Bite force, behavior, and electromyography in the teiid lizard, Tupinambis teguixin

We used electromyography (EMG) to investigate bite force production and feeding behavior in five individuals of the teiid lizard, Tupinambis teguixin. Three jaw adductor muscles were tested: pseudotemporalis superficialis (PST), adductor man dibulae externus superficialis (AMES) and pterygoideus (PTY). Force transducer tests determined that mean peak bite force in males (n = 3) was 70 N (22-105 N; n = 24). In females (n = 2), mean peak bite force was 60 N (14-00 N; n = 19). During high-intensity bites, the three muscles tested exhibited synchronous activation patterns, and these activities began before the onset of measured bite forces. Motor activities typically ceased at one-half of the total bite force duration. During natural feeding trials, initial capture bites and crushing bites exhibited motor activity patterns in all three muscles and were similar to those observed during high bite force development. In bites in which the lizards were picking up or moving prey, only the AMES exhibited motor activity. During prey processing, bites were observed that served to position the prey within the jaws and transport it to the esophagus. These bites were accompanied by activity in the AMES and PTY. In some cases, the latter bites were accompanied by activity in the PST. We concluded the AMES is active in all jaw closures. The PTY and PST are sequentially recruited to increase bite forces.