Dzik,
J. & Sulej, T. Mass
accumulations of vertebrate fossils in the tetrapod “graveyard” at Krasiejów
near Opole, SW Poland, occur in a vast lacustrine marly claystone horizon and
claystone lenses of various extent within fluviatile cross-laminated mudstone.
These fossil assemblages do not differ from each other in taxonomic
composition, but the proportions of aquatic to land animals are dramatically
different. We attempted to separate these two components of the assemblages to
restore the original composition of the biota. The lacustrine biocoenosis
component of Krasiejów includes characean algae, various molluscs and
arthropods, ganoid and dipnoan fishes, tanystropheid prolacertilians, the
phytosaur Paleorhinus, and the most common vertebrate is the temnospondyl amphibian Metoposaurus.
The capitosaurid labyrinthodont Cyclotosaurus probably occupied the
lake shore. The inland vertebrate community was dominated by the herbivorous
aetosaur Stagonolepis and the small
dinosaur Silesaurus,
which probably were the prey for the rauisuchian Teratosaurus. The
geological age of the Krasiejów strata can be determined, although with a
rather low resolution, based on position of various members of its fauna in
their evolutionary lineages. Biostratigraphic and sequence stratigraphy
evidence may improve the precision of this dating to correspond with the upper
part of the Weser Formation in Germany, believed to be of Late Carnian age. |