The evolutionary tree for vertebrates begins with the development of the vertebral column and braincase. The vertebral column, or "backbone," forms a segmented, incompressible anchor for muscles along the body, as well as protection for the central nerve cord. There is a distinct head region with a braincase, or cranium, that surrounds the brain, sensory structures, and cranial nerves. This point represents the beginning of your journey through vertebrate evolution.