Meeting Abstract
56.4 Sunday, Jan. 5 14:15 Digital reconstruction of the skull of Tiktaalik roseae with insights into early tetrapod feeding mechanics LEMBERG, JB*; ROSS, CF; SHUBIN, NH; DAESCHLER, EB; University of Chicago; University of Chicago; University of Chicago; Academy of Natural Sciences of Drexel Univ. lemberg@uchicago.edu
Recent studies of the feeding mechanics of early tetrapods have focused on the adaptation of an aquatic suction feeding mechanism to one capable of feeding on land. Tiktaalik is an important transitional taxa at the boundary of the fin-to-limb transition that exhibits early examples of tetrapod-like characteristics in the cranium. The platyrostral condition of early tetrapods is first seen in elpistostegids, but its functional consequences for aquatic feeding are not fully understood. By comparing Tiktaalik with extant platyrostral taxa, like Alligator and gars, we can bound our inferences of the function of early tetrapod morphology. Patterns of cranial sutures are hypothesized to provide information about suction feeding versus biting. Crocodilians and gars possess broad scarf joints along their tooth rows. It is hypothesized these rostral scarf joints are adaptations for resisting torsion incurred during unilateral biting. Similarly the derived secondary palate of crocodilians is hypothesized to resist torsional loads. Here, we used computed tomography (CT) data of several Tiktaalik specimens, to digitally reconstruct cranial morphology and define areas of sutural contact between bones. Anteriorly, the rostrum of Tiktaalik is characterized by scarf joints, and posteriorly the squamosal broadly overlaps the quadrate and pterygoid. Medially the postorbital forms a complex suture with the postfrontal, which immediately overlays the prootic process of the braincase. The region of bones bounded by these sutures overlay approximately two-thirds of the tooth row, a robust palate, and the adductor chamber. Comparing this morphology with gars and crocodilians suggests a feeding system capable of resisting torsion incurred during unilateral biting.
