Figure 1.
Examples of Howler Monkey Vocalizations and Vocal Apparatus
(A and B) Group chorus of (A) unimale Venezuelan red howler monkeys, Alouatta seniculus (copyright Carolyn M. Crockett), and (B) multimale-multifemale black and gold howler monkeys, Alouatta caraya (black, males; gold, females; copyright Mariana Raño).
(C) Computed tomography (CT) surface model of adult male Alouatta sara showing highly modified vocal tract (left mandible removed from image).
(D) Schematic representation of the CT model. Red, hyoid; green, larynx; pink, tongue; dark gray, air sacs; brown, palate.