Mega-onychites from the Middle and Upper Jurassic of Poland
Durska, Ewa; Dembicz, Krzysztof
published: Jun 1, 2015
ArtNo. ESP155027603004, Price: 29.00 €
The Jurassic rocks of the Polish Jura Chain yielded arm hooks of cephalopods (megaonychites) that have never been previously reported from Poland. Four specimens found in Callovian and Oxfordian deposits are described and illustrated herein and compared with taxa of the Submediterranean Province (Swabian Jurassic). These onychites specimens were assigned to three species, namely: Onychites ornatus, O. cf. rostratus and a new species, O. kefiri sp. nov. The new species differs from the most similar O. ornatus in its more rounded shape. Two other species were previously described by Quenstedt (O. ornatus from the Callovian “Braunjura ζ” and O. rostratus from the Lower Kimmeridgian “Weißjura γ”). Given that cephalopod hooks are made of chitin and therefore have low fossilization potential, onychites could be preserved due to oxygen depleted conditions at the bottom, or because of fast burial.