Arboreal theory orbital vision reduction in olfaction

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• Arboreal Theory – Orbital convergence/stereoscopic vision – Reduction in olfaction – Grasping hands and feet with nails • Angiosperm Radiation Theory – Grasping hands used to allow foraging of flowers and fruit – Stereoscopic vision came later • Carpolestes (58Ma) had grasping hands well before the evolution of orbital convergence • Visual predation theory is best supported by adaptations seen in other Plesiadapiformes Uplif of the Himalayas and the Tibetan Plateau • Began about 55 Ma • Asian monsoon systems were created by altered wind patterns • Initial release of CO2 which contributed to warm temperatures early in the Cenozoic • Weathering of uplifed crust contributed to global cooling following the Miocene monsoon: seasonal reversing wind that carries precipitation, caused by the larger amplitude of seasonal changes on land compared to ocean Adapids & Omomyids • Early primates looked like modern strepsirrhines and tarsiers – Adapids • Resemble early Strepsirrhines – Omomyids • Have some traits of early strepsirrhines as well as early tarsiers. • Represent earliest Haplorhines Earliest Anthropoids • Rich fossil locality at Fayum, Egypt spanning 3 million years on the Eocene/Oligocene boundary • First undisputed ancestors to platyrrhines (New World monkeys) and catarrhines (Old World monkeys + apes/humans) • More than 20 primate genera preserved here • Most famous Fayum fossil is Aegyptopithecus zeuxis (35-33Ma) Neogene Miocene (23.8 – 5.3 Ma) • African plate collides with Europe, enclosing the Mediterranean, ending Indian-Atlantic currents, allowing faunal interchange, at one point closing the Med off completely • Panama isthmus closes, allowing faunal interchange; Gulf Stream forms, isolates Pacific from Atlantic • Iclandic ridge lowers, allowing Arctic water into Atlantic; Greenland ice sheet forms • East African uplif and rifing, leads to cooling and drying of region • Adaptive radiation of hominoids (apes) including as many as 100 species throughout Africa, Asia, and Europe • The evolution of the first probable hominins (Hominins: All the members of our clade AFTER the chimp-human split) • Overall cooling and drying of climate “Age of the Apes” global temperature drop at the end Pliocene (5.3 – 2.6 Ma) • Tectonic activity occurring during the Miocene continues; continents move into current locations • Arctic ice cap forms • Climate still warmer than today during at least the first half of the epoch – Decrease in CO2 at end of epoch helps cooling trend • Onset of Plio-Pleistocene ice age/glaciation starts ~2.8ma • Appearance of the first members of undisputed hominins • First appearance of Homo • Africa becomes dominated by ungulates • Herbivores increase in size • Tropical fauna begin to die out in Europe • First stone tools appear!
Rifing • Mantle plume causes doming of the crust • Subsequent erosion reduces weight of the crust above the plume • Heat and magma make the crust brittle and volcanism occurs • Down faulting of the crust forms rif Formation of the East African Rif Valley

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