Vertebra
Irregular bone, part of the core (axial) skeleton
Also known as: Backbone segment, spinal bone
Classification
Irregular bone, part of the core (axial) skeleton
Dimensions
Vary wildly from a few millimeters in small rodents to several inches across in large mammals, featuring a central rounded spool connected to various bony wings and a protective ring.
Key Features
Look for a solid central spool-like cylinder called the body, flanked by several wing-like extensions for muscle attachment and a central hollow ring through which the spinal cord passes.
Similar Bones
Can sometimes be confused with small hand or foot bones due to their compact size, but vertebrae are instantly distinguished by their central hollow channel and multiple projecting bony wings.
Across Species
In aquatic mammals like whales and dolphins, these bones lose many of their interlocking bony wings to allow high flexibility for swimming. In birds, many of these elements in the back fuse together to provide a rigid frame for powerful flight muscles, while the neck elements remain extremely flexible with a saddle-shaped joint.
Evolutionary History
These modular elements first appeared in early fish ancestors as a series of repeating segments surrounding and protecting the main nerve cord, eventually replacing the flexible rod of the notochord as the primary support structure for life on land.
Photography Tips
Place the bone on a neutral, solid surface with strong, angled side-lighting to cast shadows and highlight the intricate textures of the bony wings and the hollow central canal. Include a coin or ruler next to the bone for scale.