Anth 204 February 9.docx

Anth 204 February 9, 2010 Week 5 Primates- a group of mammals in the order of primates, includes prosimians, monkeys, apes and humans What makes a primate? Arboreal adaptation-life in trees Dietary plasticity-variety of foods Parental investment Skeleton Generally the same features in all primates Highly mobile joints and flexible limbs Have great flexibility for movement in trees (Clavicle, Ulnae and radius) Characteristics of Primates: Hands and Feet High degree of grasping ability 5 digits on both hands and feet Opposable thumb and partially opposable great toe Increase in Sense of Touch (grip) Tactile pads enriched with sensory nerve fibers at the ends of digits, (fingerprints)- resistance to slipping Nails instead of claws- important factor for gripping 5 functionally distinct vertebra Greater range of movement Dietary Plasticity Reduced number of teeth Due to order?s diverse diet non-specialized teeth throughout the order Characteristics of Primates: Diet and Teeth Lack of Dietary specializations Most omnivorous Generalized dentition, teeth are not specialized for processing on type of food Molar cusps Bilophodont (2 ridged) baboons Y-5 5 separate cusps (apes and humans) Canine-premolar homing complex The upper canines are sharpened against the lower premolars whrn the jaw is closed Important for slicing leaves and other plants Parental Investment- social Longer gestation, fewer offspring, delayed maturation, and longer life span Greater dependence on flexible, learned behavior Tendency to live in social groups Tendency for diurnal(live during the day) activity patterns Tooth comb Important aspect of grooming- Lemurs Brain Expansion of the neocortex-associated with sensory aspects of vision Expansion and increased complexity of brain Occipital love gets bigger while olfactory bulb gets smaller Increased Sense of Vision (isolate prey) Increased reliance on vision Medially rotated eyes (binocular vision) Color vision- diurnal Depth perceptions Stereoscopic vision (3D) Boney eye sockets-post orbital bar Decreased sense of smell and hearing Summary Generalized skeletal pattern Increased sense of touch ? brain size ? dietary versatility ? sense of vision Decreased sense of smell?.. Why? Arboreal theory In order to adapt to tree living they require grasping hands and feet, teeth for the variety of available foods in treed environments and for activity during the day (diurnal) Visual predation hypothesis Primates may have first developed on the ground and as they were snatching insects they evolved into tree dwelling species. Angiosperm radiation hypothesis Visual acuity, grasping hands and feet were adaptations for eating fruits and other available plants with flowers- angiosperms Theories All come to a similar conclusion that they were adaptations to the environment and available food resources Chicken and the egg Primate Origins Cenzoic (60 mya to present day Age of mammals Continents in modern placement Primates/ adaptive radiation of primates Primate origins in the placental mammal radiation 65 mya The earliest undoubted primates appear in the Eocene epoch Primate like ancestors but the fossil record is sparse. Prior to 55 mya Plesiapiforms are most likely the primate ancestor Carpolestes found in Wyoming Eocene (55 mya) Euprimates- first true primates Fragmentary remains No specifics Prosimian evolution and radiation Apaids Lemurs Omomyids Tarsiers Late Eocene Basil anthropoids (more modern to modern primates) Eosimias-(China 42 mya) Biretia- (Africa 37 mya) Fossil record is sparse and as a result difficult to determine our ancestor past 34 mya