The role of the neck in the feeding behaviour of the Tyrannosauridae: inference based on kinematics and muscle function of extant avians

Tyrannosaurid necks were strong and powerful instruments for wielding the jaws during feeding. Hypotheses of tyrannosaurid neck function are here grounded by observations of neck morphology and function in extant archosaurs. Respectively derived morphologies in birds, crocodilians and tyrannosaurids compromise inferences for some muscles. However, alternate reconstructions indicate that tyrannosaurid neck muscles combined the robustness of crocodilian musculature with the functional regionalization seen in birds. Alternate hypothesized attachments of an avian-style muscle, the M. complexus, indicate different capacities for head dorsiflexion and lateroflexion. Electromyography of the M. complexus in chickens strengthens inferences about its function in both dorsiflexion and lateroflexion in extinct dinosaurs, and further suggests that it imparted roll about the longitudinal axis in concert with the actions of contralateral ventroflexors. Videography of extant raptors reveals the involvement of the neck when striking at prey and tearing flesh, and reconstructed tyrannosaurid musculature indicates capacity for similar neck function during the feeding cycle. As for birds, muscles originating in the anterior region of the neck likely stabilized the head by isometric or eccentric contraction as tyrannosaurids (and other large theropods) tore flesh by rearing back the body through extension of their hind limbs.