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Paleobiology and Macroevolution Ch. 22.1-22.5

Paleobiology and Macroevolution Ch. 22.1-22.5. Geological Timeline . Precambrian Paleozoic Mesozoic Cenozoic. Mapping Out The Past. Several Methods: Carbon-14 Dating (living material) K-40 Dating (Certain soil types) Relative dating through strata layers

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Paleobiology and Macroevolution Ch. 22.1-22.5

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  1. Paleobiology and MacroevolutionCh. 22.1-22.5

  2. Geological Timeline Precambrian Paleozoic Mesozoic Cenozoic

  3. Mapping Out The Past • Several Methods: • Carbon-14 Dating (living material) • K-40 Dating (Certain soil types) • Relative dating through strata layers • Trace fossils foot tracks show migration; poop shows available food • Casts, molds, and petrified fossils

  4. The Ever Changing Earth • Gradual Factors: • Continental Drift tectonic plates constantly shift and collide • Climate change heating and cooling cycles influenced by atmosphere changes/sun spots • Glaciers and Sea Levels change geography and marine habitats • Sudden Factors: • Earthquakes caused by shifts in plates • Volcanos change geography and lower global temps. • Celestial Impacts Meteors and asteroids; change geography and lower global temps.

  5. Global Distribution • Shifting continents explain distribution patterns of similar species • Continuous Distribution live any where there is a suitable environment; seagulls live along all northern hemisphere coastlines • Disjunct Distribution similar species spread all over the Earth • Dispersal movement from original environment • Vicariance fragmentation by geographic factors • Southern Beech trees • only found on southern continents • Appear on Gondwana (early super continent) and spread before it fell apart too

  6. Biogeographical Realms • Formation of continents allowed for the creation of biogeographical realms where in biotas formed (all organism in a region) • Endemic species found only in one specific realm • Mammals of Australia mostly endemic marsupials • Unique because most other continents were connected by land bridges • Sometimes species on different continents with no common ancestor have identical phenotypes. How? • Convergent evolution species in similar environments evolve the same adaptations • Cactus morphology is the same everywhere

  7. Biodiversity • The amount of variation for all living things on Earth • Adaptive Radiation rapid speciation of related populations living in different environments; Darwin’s Finches • Adaptive zones new areas for the species to expand into • Major adaptations often lead to excess to new areas • Eggs shells reptiles have full land life cycle • Thicker fur allows mammals to move to colder areas

  8. Biodiversity • The amount of variation for all living things on Earth 2) Extinctions death of all members of one species • Lower diversity by removing species • Raise diversity by allowing new top species the resources to expand • Dinosaurs dying out allowed mammals to take over the Earth • Background Extinction Rate normal lose of species that do not adapt to gradual environmental changes • Mass Extinctions many species die out in a short about of time • Often caused by fast climate changes • 5 have occurred and 6th may be happening now with Greenhouse Gases

  9. The Big Five • Ordovician extinction: • 60% of life gone • Devonian Extinction: • Hostile environmental changes • Permian extinction: • Worst; 85% of life gone • Volcanic activity caused “runaway greenhouse” effect; rapid temp. change • Triassic extinction: • 50% of marine life and 80% of terrestrial quadrupeds gone • Cretaceous extinction: • 50% of life gone; dinosaurs • 10km diameter asteroid impact; dust clouded covered and cooled the Earth

  10. Changes in Fossils • As species adapt and speciation occurs, changes in fossils can tell us about the environment they are adapting too • Horses bodies grew in size; better structures for running; better teeth for tougher plant life…what could these tell us? • Body size smaller size is not favored; perhaps increase in predator size or numbers • Legs environment is more open; change in predator’s ability to run as well • Teeth change in climate/environment made smaller tougher plants selected

  11. Types of Evolution • The 100s of extinct species of horses all of the world support a slow shift in characteristics as they evolved • Phyletic gradualism hypothesis small gradual changes over long stretches of time • Most fossil records are too incomplete to support this • Punctuated equilibrium hypothesis changes come quickly as isolated populations adapt to their environments, then long periods of steady growth till another shift occurs

  12. Problems with Time • The vast amount of time life has existed on Earth is plenty to support the gradual hypothesis • Fossils are “snapshots” of a species separated by thousands of years, where generations of small changes could have occurred • Alternating periods of directional selection would make a species seem unchanged • Small body size is favorable over 500 generations, but then a change favors larger body sizes for the next 500 generations • Fossils of body before the small selection and after the large selection would be the same

  13. Homework • Suggested Homework: • Test Your Knowledge • Do not do #6 and #10 • Actual Homework: • Discuss the Concepts #1 • Design the Experiment • Interpret the Data

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