Evolving the Concept of Homology

Understanding homology is fundamental to learning about evolution. The present study shows an exercise that can be varied in complexity, for which students compile research illustrating the fate of homologous fish skull elements, and assemble a mural to serve as a learning aid. The skull of the most primitive living Actinopterygian (bony fish), the bowfin, "Amia calva," is the starting point for tracing the evolutionary fate of homologous bones in other living and extinct vertebrates. By tracing bone fates through time and across lineages, students learn both their names and association patterns. Emphasizing bone group associations, structures and functions replaces memorization of names, while facilitating understanding of evolutionary processes that shaped complexes and the vertebrates in which they occur. Working in groups, students learn cranial ossification patterns from fish to amphibians, reptiles, mammals and birds that might otherwise seem unpredictable or unrelated to natural selection. Goals of this project include clarifying evolutionary processes, relating complex structures to functions, and assisting students in gaining a deeper understanding of features that define vertebrate anatomical relationships. (Contains 4 figures.)