Phylogenetic pattern and functional morphology of the musculo-skeletal architecture of the shoulder girdle in frogs (Lissamphibia: Anura)

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The shoulder girdle of frogs has evolved into an astonishing variety of musculoskeletal architectures among the extant species. Previous studies commonly addressed the bony components only, whereas the tight link between the hard-tissue (bone, cartilage) and musculature has been neglected. Functional studies have focused mostly on the pelvic girdle and hindlimbs in the context of jumping. The functional role of the shoulder girdle skeleton, girdle musculature and the various architectures remains largely unknown, especially in relation to the preferred locomotor mode of a given species. We compile a large, judiciously selected species sample in order to cover a broad taxonomic range within the Anura and to represent the major morphological shoulder girdle architectures as well as locomotor modes and body sizes. Anatomical designs are described, coded cladistically as characters, and compared in their geometric-morphometric shape. A backbone phylogeny of frogs serves to reconstruct the within-Anura evolution of the structural complex. On the basis of the given phylogeny we also expect to uncover convergences among frog species from distantly related lineages. Shape and character states will be evaluated in relation to locomotor types. From among the identified and demarcated major structural architectures, that arise from the analysis of morphology, we pick example architectures, that will be subjected to multibody dynamic and finite-element analysis in order to assess the possible functions of their components under simulated load.