a201-11f-21-ApesEarlyHominins - Introduction to Biological...

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Introduction to Biological Anthropology: Notes 21 Apes and early hominins Copyright Bruce Owen 2011 - the first known hominoids (apes) appeared in the late Oligocene, 27 mya - example Oligocene ape : genus Proconsul (probably various species) - lived in tropical rainforest - fairly large, like a macaque - 33-110 pounds - hominoid traits - no tail - larger body size - slightly larger brain to body size ratio - short forelimbs and narrow chest indicate they were quadrupedal, walking on top of branches, as many monkeys do - rather than hanging by arms, as modern apes do - teeth indicate frugivorous diet - sturdy canines - procumbent incisors - thin enamel on the molars: relatively soft foods - Y-5 molars create a broad pulverizing surface, rather than the pointy piercing or saw- toothed shredding surfaces useful for other diets - another Oligocene hominoid: Morotopithecus bishopi - similar to Proconsul , but with hints of more apelike posture and locomotion - evidence: scapula (shoulder blade) suggests that it climbed and hung from branches, maybe brachiated - these are traits that became common in later apes - Hominoid radiation in the Miocene: the middle Miocene (15-10 mya) saw a great radiation of hominoids (apes) - that is, the hominoids split into many different lines, with different species adapting to many different niches - why? We don’t really know, but: - lots of climate changes in the Miocene - from the middle Miocene on, it got cooler and drier - tropical forests shrank, and there were greater areas of open woodland and savanna - the climate also began to change back and forth between warmer and cooler more rapidly, on a scale of just tens of thousands of years - this is too rapid to show in the general temperature chart in the slide - maybe these rapid changes, rather than the climate itself, was the key - maybe something about apes made them well suited to handle changing environments - maybe the ability to get by on a range of different foods, rather than being strongly committed to just one category of foods - also, Africa and Eurasia got close and joined, cutting off the Tethys sea around 15-10 mya - leading to an exchange of animals and plants
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Intro to Biological Anthro F 2011 / Owen: Apes and early hominins p. 2 - probably changing the ecology in many ways - and allowing some species of early apes (genus Proconsul ) to spread out of Africa to more varied environments - so populations of apes in different environments, surrounded by new varieties of plants and animals, evolved into many different species of apes - most of which went extinct by the end of the Miocene or slightly later
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This note was uploaded on 03/02/2012 for the course ANTHRO 201.3 taught by Professor Owen during the Fall '11 term at Sonoma.

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a201-11f-21-ApesEarlyHominins - Introduction to Biological...

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