Vertebrae were the numerous individual bones that made up the backbone (vertebral column) of the dinosaur. Each individual vertebra was a roughly cylindrical-shaped piece of bone (centrum); on top of the vertebrae were neural arches, triangular arches of bone covering the spinal cord. The spinal cord in a dinosaur would run between the centrum and neural arch. A bony neural spine projected up from the neural arch and was where the back muscles were attached. Some dinosaurs, in addition to these basic features, had very complex vertebrae with all sorts of ridges and projections.

Each segment along the backbone had vertebrae that were specifically shaped to help that segment function. For example, the hip (sacral) vertebrae were fused together in dinosaurs in a structure called a sacrum; this provided support and strength for the hips. The neck (cervical) vertebrae were specifically shaped to provide flexibility, allowing the dinosaur to move its head around freely.

It’s impossible to pinpoint how many vertebrae each dinosaur had, as they varied greatly among all groups. In general, the neck bones held 9 to 19 vertebrae, the back had 15 to 17 of these bones, the hips held 3 to 10 vertebrae, and the tail had from 35 to 82 vertebrae, depending on the dinosaur.