Using the ‘comprehensive organism concept’, a holistic understanding of evolutionary processes is possible. Therein, the whole life of an organism - from fertilization to dead - is understood as a process of development on which selection can act through evolution. Heterochronies - changes in the developmental timing of characters - are hypothesized to have fundamental impact on shaping an adult structure. In mutual dependence with those, spatial reorganizations take place during development, so called heterotopies. Both mechanisms, together with allometric change, enable the evolution of new morphotypes.
With the help of standardized developmental characters, I study the patterns of embryonic timing in a variety of land vertebrate species, including turtles, snakes, lizards, and diverse mammalian groups. Given the recent advances in molecular systematics, a comprehensive (falcifiable) phylogenetic framework is provided, which I use to trace evolutionary developmental changes and discuss those in the context of morphological diversification. Besides organogenesis, also patterns of skeletogenesis and some genetic aspects of development and evolution are observed.
On a histological scale, development of particular organs is studied – a classic comparative embryological approach – in order to detect homologies, to uncover patterns of recapitulation, and to trace spatial developmental changes that lead to adult morphology. For adult anatomy, similar to my embryological studies, I concentrate on the craniocervical system of amniotes and some fish. One focus lies on the morphology of the musculature and other soft tissues, their anatomical diversity, phylogenetic distribution, and functional integration. Another focus lies on the interrelationship of head and neck morphology.
