Palaeontology of decabrachiate Cephalopoda - an ultrastructural approach to their morphogeny and phylogeny

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Until today, neither neontological nor palaeontological approaches have been able to clarify the origin and the phylogeny of the decabrachiate Coleoidea. This problem is mainly due to a comparatively poor fossil record. However, new (not yet studied) shells of key taxa such as Naefia, Groenlandibelus, and Conoteuthis have recently appeared from the Late Cretaceous of Japan and Canada. Their original (unaltered) shells provide an unique possibility to get new insights into the still unclear shell construction as well as the enigmatic origin of the decabrachiate gladius. It is therefore the goal of the present project to study the shell ultrastructure of Naefia, Groenlandibelus, and Conoteuthis with SEM, to compare it with other pre-Cenozoic, Cenozoic, and Modern decabrachians, as well as with belemnoid coleoids. Thus, a convincing and applicable model of the coleoid shell construction shall be established. The results will be integrated in a combined cladistic analysis consisting of morphological and molecular data.