Primates: The Spider Monkey, Squirrel Monkey, Howler Monkey, and Golden Lion Tamarin – The Last Region of the World Colonized by Primates, the Continent With the Greatest Number of Monkey Species, the Number of Monkey Species Within the Jungles of South America, the Unique Physical Characteristic Evolved by Spider Monkeys, the Reason the Spider Monkey Tail Has Nerve Receptors, the Reason Spider Monkey Tails Have a Bare Patch of Skin at the Tip, the Monkey With the Strongest Tail, the Only Primate Species Without Thumbs, the Reason Spider Monkeys Evolved to Not Possess Thumbs, the Benefit of Tetradactyly (4 Digits/Fingers), the Reason Squirrel Monkey Digits Have Ridges Like Human Beings, the Reason Squirrel Monkeys Have Longer Legs Than Arms, the Loudest Mammal Call World Wide, the Intention of the Howler Monkey War Call, the Reason Howler Monkeys Can Produce a Low Baritone Call, the Evolution of Finger Nails for the Golden Lion Tamarin, the High Probability of Mammal Species Providing Birth to Twins, the Reason Golden Lion Tamarins Possess Bright Orange Fur, and the Number of Primate Species Which are Endangered During the Modern Day