However, there is surprisingly littlediversity in the morphology of the vertebrae and myomeres alongthe long axis of the fish body (the trunk and peduncle, specifically)as compared to the morphology of the caudal fin skeleton (includ-ing fin rays) and musculature. The more anterior axial skeletal andmuscular anatomy is far more similar among living and extinctfishes than is tail fin morphology. This raises the question: why arefish tail fins so diverse, while trunk morphology is comparativelynot?