Fossil Record 24(1): 193-205, doi: 10.5194/fr-24-193-2021
Sheltered preservation in Ordovician trilobites
expand article infoOldřich Fatka, Petr Budil§, Petr Kraft|
‡ Charles University, Faculty of Science, Czech Republic§ Czech Geological Survey, Klárov 3, Prague 1, 118 21, Czech Republic| Institute of Geology and Palaeontology, Faculty of Science, Charles University, Albertov 6, Prague 2, 128 43, Czech Republic
Open Access

Articulated holaspid specimens of Placoparia Hawle and Corda, 1847and Eoharpes Raymond, 1905 entombed inside cephalopod conchs and under the remainsof large illaenid, asaphid, cyclopygid and dalmanitid trilobites from theMiddle Ordovician Šárka Formation of the Prague Basin (CzechRepublic) are described and discussed. Two such samples were also found inthe overlying Dobrotivá Formation of Middle/Late Ordovician age. Fourarticulated juvenile exoskeletons of Placoparia preserved under a cephalon of thecyclopygid trilobite Degamella Marek, 1961 represent the first record of shelterstrategy of non-holaspid trilobites. The sheltered preservation oftrilobites could be explained by a hiding behaviour associated with thedanger of predation, storm disturbances, seeking for food or highvulnerability after moulting. It is obvious that Placoparia and Eoharpes deliberately enteredthe restricted space under skeletal parts of large trilobites or insidecephalopod conchs. These exceptional finds provide a new insight in the lifestrategy of some Ordovician benthic trilobites and are classified as casesof “frozen” behaviour.