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Explore the Earth's timeline through dating methods like Carbon-14 and Genetic Clocks, tracing life forms from microbes to modern humans. Discover how Radioactive Half-Lifes, Index Fossils, Tree Rings, and Genetic Dating unveil the history of life on Earth.
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Dating Radioactive Half-Lifes Index Fossils Tree Rings Genetic
Dates of Life Life Form Microbial (prokaryotic cells) 3.8 Billion Complex (eukaryotic cells) 2 Billion First multicellular animals 1 Billion Vertebrates (simple fishes) 500,000,000 Amphibians 350,000,000 Reptiles 310,000,000 Mammals 200,000,000 Nonhuman primates 60,000,000 Earliest apes 25,000,000 Bipedal Hominids 6,000,000 Modern human Ancestors 200,000
1- Carbon 14 Compares ratio of carbon 14 to carbon 12 Good for up to 60K years Has a half-life of 5730 years & we can date 8-9 half-lifes where 1% of the original C-14 remains. At any given moment all living plants and animals have approximately the same percentage of carbon-14 in their bodies. After death carbon-14 decays but carbon-12 does not – so the ratio changes
1- Carbon 14 Potassium-40 found in your body at all times; half-life = 1.3 billion years Uranium-235; half-life = 704 million years Uranium-238; half-life = 4.5 billion years Thorium-232; half-life = 14 billion years Rubidium-87; half-life = 49 billion years Carbon-14 good for plant or animal life or things made from them but not sea life.
2 - Index Fossils A common fossil known to have lived in a particular geologic age for a relatively short period of time that can be used to date the rock layer in which it is found – Relative Dating
Genetic Dating/Clocks • Atechnique in molecular evolution used to measure the time of divergence of two species from a related ancestor. The length of time is calculated by measuring the number of molecular differences measured between the species' DNA sequences.