Meeting Abstract

43.7  Sunday, Jan. 5 11:45  Mechanics of the Jaws and Tooth-Whorl of Helicoprion davisii, the whorl-toothed ratfish RAMSAY, JB*; WILGA, CD; TAPANILA, L; PRUITT, J; PRADEL, A; SCHLADER, R; DIDIER, DA; University of Rhode Island; University of Rhode Island; Idaho State University; Idaho Museum of Natural History; American Museum of Natural History; Idaho Museum of Natural History; Millersville University jasonramsay@mail.uri.edu

The discovery of a Helicoprion fossil containing the tooth-whorl and intact jaws shows that the symphyseal whorl occupies the majority of the lower jaw. A biomechanical model of the feeding mechanism in these Early Permian predators was developed by using the morphology of the jaws and tooth-whorl, and a reconstruction of the jaw musculature. The mechanics of the jaws and whorl suggest that hard shelled prey would tend to slip anteriorly from the closing jaws due to the curvature of the tooth-whorl, lack of cuspate teeth on the palatoquadrate and resistance of the prey. When feeding on soft-bodied prey, deformation of the prey would trap prey tissue between the two halves of the palatoquadrate and the whorl. The curvature of the tooth-whorl and position of the exposed teeth relative to the jaw joint results in tooth functions that differ from anterior to posterior tooth, which aid in feeding on soft-bodied prey. Furthermore, the paths traveled by the teeth during jaw depression are reminiscent of curved paths used with slashing weaponry and may have allowed the teeth to cut with jaw opening as well as closing.