The Death Pose
When found, many dinosaur fossils display a strange pose: Their necks are bent dramatically backward. Seeing this position, early dinosaur experts concluded that the animals could hold their necks this way in life. But it seems more likely that the pose reflects something that happened after the animal died.
A cord of springy tissue rather like a rubber band helps support the necks of most animals. This band, or ligament, can stretch to nearly twice its length when the neck is extended; it relaxes when the neck is in the neutral state. After an animal dies, the neck muscles slacken, the ligament shrinks and the neck straightens or bends back on itself.
Shrinking ligaments have led to some mistaken fossil reconstructions. The sauropod Diplodocus, for example, has often been shown with its head held high, like a giraffe. Scientists now know this was the death pose, not a life pose.
Bending Over Backwards
Some animals can do amazing things with their necks. Because the joint surfaces that let the bones glide over one another--the zygopophyses--are very long in camel neckbones, the animal can touch its head to its back with no risk that its neck vertebrae will slide too far and become dislocated. In sauropods, the zygopophyses are much shorter. A sauropod that tried this move would have dislocated its neck.