Species: Aotus trivirgatus
Common name: Owl monkey
The Owl monkey lives in most of South America and is divided into many allopatric species.
The owl monkey is unique for several reasons, all related to vision. They are the only nocturnal anthropoid, although current thinking is that they evolved from diurnal species (because they have a retina with rods, cones, and a fovea). They differ from other nocturnal animals in that they have color vision. Because they are nocturnal their eye orbits are extremely large. They are medium sized monkeys with little to no sexual dimorphism. They have large digital pads and a grooming nail on the fourth digit of each foot. They are primarily fruit eaters but also eat leaves and insects. They live in monogamous families of 2-4 individuals – but unlike other monogamous monkeys, they rarely groom each other.
In the picture below you can see the size of the orbits.
In this picture you can see one of diagnostic features of platyrrhines, namely the lack of an ear tube…