changes during an ontogeny demonstrate the ability to move, perhaps even change hosts. Traces of colour patterns, epizoans in situ and repaired shell fractures were observed in some cases. The reconstructed colour pattern consists of longitudinal bands often transversally crossed by growth lines lacking pigment and probably serving a sheltering function. Various epizoans showed that the empty conch served as an appropriate base for the attachment of small and fragile organisms, most commonly bryozoan colonies. The majority of the studied shell fractures were formed passively in the surf, only some of them show evidence of the activity of molluscivorous predators.