We are interested in explaining the uneven distribution of diversity across the tree of life. Why have some lineages of organisms experienced tremendous success in terms of morphological, functional, and ecological diversity, while other groups show little variation? We have a unique perspective on the analysis of macroevolutionary diversity patterns in that we combine phylogenetic inferences from living organisms with paleontological data across large temporal scales in order to gain a more integrative understanding of macroevolution. The dominant theme in our approach to unify quantitative paleobiology and phylogenetic comparative biology is functional morphology. Our work is founded on the idea that functional morphology is a key to a better understanding of the origins of diversity, because it establishes linkages between organismal structure and major niche dimensions. Thus, I organize my research around the identification of general mechanisms that explain how physical constraints and environmental opportunities interact with the design of specific functional systems to shape diversity. Some of the methods and techniques central to our research are functional morphology and optics, allometric analysis, multivariate statistics, and phylogenetic comparative methods, all in the framework of time-calibrated phylogenies.
Our primary study system is the vertebrate eye. We use functional analyses of eye morphology to guide the development of large comparative data sets in groups such as teleost fish, lizards, ichthyosaurs, dinosaurs, birds, and mammals. The visual system of vertebrates is a great system to test hypotheses about the origins of diversity, because the eye is a complex structure with multiple components, such as optics, photoreceptors, and ganglion cells, each with specific functional implications. As the physical requirements of vision are clearly defined, we can study morphological and functional adaptations to environments and behaviors that impose divergent physical challenges. The vertebrate eye offers a rich system for tests of hypotheses about the causes of diversity and is a key to a better understanding of the dynamics between physics and evolution.