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The vertebrae and ribs of dinosaurs are very different
from those found in humans. Dinosaur ribs do not meet at the sternum like ours
and have two connections to the vertebra. The vertebrae themselves vary tremendously
not only between different dinosaur species, but even between the vertebrae
of the neck, back and tail. Many have a bizarre system of processes and extensions
that interlock with other vertebrae in order to add strength and rigidity.
The Vertebrae
Centrum: The disk-like core of all vertebrae. In many dinosaurs the centrum can be extremely elongated and look like a tube more than a disk. To see a vertebra with a tube-like centrum click here. {top}
Zygapophysis: The process attached to the top of the centrum. It typically flares out into a pair of "wing-like" projections to which the ribs attach and can have a strong crest called the neural spine at the top. In caudal (tail) vertebrae the zygapophysis can be very reduced or absent.{top}
Diapophysis: The upper attachment point for the rib. Attaches to the tubercule of the rib. In many vertebrae the diapophysis and the parapophysis can be completely separate projections attached only at their base.{top}
Parapophysis: The lower attachment point for the rib. Attaches to the head of the capitulum of the rib. In many vertebrae the diapophysis and the parapophysis can be completely separate projections attached only at their base.{top}
Neural Spine: The crest at the top of the vertebrae. Some dinosaurs such as Spinosaurus had enromous extensions of the neural spines of the dorsal vertebrae that formed a "sail"-like structure.{top}
Neural Canal: The hole through which the nerve cord passes. Many people assume the nerve cord passes directly through the center of most vertebrae, but as you can see the disk-like centrum is actually solid bone!{top}
Dinosaur ribs vary widely in size and shape and can often be used as an identifying feature. Hadrosaurs and ceratopsians, for example differ in the shape of the head of the rib. In hadrosaurs the tubercule is small and slightly tapered, while the tubercule in ceratopsians (shown at the top of the page) is wide and nearly as large as the head of the capitulum. All dinosaur ribs attach at the diapophysis and parapophysis of the vertebra. In addition, dinosaurs have ribs in both the thoracic region as well as the cervical region and the change between the two determines which vertebrae are considered thoracic versus cervical.
Capitulum: The structure for attachment to the vertebrae that bends roughly 90 degrees away from the shaft of the rib. It attaches to the parapophysis.{top}
Tubercule: The structure for attachment to the vertebrae that sits at the end of the shaft of the rib. It always attaches to the diapophysis.{top}
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