Microanatomical diversity of amniote ribs: an exploratory quantitative study |
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Authors: | Aurore Canoville Vivian de Buffrénil Michel Laurin |
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Institution: | 1. Bonn University, Steinmann Institute for Geology, Mineralogy and Paleontology, Bonn, Germany;2. CR2P, Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, Sorbonne Universités, CNRS/MNHN/UPMC, Muséum National d'Histoire Naturelle, Batiment de Géologie, Paris, France |
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Abstract: | Bone microanatomical diversity in extant and extinct tetrapods has been studied extensively, using increasingly sophisticated quantitative methods to assess its ecological, biomechanical and phylogenetic significance. Most studies have been conducted on the appendicular skeleton, and a strong relationship was found between limb bone microanatomy and habitat preferences. Few comparative studies have focused on the microanatomy of the axial skeleton and its ecological signal. In the present study, we propose the first exploratory study of the microanatomical diversity of amniote ribs. Our comparative sample comprises 155 species of extant amniotes and encompasses the taxonomic, ecological, and body size diversity of this group. We standardized our sampling location to the midshaft of mid‐dorsal ribs. Transverse sections were obtained from classical petrographic methods, as well as by X‐ray microtomography. Most of the microanatomical and size characters of the ribs display a phylogenetic signal, which is an expected result and is also observed in amniote limb bones and vertebrae. We found a significant relationship between rib cortical thickness, global compactness, and lifestyle. As for the vertebrae, the development of the spongiosa in the medullary region appears to be strongly correlated with size. Even though an ecological signal was found in the inner structure of the ribs, additional work is needed to document the intra‐individual variability of the rib microanatomy along the rib cage and within a single element. |
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Keywords: | axial skeleton virtual sections comparative analysis lifestyle adaptation body size bone microstructure compactness |
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