Lab 8 - Primate Evolution.docx - Name Tatyana Kim Section...

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Name: Tatyana KimSection: 03D9ANT 3514C – Introduction to Biological AnthropologyLab 8: Primate EvolutionSummer A 2018Lab Objectives:Examine the fossil evidence uniting and separating stem primates from crown primatesIdentify traits that support the inclusion of fossil primates within major cladesAssess the functional implications of the mosaic of traits found in early fossil apesProduce a brief behavioral summary of an extant primate from observationPurpose:To gain an overview of the primate fossil record from the Paleocene – Miocene.Understanding the origins of any group of animals is difficult. While evolutionary theory offers a strong foundation for howthis process occurs, our visible evidence is limited to the fossil record,which is only a small representation of past life. Though trillions of individual animals have lived during Earth’s history, much less than 1% ever become fossils, less than 1% of those fossils survive tectonics, volcanism, and erosion, and less than 1% of those will be found and studied by people. Our full understanding of evolution is limited by this incompleteness of the record.Most theories about how animals originate are adaptiveexplanations. For instance, primates have grasping hands and feet, a high reliance on vision compared to many other mammals, andnails instead of claws. But which of these traits appear in the last common ancestor (LCA) of all living primates? Knowing this information would allow us to test our hypotheses about which adaptations allowed early primates to flourish. Anthropologists interested in the question of primate origins often study “stem” primates. Stem taxa are extinct groups not directly ancestral to a living clade (also known as the “crown”), but that share a close common ancestor with the ancestorof the crown. Investigating the traitsof stem primates can help us determine the traits of the LCA of living primates, even without recovering its fossilized remains.Hominoidea includes modern humans, chimpanzees, bonobos, gorillas, orangutans, gibbons, and all of their extinct relatives since their divergence with old world monkeys. Modern apes are much less diverse and have a smaller geographic distribution (other than humans) compared to old world monkeys. However, the fossil record of the Miocene epoch reveals that apes were once extremely diverse and distributed throughout much of Africa, Europe, and Asia. All modern apes use below-branch suspensory locomotion in the trees, and the human shoulder girdle shares many features with other apes indicating a suspensory past. Parsimonysuggests that the last common ancestor of all modern apes must have been suspensory as well. However, theEarly Miocene ape fossil record subverts this expectation, suggesting instead that the locomotorbehaviors of modern apes were achieved independently in several different groups.

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