Geometric morphometric character suites as phylogenetic data: extracting phylogenetic signal from gastropod shells

Despite being the objects of numerous macroevolutionary studies, many of the best-represented constituents of the fossil record—including diverse examples such as foraminifera, brachiopods, and mollusks—have mineralized skeletons with limited discrete characteristics, making morphological phylogenies difficult to construct. In contrast to their paucity of phylogenetic characters, the mineralized structures (tests and shells) of these fossil groups frequently have distinctive shapes that have long proved useful for their classification. The recent introduction of methodologies for including continuous data directly in a phylogenetic analysis has increased the number of available characters, making it possible to produce phylogenies based in whole or part on continuous character data collected from such taxa. Geometric morphometric methods provide tools for accurately characterizing shape variation and can produce quantitative data that can therefore now be included in a phylogenetic matr...