Primates have evolved over a period of millions of years, and the ultimate in evolution is the human. Over the course of time, different primates evolved different body structures which suited their time and their lifestyle, and the ecosystem into which they fit. The prosimians and the early primates were arboreal, and over time, they gradually descended from the trees, and developed an upright stance. This was accompanied by skeletal changes to accommodate the postural changes. Primates are distinguished from other mammals by nine general features:
1. A generalized limb structure, including basic pentadactyly and retention of bones often lost in other mammals (e.g. clavicle).
2. Mobile digits, especially the thumb and large toe.
3. Flattened nails and tactile pads occurring at the end of digits.
6. Less emphasis on the sense of smell.
7. Simple cusp pattern of molars and a general reduction in number of teeth.
8. Expanded and elaborated brain, especially the cerebral cortex.
9. Longer gestation and increased vascularization of placental membranes (Primates, 2004).
Primate evolution began in the Cenozoic era, with Lemuroids appearing in the Paleocene epoch, about 65 million years ago.
The major groups of primates come under the Order Primates, which divides into two suborders, the Suborder Strepsirhini (wet nostrils) and the Suborder Haplorhini (dry nostrils) (Haplorhine, 2004; Primates, 2004). Under the Suborder Strepsirhini comes the Infraorder Lemuriformes - the lemuroids. Under the Suborder Haplorhini come three Infraorders: the Infraorder Tarsiformes (tarsiers) the Infraorder Catarrhini, and the Infraorder Platyrhini.
Lemuriformes are found only in Madagascar (Primates, 2004). In the Superfamily Lemuroides, the Family Indriidae are unique in terms of locomotion in that they are vertical clingers and leapers, which emphasizes the hind limb's role in locomotion. Indris, the largest form of...