Classification of Primates I - Prosimians/ lower primates include lemurs, lorises and tarsiers.Anthropoids, or higher primates include monkeys, apes, and humans. Prosimians; Generally small, arboreal, large, forwardly direct eyes. This is a small group of species, they tend to be between the size of a mouse and a house cat. Anthropoids; Stereoscopic and colour vision, Range of ecological niches, and improved manual dexterity. Classification of Primates IIStrepsirrhines, basal primates include lemurs, lorises and galagos.Haplorrhines, ‘higher’ primates include tarsiers and anthropoids. Strepsirrhines; Large eyes and ears, nocturnal, and Olfactory reliance. This is the ‘base group’.Haplorrhines; Reduced snout, large brain, more expressive facial features and have flatter faces, and Diurnal. (Phylogenetic relationships between anthropoids, tarsiers and lemurs/lorises share the tree.)Anthropoids Superfamilies Cercopithecoidea, catarrhinesOld World monkeys (ie. baboons, macaques)Ceboidea, platyrrhinesNew World Monkeys (ie. Howlers, marmosets)Hominoidea, catarrhinesApes (ie. Chimps)Oligocene 34-23 myaGlobal temperature crash and Environment of rivers with crocodile, elephant, and rhinoceros ancestors. Tropical and subtropical are now changing to mixed forest and being forced to adapt to new environmental dynamics. By the end of this era there is a split from the new world. Early history of AnthropoidsFayum District, Egypt has about 20,000 species of primates in this area. Lot’s of excavations have been done through the years to find fossils, such as the ‘Aegyptopithecus zeuxis’ that ate fruits. This lived a boreal life and was a possible ancestor to monkeys, it is also part of the basal group.Primates IIArboreal Hypothesis Collins 1921, szalay 1972. Collins began an idea of “we know primates start in the trees” and questioned why they need to stay in the trees and how did the evolutionize to adapt to life in the trees. Visual Predation Hypothesis Cartmill 1972, 1992, As a way for primates to actually get their prey at the tips of their branches. Not only primates were in the trees, and there were animals that were built for the trees. These species in the trees had the claws and the body structure to eat the small insects in the trees. Angiosperm-primate Coevolution HypothesisSussman 1991, hypothesised how primates evolved at the same time as angiosperms aka trees that carried and grew flowers and fruit. This is a diet based hypothesis, they used this to help determine the evolution to animals that lived in trees and what they ate and how they supplemented their diet. The animals ate the fruit from the trees and when the insects followed the sweet nectar from the fruit the species would also eat the insects in order to get all the nutrients needed. Comparative Anatomy of Primate LocomotionLocomotion; dependent on environment for reason of moving, possible predators. Mode of locomotion; most frequent way that a species moves, your entire skeletal structure is dependent on movement. Fore- and Hindlimb DifferencesForelimbThe shoulder girdleThe upper armThe lower armHindlimbThe pelvic girdle The upper legThe lower legHow can we predict locomotion?Intermembral index = Length of forelimb/ Length of hindlimb x 100The Intermembral Index Terrestrial Quadruped = 95-100Arboreal Quadruped = ~85 Clingers/Leapers = <80Brachiator/Suspensory = >120 Biped = ~72Vertical Clinging and Leaping Usually ProsimianIncludes lemurs, lorises and TarsiformsCrouched and clinging to a limbThigh muscles provide the force to produce a leapLand feet firstArms are mainly used for balance and stabilisationQuadrupedalism does not simply mean that a primate moves with hands and feet.Arboreal Quadrupedalism Includes: langurs, howler monkeys and Guenons. They have very long digits so that they can grasp tree branches, small body size and arboreal habitats and have a harder time adapting to new changes. Terrestrial Quadrupedalism Includes: Baboons, Macaques, they are not in the trees so their arms are not the same, they are mainly on the ground. Brachiation Includes: Gibbons and Siamangs, they have grasping feet and allows primates to maximise their food consumption. The Bipedal AdaptationAdvantages of bipedalism:Freed up the handsWider field of view ‘Efficient for distances Major features of Hominid Bipedalism Foramen Magnum (Spine and Pelvis)Leg Bone and Muscles (Knee and Feet)Hominid FootprintsPreserved in volcanic ash at Laetoli, Tanzania. Discovered in 1978 by Mark Leakey, Bipedal walkers at 3.5 mya. This shows that a type of bipedalism was present but not homo. Early Hominis II5 Adaptive RadiationFirst adaptive Radiation: 7-6 mya in the late Miocene, potential LCAsSecond Adaptive Radiation: 5-4 mya in early Pliocene, first true hominidsThird Adaptive Radiation: 4-3 mya in middle Pliocene, more hominids 1- Sahelanthropus tchadensis 7-6 mya in Chad (North Central Africa)2- Orrorin Tungenesis 6 mya in Kenya (East Africa) 1- Ardipithecus Kadabba and A. Ramidus5.8-4.2 mya in Ethiopia (East Africa)2- Australopithecus Anamensis 4.2-3.8 mya in Kenya (East Africa) 1- Australopithecus afarensis 3.7-3.0 mya in East Africa 2- Australopithecus africanus 3.3-2.1 mya in Southern Africa 3- Kenyanthropus/ Australopithecus platyops3.5-3.2 mya in Kenya