offspring although females giving birth to twins has been reported. Their gestation period is between 226 and 232 days long. Males have been observed engaging in infanticide. All victims of observed infanticide were from the same social group as their attackers and all were young males. Feeding The diet of White-bellied spider monkeys is 83% mature fruits and they are important to the seed dispersal of many fruit-bearing species. They carry a relatively high number of intact seeds in their gut and intake relatively large amounts of fruit pulp when compared to some other monkey species within their range. They also are likely to return to previous food sources and spend relatively little time foraging. A. belzebuth is a generalist frugivore that doesn't specialize in a particular fruit type but do appear to prefer fruits with high lipid content, high sugar content, or fruits produced by trees with high fruit productivity. They will also feed on other plant parts such as leaves, flowers, and bulbs, and will very rarely consume small insects. A. belzebuth has also been observed engaging in geophagy. Locomotion All members of Ateles are semi-brachiators, and this species has an intermembral index of 105. They have a fairly dorsally placed scapula to allow for increased mobility involved in brachiation. Their prehensile tail with a hairless gripping pad at the end also allows for this locomotion, which then means they have increased caudal vertebrae, with about 31 caudal vertebrae as opposed to another platyrrhine like Cebus with only 23 on average. This tail allows for additional grasping of branches, which means there is less lateral movement while brachiating which increases efficiency. The hairless gripping pad of the underside of the tip of their tail is often compared to a finger, since it allows surface gripping. Their curved hands with long metacarpal bones allows for easy brachiation. They do not have an external thumb, which sets them apart from most other primates. Dentition Ateles belzebuth has a dental formula of 2.1.3.3. As far as patterns within the teeth, there is a lot of variation but the following are often found within Ateles. Larger incisors and small molars reflect the largely frugivorous diet, with a diastema separating the upper canines from the upper incisors, for the lower incisor. The upper premolars have one to two cusps, with the first premolar having only one cusp, a paracone. The second premolar has