Studies on the morphology and function of the skull in the boidae (Serpentes). Part II. Morphology and function of the jaw apparatus in <i>Python sebae</i> and <i>Python molurus</i>

TLDR

The study aimed to correlate head morphology with observed jaw movements to analyze functional and adaptive implications of the jaw apparatus. The authors dissected heads, examined arthrology, myology, and dentition, and used high‑speed and regular‑speed motion‑picture recordings to analyze cranial bone motions and mechanical factors during feeding. They found that the snake cranial apparatus functions as a loose kinematic chain, contrasting with the rigid lizard jaw, and that during full protraction the maxillae and palatines lift and rotate to orient teeth for seizing and swallowing prey.

Abstract

Abstract Heads of the boid snakes Python sebae and Python molurus were dissected and the arthrology, myology and dentition studied. Living specimens of these species were observed and their feeding behavior analyzed by means of high‐ and regular‐speed motion pictures. Camera speeds of up to 400 frames per second permitted examination of the jaw movements during the striking and seizing of prey. Motion picture studies conducted at regular speeds provided information on cranial movements during the swallowing of prey. The morphology of the head was correlated with observed movements in an attempt to analyze the functional and adaptive implications of the jaw apparatus. The cranial apparatus was discussed in terms of a linkage or kinematic chain whose constrainment and degrees of freedom were examined and compared with the jaw linkage of lizards. It was concluded that the very rigidly constrained mechanism in lizards is in remarkably sharp contrast to the very loose apparatus in snakes. Motions of various cranial bones were analyzed with particular attention given the mechanical factors involved. In full protraction the maxillae and palatines are lifted and rotated outward about a longitudinal axis. These movements are important in orienting the teeth with respect to the prey and are related to seizing and swallowing.