Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original Paper

Radek Mikuláš, Z Dvořák

Fossil biogenic structures (?invertebrate eggs) attached to mollusc shells (Miocene; North Bohemian brown coal basin, Czech Republic)

Journal of the Czech Geological Society, volume 46 (2001), issue 3-4, 374 - 378

Minute "strings" composed of spherical to oval bodies were found attached to shells of the Miocene bivalve Pseudoanodonta sp. Some strings are interrupted, and neighbouring bodies may be either broadly connected or almost separated. The same surfaces of bivalve shells show less frequently also clusters of larger circular bodies. These are densely spaced but usually not touching the neighbouring ones. Interpretation of the described structures as plant fossils (e.g., algae) is unlike; their similarity to eggs of various recent invertebrates, fish or amphibians is evident. The small size of the spherical or circular bodies makes improbable their explanation as frog eggs; the location of the bodies on external surface of bivalve shells is unlike for insects. Therefore, only the explanation of the described structures as gastropod or fish eggs seems to be realistic.