The Evolution of the Primate Prehensile Tail

The evolution of the prehensile tail illustrates the impact habitat can have on structural traits. Prehensile primates are able to support their entire body weight using only their tail, which opens up new feeding opportunities in their arboreal environments. This trait evolved separately in two families of New World monkeys. A transitional behaviour in its proposed evolutionary mechanism is tail-assisted hind limb suspension during locomotion in these dense forests. The evolution of more robust vertebrae, shorter distal vertebrae, a greater number of zygapophyseal joints, as well as larger and more convex articular surfaces, result in a stronger and more flexible tail. Prehensile tails have more expanded muscle attachments that can bear greater loading forces. A naked tactile pad that improves grip is present only in atelids. These differences in bone and muscle morphology make the prehensile tail more sturdy and dexterous, allowing prehensile primates to use their tails for an alternative function.