However, tarsiers (small, nocturnal prosimian from the islands of the Southeast Asian archipelago) have characteristics of both groups. The older terms for the suborders that are still in popular use are Prosimii (see figure 2.3) and Anthropoidea. The primates are divided into two major taxonomic groups: strepsirrhines, which retain primitive characteristics, such as the lemurs of Madagascar and the bushbabies of Africa, and the more derived haplorrhines, that is, the tarsier, monkeys, and apes. Taxonomic charts of the living primates can be found below. Long pre- and post-natal life periods with greater reliance on learning. Prehensile (grasping) hands and feet and opposable thumb and big toe.Forward-oriented, overlapping fields ( binocular) of vision, and excellent depth perception.Enlarged visual cortex, greater visual acuity, and color vision.Reduction of snout and olfactory bulb in frontal cortex.Large, complex brain (relative to body size), especially cerebral cortex.Capable of varied movement and locomotion.Presence of a clavicle that allows greater mobility.No loss of limb bones from the ancestral condition.“ Mammal species pie chart” by Aranae is in the public domain. These trends were first proposed by Napier and Napier (1967) and Le Gros Clark (1959), and more recently primatologists have refined and added to the list. For example, prosimians retain a claw on the second digit of their feet, whereas anthropoids do not (more about the two primate groups later). However, we do not exhibit all of them to the same degree, and some are absent in certain species or lineages. Primates are distinguished by a suite of characteristics known as evolutionary trends (see table below). We are most closely related to tree shrews (order: Scandentia) and colugos (order: Dermoptera, also known as flying lemurs). The pie chart in Figure 2.2 shows the various orders of animals within the class Mammalia. We are primates, that is, members of the order Primates (prī-mā’-tēz).
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