Do turtles have hollow bones

The spine is fused into the shell, with the ribs forming a major part of the inner portion of the shell. Uniquely, the shoulders are inside the rib cage formed by this process. The shell bones form growth plates that do not match the scute margins.

The spine through the neck bends in an 'S' curve, a vertical 'S' for Cryptodires - "hidey head" turtles, and a horizontal 'S' curve for Pleurodires - "sideneck" turtles.