Opisthotonic head displacement in the domestic chicken and its bearing on the…

The opisthotonic (‘dead bird’) posture encountered in non-avialan dinosaurs and other fossilized archosaurs is characterized by extreme dorsal neck retraction and tail protraction. Extant birds have been used to study this and attention has focused on the neck (because modern avians lack a long, freely articulated series of caudal vertebrae). The opisthotonic posture has been largely discus…