According to the fossil record, from worm-like ancestors some 500 million years ago a group of animals evolved with a new kind of body, one with a bony internal backbone sporting an extended muscular tail. The animal group, of course, we now recognize as oour own -- vertebrates (from "vertebrate," the bones that make up the backbone). Less clear, however, is how the vertebrate body works and what difference its unique features have made to the evolutionary history of living fish, frogs, lizards, birds and mammals. These questions are the focus of a group of scientists gathering at the Annual Meeting of the Society for Integrative and Comparative Biology in Denver in early January, 1999. While all vertebrates have a backbone, which is evidence of their shared evolutionary history, all have different versions built, much like the various models of cars and trucks made for defferent driving conditions, for different kinds of support and movement in different environments. The backbone forms the framework for the body's axis, which also consits of muscles, skin, and nerves. This complex system of bone, ligaments, tendons and muscle generates bending motions that allow a fish to swim, a lizard to run, and a dolphin to leep. Bringing together scientists from fields in biomedicine, mathematics, and biology, the symposium, sponsored by the Society's Division of Vertebrate Morphology, plans to highlight many of the new findings in this scientific field. Presentations will focus on three areas -- the skeletal support system, locomotion, and the design of the axial systems in general. Axial systems in various model organisms will be discussed, including hagfish, bony fish, amphibians, reptiles and mammals.