Evolution of pinniped Carnivora with reference to other aquatic Mammalia - a case study of constructional morphology

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The origins and relationships of the Otariidae, Odobenidae and Phocidae, which are collectively referred to the Pinnipedia, remain an unresolved and controversial subject of debate. While immunological and anatomical similarities are suggestive of a monophyletic origin of the Pinnipedia, other anatomical features, in addition to their palaeobiogeographical history, are instead supportive of a diphyly. The result of this divergence is that the origin of Pinnipedia remains unresolved if only comparative analytical methods, including cladistics, are applied. While these methods are useful for establishing possible relationships between the various taxa, the reconstruction of evolutionary pathways is not possible. It is instead argued that the evolutionary pathways within the Pinnipedia, which remains the primary objective of this proposal, can be reconstructed by applying a constructional morphological analysis to the pinnipedian locomotor apparatus and bracing system. This approach is effective as despite the fact that the Otariidae, Odobenidae and Phocidae share similar overall morphologies, they differ in their aquatic and terrestrial modes of locomotion. An analysis of these locomotory options allows a physicomechanical interpretation of anatomical differences, within the context of the bracing system, and will thusly decide which of the anatomical characters currently used in phylogenetic analyses are inseparable from mechanical functional; and should be rejected. This analysis will furthermore yield the constructional base for the reconstruction of early evolution of all groups. For a better understanding of the framework of the constraints of mammalian constructions on the way to obligatory aquatic locomotion, we also plan to study the locomotion modes and their anatomical backgrounds of other aquatic or semi-aquatic mammals. This will allow us to establish hypothetical ancestral pinniped constructions, which will help to identify fossil carnivores ancestral to extant Pinnipedia. We aim to not only resolve the origin of Pinnipedia but also to establish a methodology based on morphomechanical analysis additional to classical phylogenetic analyses.