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Temporal range: Middle – Late Miocene
|An artist's illustration of Stirtonia|
Stirtonia is the first known howler monkey. It was a large primate for it's time.
Stirtonia had the most developed tail grab of all monkeys and a sharp head. It is believed that, like its modern relatives, could utter a deep, roaring sound to scare off rivals.
Today's howler monkeys mostly eat fruit. Its size is estimated to be around 1.1 metres long (3.6FT) and dating from the rocks where it was found in, was probably from the middle Miocene. Stirtonia's fossils were found in South America.