Data from: Head-turning morphologies: evolution of shape diversity in the mammalian atlas-axis complex

• Main Authors: Vander Linden, Abby, Campbell, Kristin M, Bryar, Erin K, Santana, Sharlene E
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2019
• Subjects: Equus zebra; Tupaia glis; Erythrocebus patas; Macropus robustus; Dendrohyrax arboreus; Dromiciops gliroides; cervical vertebrae; Eumetopias jubatus; Petaurus breviceps; Tadarida brasiliensis; Hystrix cristata; Trichechus manatus; Cervus elaphus; Manis pentadactyla; Giraffa camelopardalis; Phoca vitulina; Antilocapra americana; Myocastor coypus; Sorex bendirii; Orycteropus afer; Tamandua tetradactyla; Martes pennanti; Sarcophilus harrisii; Trichosurus caninus; Lepus americanus; Rhinolophus ferrumequinum; Hipposideros dinops; Didelphis virginiana; Erethizon dorsatum; Suricata suricatta; Galago senegalensis; Dipodomys microps; Spherical harmonics analysis; Phascolarctos cinereus; Canis lupus; Atelerix albiventris; Puma concolor; Geocapromys ingrahami; Potorous tridactylus; Bison bison; Ochotona princeps; Berardius bairdii; Acrobates pygmaeus; Tachyglossus aculeatus; Myoprocta pratti; Emballonura semicaudata; Octodon degus; Symphalangus syndactylus; Chinchilla lanigera; Saimiri sciureus
• Online Access: https://doi.org/10.5061/dryad.1nq8md7

Mammals flex, extend, and rotate their spines as they perform behaviors critical for survival, such as foraging, consuming prey, locomoting, and interacting with conspecifics or predators. The atlas-axis complex is a mammalian innovation that allows precise head movements during these behaviors. While morphological variation in other vertebral regions has been linked to ecological differences in mammals, less is known about morphological specialization in the cervical vertebrae, which are developmentally constrained in number but highly variable in size and shape. Here, we present the first phylogenetic comparative study of the atlas-axis complex across mammals. We used spherical harmonics to quantify 3D shape variation of the atlas and axis across a diverse sample of species, and performed phylogenetic analyses to investigate if vertebral shape is associated with body size, locomotion, and diet. We found that differences in atlas and axis shape are partly explained by phylogeny, and that mammalian subclades differ in morphological disparity. Atlas and axis shape diversity is associated with differences in body size and locomotion; large terrestrial mammals have craniocaudally elongated vertebrae, while smaller mammals and aquatic mammals have more compressed vertebrae. These results provide a foundation for investigating functional hypotheses underlying the evolution of neck morphologies across mammals. ATLAS stls pre-analysis STL files of atlas vertebrae for all species. Meshes are watertight (transverse foramina and vertebral foramina have been filled), smoothed, and reduced to 20k triangles in preparation for spherical harmonics analysis. AXIS stls pre-analysis STL files of axis vertebrae for all species. Meshes are watertight (transverse foramina and vertebral foramina have been filled), smoothed, and reduced to 20k triangles in preparation for spherical harmonics analysis. ATLAS landmarks Landmark files for all specimens used for registration of 3D atlas meshes in spherical harmonics analysis. AXIS ...