engleski

Biradiolites angulosus: Paleobiological and Paleoecological Approach

Constructional pattern of the right valve (RV) of Biradiolites (Radiolitidae, Hippuritoidea, Mollusca) consisted of a relatively thick calcitic outer shell layer (osl) characterized by compact and cellular alternations within a single shell. Turonian B. angulosus individuals were able to modify the RV calcitic outer shell layer structure as a response to a change in microenvironment. A result of the structural modifications is RV morphological variability related to ontogenetic plasticity and phenotypy. It is observed that juvenile and adult individuals are always attached by antero- or postero-dorsal shell. It means that either larvae commonly attached in the same manner or a larva attached by antero- or postero-dorsal shell had a better possibility to survive. Consequently, preferential life-orientation observed in some rudist communities is probably related to an environment characterized by generally directed water-currents.

rudist; outer shell layer; paleobiology; paleoecology; Turonian

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