EVALUATING CHANGES IN MORPHOMETRY AND PALEOECOLOGY OF FAMILY TRIGONIIDAE (MOLLUSCA: BIVALVIA)

The family Trigoniidae are common fossils in Jurassic and Cretaceous rocks; however, this dominant family of burrowing bivalves have not been examined using modern shape analysis techniques. Trigoniidae have specialized hinge morphology, complex hinge teeth with secondary dentition were developed in order for the large muscular foot to function. The oversize hinge prohibits a common burrowing adaptation which other bivalves possess, a prosogyrous (curved forward) beak, and as a result the family developed a unique shell structure and ornamentation to aid in burrowing which is co-adaptive to the dentition.

This study aims to investigate the morphometry of the shell, the exterior and interior, and its relationship to developmental changes, as well as the adaptation with respect to changes in environment. A pre-existing collection of Trigoniidae will be measured using geometric morphometric analysis in order to examine shell shape and structure. A second goal is to determine the suitability of landmark analysis when investigating existing digital collections of bivalves and potential application in resolving paleoecology. Digital image analysis has the potential to be a useful tool when performing preliminary investigations when many resources are available by digital collection access, and field collections have yet to be made. Images of Trigoniidae will be scanned and landmarks on the exterior and interior, including dentition, selected with respect to functional morphology. Results will also be complied with the known paleoecology of the members in order to determine a relationship, if any, between the evolution of morphometric shape, dentition and adaption to environments.