The spine or backbone is made of a long series of bones called the vertebrae. Each vertebra has a function and distinctive shape that separates it from the rest of the series. There are groups of vertebrae that are easily identified by the specific shape that reflects their collective work along the spine. For instance, the neckbones are called the cervical vertebrae and have distinctive shapes based on how they support the head. The ribcage is attached to the thoracic vertebrae, and encircles the thoracic region of the body. The lumbar vertebrae are the largest and bear most of the weight of the body. The sacral vertebrae are fused and are the point of attachment for the pelvic (hip) bones. The final tiny series of bones are the coccyx. Paleobiologists believe these are the remnants of a small tail.

The general structure of a vertebra consists of a...