tails are specialized to facilitate climbing and leaping in primates, and aids in other postures such as tail suspensions and foot hanging. With the features described, these primates can move through trees efficiently and obtain food easily. Body size also has a direct correlation to how fast and how far a primate can leap. There are other musculoskeletal specializations that differentiate VCL dependent primates, such as their hip joints and muscles. Leaping primates have more proximally positioned lesser and third trochanters, and have relatively large muscles for hip extensors, knee extensors or ankle plantar flexors. This is an adaptation that has come from the increased need for hind limb propulsion. The evolution of key features of VCL primate anatomy can be explained by analyzing how they leap. Longer limbs allow for enhanced locomotive abilities. Leaping requires primates to achieve a certain height and distance and then land on a vertical support. Longer hindlimbs therefore allow more time and distance for acceleration and takeoff, so longer and stronger femurs evolved because they increase the distance over which acceleration occurs. Additionally, during landing, longer limbs help with the deceleration of the body, since hindlimb length is directly proportional to the time required for landing. Therefore, longer limbs provide more time for deceleration and can prevent injury after landing with high velocity. Launch point considerations Launch point branch diameter Before leaping, primates must fundamentally consider the distance they are traveling and the stability in their launch point and landing point. A large branch is preferable to a small branch as a launch point, as the wider diameter provides a sturdier base for the jump and also reduces the energy expended during takeoff. In fact, tarsiers have been observed climb to lower heights in order to leap from and land on larger diameter branches. However, this also limits the height of the leap, as the primate must be able to land on a branch that is large enough to stabilize the animal and also minimize the energy necessary for maintaining balance during landing. Launch point angle Launch angle does not appear to be species-specific, and the range of angles varies between 30 and 70 degrees. The optimum ballistic trajectory angle would be 45 degrees, but often the animal will need to cover more horizontal than vertical distance, or vice versa. In these cases, a trajectory other than 45 degrees would be more beneficial to