Portal:Primates
The Primates Portal A primate is a member of the biological order Primates, the group that contains lemurs, the aye-aye, lorisids, galagos, tarsiers, monkeys, and apes, with the last category including great apes. With the exception of humans, who inhabit every continent on Earth, most primates live in tropical or subtropical regions of the Americas, Africa and Asia. Primates range in size from the 30-gram (1 oz) pygmy mouse lemur to the 200-kilogram (440 lb) mountain gorilla. According to fossil evidence, the primitive ancestors of primates may have existed in the late Cretaceous period around 65 mya (million years ago), and the oldest known primate is the Late Paleocene Plesiadapis, c. 55–58 mya. Molecular clock studies suggest that the primate branch may be even older, originating in the mid-Cretaceous period around 85 mya. Primates exhibit a wide range of characteristics. Some primates do not live primarily in trees, but all species possess adaptations for climbing trees. Locomotion techniques used include leaping from tree to tree, walking on two or four limbs, knuckle-walking, and swinging between branches of trees (known as brachiation). Primates are characterized by their large brains relative to other mammals. These features are most significant in monkeys and apes, and noticeably less so in lorises and lemurs. Many species are sexually dimorphic, which means males and females have different physical traits, including body mass, canine tooth size, and coloration.
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Despite their size, the giant lemurs shared many features with living lemurs, including rapid development, poor day vision, relatively small brains, and lack of male dominance. They also had many distinct traits among lemurs, including a tendency to rely on terrestrial locomotion, slow climbing, and suspension instead of leaping, as well as a greater dependence on leaf-eating and seed predation. The giant lemurs likely filled ecological niches now left vacant, particularly seed dispersal for plants with large seeds. There were three distinct families of giant lemur, including the Palaeopropithecidae (sloth lemurs), Megaladapidae (koala lemurs), and Archaeolemuridae (monkey lemurs). Two other types were more closely related and similar in appearance to living lemurs: the giant aye-aye and Pachylemur, a genus of "giant ruffed lemurs". Subfossil remains were first discovered on Madagascar in the 1860s, but giant lemur species were not formally described until the 1890s. The paleontological interest sparked by the initial discoveries resulted in an overabundance of new species names, the allocation of bones to the wrong species, and inaccurate reconstructions during the early 1900s. Discoveries waned during the mid-1900s, although paleontological work resumed in the 1980s and resulted in the discovery of new species and a new genus. The remains of the subfossil lemurs are relatively recent, with all or most species dating within the last 2,000 years. Humans first arrived on Madagascar around that time and likely played a role in the demise of the lemurs and the other megafauna that once existed on the large island. Although hunting and habitat change have been explored as the primary cause of their extinction, a mosaic of complex interactions between multiple factors is now seen as the ultimate cause of their disappearance. Yet oral traditions and recent sightings by Malagasy villagers are still reported, suggesting either lingering populations or very recent extinctions. Selected picture The white-fronted capuchin, Cebus albifrons, is a species of capuchin monkey, a type of New World primate, found in seven different countries in South America: Bolivia, Brazil, Colombia, Venezuela, Ecuador, Peru, and Trinidad and Tobago. The species is divided into several different subspecies, though the specific divisions are uncertain and controversial. CategoriesSelected species  Extinct (IUCN 3.1)|Extinct Afrasia djijidae is a fossil primate that lived in Myanmar approximately 37 million years ago, during the late middle Eocene. The only species in the genus Afrasia, it was a small primate, estimated to weigh around 100 grams (3.5 oz). Despite the significant geographic distance between them, Afrasia is thought to be closely related to Afrotarsius, an enigmatic fossil found in Libya and Egypt that dates to 38–39 million years ago. If this relationship is correct, it suggests that early simians (a related group or clade consisting of monkeys, apes, and humans) dispersed from Asia to Africa during the middle Eocene and would add further support to the hypothesis that the first simians evolved in Asia, not Africa. Neither Afrasia nor Afrotarsius, which together form the family Afrotarsiidae, is considered ancestral to living simians, but they are part of a side branch or stem group known as eosimiiforms. Afrasia is known from four isolated molar teeth (shown above) found in the Pondaung Formation of Myanmar. These teeth are similar to those of Afrotarsius and Eosimiidae, and differ only in details of the chewing surface. In the Pondaung Formation, Afrasia was part of a diverse primate community that also includes the eosimiid Bahinia and members of the families Amphipithecidae and Sivaladapidae. Did you know?
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