Accepted abstract for ICVM 2010 meeting
XROMM analysis of 3D maxillary movements effecting kinethmoid rotation and powering jaw protrusion in Cypriniform fishes
- Brown University, Providence, RI, USA
- The George Washington University, Washington D.C., USA
Abstract accepted for the 9th International Congress of Vertebrate Morphology, July 26-31 2010, Punta Del Este, Uruguay.
Jaw protrusion is an important component of food acquisition in suction-feeding fishes. Various jaw protrusion mechanisms have evolved independently; among the most striking is that seen in cypriniform fishes. Though the exact mechanism of cypriniform jaw protrusion has not been thoroughly investigated, most research has focused on the function of a novel sesamoid ossification in cypriniform skulls — the kinethmoid. This bone rotates anteriorly as the premaxillae protrude, but the kinematics are unclear. This midline bone is supported by a ligamentous meshwork, tethering it to the palatines, premaxillae, neurocranium, and maxillae; this underscores its importance to the jaw protrusion mechanism while simultaneously making 3D kinematic reconstruction difficult. We use XROMM to visualize kinethmoid movement in-vivo, as well as movements of the maxilla, premaxilla, lower jaw and neurocranium in common carp, Cyprinus carpio. XROMM builds accurate, precise reconstructions of skeletal structures in both movement and morphology, allowing comparison of the timing and extent of multiple bones' movements in 6 degree-of-freedom space. Functional decoupling of jaw systems — i.e. oral vs. pharyngeal — has been hypothesized to drive evolutionary diversification in multiple lineages of fishes. We test previously proposed hypotheses of cypriniform oral jaw protrusion and highlight the potential for the kinethmoid-mediated protrusion mechanism to decouple upper jaw protrusion from lower jaw depression.
Pictures and movies can be found on the associated project page:
Fish Feeding: Biomechanics of jaw protrusion in common carp »
