Dating 1.Radioactive Half-Lifes 2.Index Fossils 3.Tree Rings 4.Genetic

Earth’s Timeline

Life Form Microbial (prokaryotic cells)3.8 Billion Complex (eukaryotic cells)2 Billion First multicellular animals1 Billion Vertebrates (simple fishes)500,000,000 Amphibians350,000,000 Reptiles310,000,000 Mammals200,000,000 Nonhuman primates60,000,000 Earliest apes25,000,000 Bipedal Hominids6,000,000 Modern human Ancestors 200,000 Dates of Life

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- Half Life

1.Potassium-40 found in your body at all times; half-life = 1.3 billion years 2.Uranium-235; half-life = 704 million years 3.Uranium-238; half-life = 4.5 billion years 4.Thorium-232; half-life = 14 billion years 5.Rubidium-87; half-life = 49 billion years Carbon-14 good for plant or animal life or things made from them but not sea life. 1- Carbon 14

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 2 - Index Fossils

3 - Tree Ring Dating

Genetic Dating/Clocks A technique 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.