Anthrobio 364 Textbook Notes

Anthrobio 364 Textbook Notes - A nthrobio 364 Textbook...

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Anthrobio 364 Textbook Notes Chapter 4— Mammalian Antecedents “Big Bang” Theory - 15 billion years ago; 3 billion years ago, galaxies and solar systems were formed, 4.5 billion years ago earth was formed of gases in the atmosphere, amino acids from heat and lightning formed “organic soup, combined to form nucleic acid polymers Prokaryotes - early single-celled organisms (3.5 to 2.8 billion years ago); do not have nucleus or mitochondria, single thread of DNA; reproduced asexually, making copies of themselves; varied through mutation Eukaryotes - (1.5 billion years ago) organisms with cells with nuclei and mitochondria that divide by mitosis and meiosis; 570-510 million years ago, gave rise to multicellular organisms which reproduce sexually and in addition to mutation and fertilization, also provide genetic and phenotypic variation. Relative dating: 1. Stratigraphy- indicates whether a given specimen is older or younger than another one, depending on the location of the specimen 2. Fluorine Analysis- applies only to bone; uses the ratio between the amount of minerals absorbed in bones and the amount of nitrogen lost Absolute dating: 1. Uranium-238 Decay- one half of the original amount of U-238 is lost in 4.5 billion years and becomes lead; determine how much U-238 is in rock 2. Potassium-Argon- based upon the radioactive decay of potassium-40 which has a half-life of 1,250 years and produces argon-40. 3. Fission-track- evaluates minerals in a deposit, heavy isotopes decay and leave tracks, may be chemically heated and counted, the number of tracks is the age 4. Thermoluminescence- when crystals are heated, they give off a flash of hot light; the amount of light is proportional to the age of the material (50- 300,000 years ago) 5. Carbon-14- based upon the principle that one-half of the original amount of carbon present in any material is lost in 5,730 years (1,000- 45,000 years old) Paleozoic Era - (570 to 280 million years ago)- fish, amphibians, and reptiles appeared Mesozoic Era - (225 to 135 million years ago)- amphibians that descended from lobe-finned fishes transitioned to land. Reptiles made a complete adjustment to terrestrial life, increase in complexity of the egg. Key for the dinosaurs was evolution of the upright stance. Cenozoic Era - 65 million years ago dinosaurs became extinct. During Triassic period (225- 190 million years ago), reptile developed into mammal-like form—structural changes provided functional flexibility to exploit nutritional resources.
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- Central nervous system- larger brains, cerebrum is enlarged, especially the neocortex - Reproductive efficiency- mammals give birth to live young—viviparous - Dentition- mammals have heterodontic dentition; teeth vary greatly in size and shape, mammals masticate their food - Dental formula- one-half of the jaw is used, total human teeth= 32 - Temperature regulation- constant internal body temperature irrespective of changes in ambient temperatures; energy generated internally through
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This note was uploaded on 01/23/2011 for the course ANTHRBIO 364 taught by Professor Frisancho during the Winter '10 term at University of Michigan.

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Anthrobio 364 Textbook Notes - A nthrobio 364 Textbook...

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