are not unique to those animals. When comparing cetaceans to pinnipeds to sirenians, 133 parallel amino acid substitutions occur. Comparing and contrasting cetaceans-pinnipeds, cetaceans-sirenians, and pinnipeds-sirenians, 2,351, 7,684, and 2,579 substitutions occur, respectively. See also Hindlimb Anatomical terms of motion Bibliography References External links Evolution of chameleon locomotion: or how to become arboreal as a reptile Limbs (anatomy) Vertebrate anatomy Animal morphology