The smallest true primate (excluding tree shrews, which are normally classified separately) is the pygmy mouse lemur, or Peters' mouse lemur, which was discovered in the deciduous forests of western Madagascar. It has a head-body length of about 2.4 in ( 62 mm), a tail length of 5.4 in (136 mm), and an average weight of 1.1 oz (30.6 g).

Pygmy tarsiers' head-body length is from 3.7 to 4.1 in (95 to 105 mm), a tail length ranges from 5.3 to 10.8 in (135 to 275 mm). They weigh about 2 ounces (57 g). Pygmy tarsiers are found in central Sulawesi, Indonesia.

Pygmy marmosets have head-body length ranges from 4.6 to 6.0 in (117 to 152 mm), and a tail from 6.8 to 9.0 in (172 to 229 mm). The average adult body weight is just over 3.5 oz (100 grams). Pygmy marmosets are native to rainforests of the western Amazon Basin in South America.

Aye-ayes' size is: head and body from 14 to 17 in (355.6 to 431.8 mm), and tail from 22 to 24 in (558.8 to 609.6 mm). The average weight is 4 pounds (1.8 kg). They can be found only on the island of Madagascar.

More Info: www.guinnessworldrecords.com