The phylum Chordata is a taxonomic group. All animals which have a  spine, or backbone, are classified in the phylum Chordata. There  are three subphylums in Chordata: Uroch â¦ ordata (tunicates),  Cephalachordata (lancelets), and Vertebrata (vertebrates).
The 12 vertebrae in the upper back make up what is known as the thoracic spine. They curve outward and inward to provide structure for the rib cage. The bones provide structure and flexibility for the body, while protecting the spinal colu... Read More.
The thoracic vertebrae are T1 - T12. The lumbar vertebrae are L1 - L5. The sacrum and coccyx do not have numbers and each is thought of as one bone. Spinal nerves exit the sacrum and coccyx at levels (Foramen) within the main structure of each vertebra.