Bivalves - Clams and Mussels

Lang de

The Muschelkalk, literally ‘bivalve limestone’, owes its name to the abundantly found bivalves. The term was coined as early as 1761 by the Thuringian naturalist Georg Christian Füchsel and is hence one of the earliest stratigraphic terms. The shapes of bivalve shells and their occurrence in certain sediment types provide a key to palaeontologists for reconstructing Triassic palaeoenvironments. Most of the Muschelkalk fossil communities dominated by bivalves can be specified according to the sedimentary environment in:

  • soft ground communities with burrowing filter feeders and detritus feeders
  • quartz sand and carbonate sand communities with burrowing filter feeders
  • firm or hard ground and shell ground communities with sessile filter feeders

Comparably to extant burrowing bivalves, the Muschelkalk Sea was inhabited by plankton feeders which filtered their food actively, and detritus feeders, which collected food in the muddy substrate. Large scallop-like bivalves were flexibly attached or tightly cemented to shelly substrates. This applies to the oyster-like terquemiids which built small ‘bioherms’, reef-like structures that allowed a variety of other organisms to anchor on the sea floor. Most of these bivalves have calcitic shell layers and are generally better preserved than burrowing species with aragonitic shells, which are preserved as internal moulds unless the aragonite was secondarily altered to calcite.