Meeting Abstract
Most fishes today have paired pectoral fins attached laterally or ventrally to their shoulder girdles, which they use to generate thrust or lift in swimming. Iniopterygians, an order of marine Pennsylvanian cartilaginous fishes primarily from North America, had pectoral fin forms located at the nape and sometimes attached to the skull. This placement is not observed among living fishes, and little is known how such unique paired fin position affects locomotion and hydrodynamics. Previous studies conducted on living fishes (labriforms and salmonids) with laterally attached pectoral fins have demonstrated a relationship between locomotion and fin aspect ratio, a metric combining fin span and area. High aspect ratio fins are long and narrow and associated with greater speed and lift, while low aspect ratio fins are short and stubby and used for maneuvering. We experimentally tested whether the same properties apply to the diverse, dorsally-positioned pectoral fins of Iniopterygians. We hypothesize that both the low and high aspect ratio fins located at the nape are likely to induce greater lift than those located more ventrally, based off Bernoulli’s principle, and thus diversity in form likely results from additional functionality. We will use image mapping and 3D modeling software to accurately create computer and 3D printed models of five Iniopterygian taxa. Computational Fluid Dynamics software are used to analyze the forces acting the computer models. To sum the magnitude of lift and drag force acting on the physical model, digital particle image velocimetry will be used, as is standard for similar tests of living fishes. This study represents the first experimental test of fin function in these extinct fishes.
