Large onychites (cephalopod hooks) from the Upper Jurassic of the Boreal Realm

Hammer, Øyvind, Hryniewicz, Krzysztof, Hurum, Jørn H., Høyberget, Magne, Knutsen, Espen, and Nakrem, Hans A. (2013) Large onychites (cephalopod hooks) from the Upper Jurassic of the Boreal Realm. Acta Palaeontologica Polonica, 58 (4). pp. 827-835.

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Abstract

We report on the discovery of large cephalopod arm hooks (mega−onychites) from the Kimmeridgian and Volgian of Spitsbergen (Agardhfjellet Formation). This includes a largely uncompressed hook in a seep carbonate, with preservation of surface sculpture. We suggest the use of logarithmic spirals as morphological descriptors for the outer part of cephalopod arm hooks, with implications for systematics and functional morphology. Comparison with Upper Jurassic material from Greenland, northern Norway and the North Sea demonstrates a remarkably consistent morphology, which we assign to the same form species, Onychites quenstedti. Considering the relatively small stratigraphic (Kimmeridgian–Volgian) and biogeographic (Boreal) range of this large form, it is likely that it represents a single biological species or genus.

Item ID: 49586
Item Type: Article (Research - C1)
ISSN: 1732-2421
Keywords: Onychites; cephalopod hooks; Jurassic; Spitsbergen; Boreal
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This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Date Deposited: 17 Jul 2017 05:36
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040308 Palaeontology (incl Palynology) @ 100%
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