Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)

Several notes to the functional morphology of remopleurid and ellipsotaphrid trilobites of the Prague Basin

 

Petr Budil, Oldřich Fatka, Michal Mergl, Pavel Bokr

Geoscience Research Reports 45, 2012 (GRR for 2011), pages 102–106

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Abstract

The general body morphology of remopleurid and ellipsotaphrid trilobites of the Prague Basin suggests that these trilobites belong to active nektobenthic to nektic swimmers. Several life strategies are supposed in different evolutionary lineages: Amphitryon Hawle & Corda and possibly also Apatokephalus Bragger were, very probably, rather nektobenthic animals. Flat ventral side of the exoskeleton as well as flat free cheeks (with long narrower genal spines in Apatokephalus) and the visual surface of eyes forming relatively narrow strip oriented especially frontally, laterally and posteriorly but not ventrally suggest this mode of life. Glabella together with palpebral lobes and eyes form steeply delimited platform which enable an excellent outlook for the animal, even in these benthtic to nektobenthic forms. In contrast, Girvanopyge Kobayashi, (= Cremastoglottos Whittard fide Fortey and Owens = Gamops Šnajdr fide Vaněk and Valíček), Ellipsotaphrus Whittard and Sculptaspis Nikolaisen are considered as distinctly better swimmers with possibly nektic mode of life. Their general morphology is supposed to represent a distinct convergence to the cyclopygid trilobites (many authors consider Girvanopyge for cyclopygid up to now). The free cheeks are reduced (especially anteriorly), the cephalon is more vaulted and the visual surface of the eyes covers, at least partially, even the ventral cephalic surface. Our opinion fits well with the concept of Shiino et al. (2012 and pers. com. 2012) supposing differences in the life habits within different groups of remopleuridids. Only Apatokephalus and Amphitryon occurred as common elements, meanwhile the other representatives belong to very rare taxa in the Prague Basin.