Meeting Abstract
Most fish species have a hole that passes through the center of each vertebrae, called the “notochordal foramen.” Since the notochord passes through the foramen, its size and shape likely affects the mechanical properties of the fish vertebral column. In this study, we quantified the size and shape of the notochordal foramen and the overall vertebrae in 72 actinopterygian species. We used micro-computed tomography scans from oVert (openVertebrate) scans downloaded from Morphosource.org to measure the anterior and posterior angles of the vertebral cones, the diameters of the vertebrae, and the canal diameters and centrum lengths at the vertebrae that were located at equidistant points along the body length of each fish. In order to determine these points, we measured the standard length of each fish and and quantified these parameters for vertebrae spaced every 10% along the body. Mapping the morphological parameters to a recent actinopterygian phylogeny using fishtree and phytools R packages, we found that the notochordal foramen shows a pattern of decreasing diameter throughout the evolutionary history of teleosts. A few groups do not follow this pattern, because they have a larger notochordal foramen diameter than the ancestral state. These patterns indicate that the existence of a large notochordal foramen is an important trait in the locomotor biomechanics of some species that have convergently evolved and persisted, despite a general trend of reduction across actinopterygians.
