Meeting Abstract
The size and shape of vertebrae within the axial vertebral column are influenced by ecology and phylogeny, in addition to body size. Parameters such as total vertebral number, and dimensions and angles of vertebral processes have been correlated with locomotor type, performance, and axial mobility. Despite studies across a wide range of extant taxa including fish to primates, these data have not been expanded towards understanding Paleozoic tetrapod biomechanics. Yet, this ancestral assemblage underwent major biomechanical innovations which enabled the evolutionary water-land transition, critical to the explosive diversification of land vertebrates. Temnospondyls were a diverse set of stem-amphibians that arose in the mid-Mississippian (346MYA) and went extinct in the Early Cretaceous (120MYA. Early works on temnospondyls described and categorized their diversity of ecologies, habitats, and gross morphologies, including complex vertebral morphologies. However, no study has quantified temnospondyl vertebral diversity in, or addressed their effects on, biomechanical metrics such as stiffness of the spine, or lever arms of epaxial musculature. We undertook a 2D geometric morphometric study of the shape differences and investigated the biomechanical consequences of pre-sacral vertebral morphology in the temnospondyls by calculating, plotting, and analyzing principal components to determine disparity patterns. We document the diversity of all aspects of centra, neural spine, and transverse process shape. Principal components separate the temnospondyls into clusters consistent with their phylogeny, body size, geological age, and, most biomechanically relevant, habitat. This project lays the groundwork for a series of quantitative studies to understand differences within this diverse group and to better understand key innovations in the axial column for terrestrial locomotion.
