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Frequency of shell anomalies in Ordovician gastropods from Šárka Formation, Prague Basin
Šoobová, Adéla ; Frýda, Jiří (advisor) ; Mergl, Michal (referee)
The master thesis focuses on the frequency of anomalous structures on Ordovician gastropod shells coming from the Šárka Formation (Prague Basin) and deposited in the collections of the National Museum. The thesis summarized basic knowledge about teratological damage in different groups of gastropods, location and shape of damage and their possible causes. On the basis of extensive data collection on the occurrence of anomalous structures on gastropod shells (more than 4000 gastropod shells were analysed), differences in the frequency of teratological damage between different gastropod species (genera), their ontogenetic stages and different shell morphologies are quantitatively tested. Analyzes were performed by Fisher's exact test using the Holm-Bonferroni correction. The results of the thesis revealed an extremely low frequency of teratological damage in the Mid-Ordovician gastropods, a statistically significant difference in the frequency of damage between different gastropod species (genera), as well as between different shell morphologies and their ontogenetic stages. New results also confirm the increasing frequency of predation marks on gastropod shells during the Phanerozoic. Key words: gastropods, molluscs, shell, anomaly, damage, predation, frequency, Šárka Formation, Prague Basin
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