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Giant monkeys are reported from many places in the world. Most sightings sound like normal monkeys, except that they are way too big. Reports of giant baboons come from Africa and India, similar to fossil finds of a baboon that is supposed to be extinct. South America has at least two reported varieties of giant monkey. One is similar to the howler monkey, except that it is gigantic.
The other South American giant monkey is often thought to be part of the great ape family, which includes chimps and gorillas and is not supposed to have any South American representative. This other giant monkey of South America is called the mono grande. It is reported to be about five feet tall, with a gracile build similar to a creature between an orangutan and a gibbon. Photographic evidence exists that exhibits features that would be difficult to fake.
However, recent evidence indicates that the mono grande is mixed up in a racist plot, and might have been faked for the purpose of claiming that each of the major races of humans descended from a different ape ancestor. This alleged hoax centers on a giant monkey that is often called De Loy's Ape or Ameranthropoides loysi. It is possible to believe in the mono grande even if you think De Loy's Ape is a fake, since folklore and sightings of the mono grande existed both before and after the alleged hoax, continuing up to recent times. Today, believers tend to think that the mono grande is a giant spider monkey, not an ape.
In North America, there are many giant monkey sightings that describe a far more bizarre creature, sometimes called a "devil monkey." Looking a bit like werewolves, these creatures are generally described as having pointed ears, a baboon-like snout (baboon snouts look like dog muzzles), and long tails. These tails are frequently described as bushy, like a wolf's tail or fox's tail, and occasionally they are described as hairless, like a rat's tail. Devil monkeys often prefer to go on all fours, and when they do rise on their hind legs, they generally travel by long jumps in the manner of a kangaroo, instead of the usual hairy humanoid's bipedal stride. The hind feet may only have three toes, or only show that many in footprints, and the hind legs are heavily digitigrade, with a long, narrow foot.
Devil monkeys are aggressive towards dogs, and sometimes humans, and they often are carnivorous, blamed for killing livestock. Adults can be up to six feet tall, and youngsters are often mistaken for kangaroos at first glance. In fact, these reports are often confused with or meshed with both anamalous kangaroo sightings and skunk-ape sightings. Some of the weirder reports include animals that are dogs from the waist up, kangaroos from the waist down.
If you think these monkeys sound rather bizarre, you are not the first to conclude this. These creatures really have cryptozoologists scratching their heads. North America is not supposed to have any native apes, and even if it did, you would expect something more like napes, the chimp-like North American cryptids. For these reasons, speculations about what these creatures might be has gone off in all directions. Some think it might be an extinct form of giant baboon, others think it is clearly so bizarre that it is supernatural and therefore of no interest to cryptozoologists, and yet others favor the idea of a kangaroo, like the bondegezou turned out to be, even though North America is not supposed to have any native kangaroos either.
Creatures like the North American "devil monkey" are sometimes reported from other areas of the world, where they have local names. One example is the drekavac of Serbian folklore, a label that is applied to several radically different monsters. One kind of drekavac resembles a dog on its upper body, while having the lower parts of a kangaroo. It is supposed to have a wailing cry that is unsettling to hear.
Clark, Jerome and Coleman, Loren. Cryptozoology A-Z. New York: Simon & Schuster, 1999. Pages 88-90
Coleman, Loren. Mysterious America: The Revised Edition. New York: Paraview Press, 2001. Pages 160-162
Keel, John A. The Complete Guide to Mysterious Beings. New York: Doubleday, 1994. Page 122
Newton, Michael. Encyclopedia of Cryptozoology: A Global Guide to Hidden Animals and Their Pursuers. Jefferson, North Carolina: McFarland & Company, 2005.
Weidensaul, Scott. The Ghost with Trembling Wings: Science, Wishful Thinking and the Search for Lost Species. New York: North Point Press, 2002. Page 175
Wikipedia, The. Ameranthropoides loysi
Wikipedia, The. Mono Grande