Maastrichtian Ceratisepia and Mesozoic cuttlebone homeomorphs
Roger A. Hewitt and John W.M. Jagt
The phylogenetics of potential Mesozoic ancestors of cuttlefish of a restricted order Sepiida von Zittel, 1895 (superorder Decabrachia Boettger, 1952) is reviewed. Microstructural studies of Mesozoic homeomorphs of cuttlebones (Pearceiteuthis gen. n., Loligosepia, Trachyteuthis, Actinosepia) are consistent with their assignement to the superorder Octobrachia Fioroni, 1981. The discovery of an embryonic Ceratisepia shell in the upper Maastrichtian of the Netherlands, indicates that true Sepiida did have a pre-Cenozoic origin. Cretaceous decabrachs of the order Spirulida Stolley, 1919 do not show evidence of the dorso-anterior shell growth vectors seen in Cenozoic spirulids, sepiids and octobrachs. Separate origins of the Sepiida and Spirulida within Cretaceous diplobelinid belemnites is still the most attractive hypothesis. Ceratisepia vanknippenbergi sp. n. from the upper Maastrichtian of the Netherlands and Pearceiteuthis buyi gen. et sp. n. from the Callovian of England are described.
Key words: Cephalopods, cuttlefish, ontogeny, biomineralization, Mesozoic.
Roger A. Hewitt, 12 Fairfield Road, Eastwood, Leigh-on-Sea, Essex SS9 5SB, United Kingdom. John W.M. Jagt [mail@nhmmaastricht.nl], Natuurhistorisch Museum Maastricht, P.O. Box 882, NL-6200 AW Maastricht, the Netherlands.
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