Fossils contain isotopes that accumulated in the organisms when they were alive

Fossils contain isotopes that accumulated in the

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Fossils contain isotopes that accumulated in the organisms when they were alive The age of some fossils can be estimated by measuring the ratio of the radioactive isotope carbon-14 to the stable isotope carbon-12 Radiocarbon dating can be used to date fossils up to 75,000 years old
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The age of older fossils can be estimated by using isotopes with long half-lives to date volcanic rock layers above and below the fossil 5. List key events in geological history Key events in life’s history include the origins of unicellular and multicellular organisms and the colonization of land Part 2: 6. Describe how Pangea contributed to an increase in biodiversity Separation of landmasses can lead to allopatric speciation Large number of marsupials in Australia Old world vs new world monkeys 7. Describe how mass extinction event effect biodiversity The fossil record shows 90% of the species that have ever lived are now extinct Extinction can be caused by changes to a species’ biotic or abiotic environment At times, the rate of extinction has increased dramatically and caused a mass extinction It typically takes 5–10 million years for diversity to recover following a mass extinction; in some cases up to 100 million years Mass extinctions can change the types of organisms found in ecological communities The number of mammals increased after the cretaceous mass extinction. 8. Describe the effects of the Permian and Cretaceous mass extinctions 9. The Permian extinction defines the boundary between the Paleozoic and Mesozoic eras 252 million years ago This mass extinction occurred in less than 500,000 years and caused the extinction of about 96% of marine animal species A number of factors might have contributed to this mass extinction Extreme volcanism in what is now Siberia Global warming and ocean acidification resulting from the emission of large amounts of CO 2 from volcanoes
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Anoxic conditions resulting from nutrient enrichment of ecosystems The Cretaceous mass extinction occurred 66 million years ago More than half of all marine species, many families of terrestrial plants and animals, and all of the dinosaurs, except birds, went extinct during this event The presence of iridium in sedimentary rocks from that time period suggests a meteorite impact Dust clouds caused by the impact would have blocked sunlight and disturbed the global climate The Chicxulub crater off the coast of Mexico is evidence of a massive meteorite collision that dates to the same time 10. Explain adaptive radiation and give examples of when it might occur Adaptive radiation is the rapid evolution of diversely adapted species from a common ancestor Adaptive radiations may follow mass extinctions the evolution of novel characteristics the colonization of new regions 11. Explain how even complex structures can result from evolution Most novel biological structures evolve in many stages from previously existing structures Complex eyes have evolved from simple photosensitive cells independently many times 12.
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