chapter 19 the history of life. the fossil record palentologists study fossils palentologists study...
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The Fossil recordThe Fossil record
Palentologists study fossilsPalentologists study fossils These records provided evidence These records provided evidence
about the history of life on earthabout the history of life on earth It shows that different organisms It shows that different organisms
have changed over timehave changed over time Some even became extinctSome even became extinct
Interpreting Fossil EvidenceInterpreting Fossil Evidence
Relative dating- used to determine Relative dating- used to determine the age of a fossilthe age of a fossil
You compare the fossil’s placement You compare the fossil’s placement in the rock layer with other fossils in in the rock layer with other fossils in the rockthe rock
The rock layers are formed by age The rock layers are formed by age with the oldest on the bottomwith the oldest on the bottom
Index fossilIndex fossil
Can be used if the species is easily Can be used if the species is easily recognized and existed for a short recognized and existed for a short period but have a wide geographic period but have a wide geographic rangerange
Radioactive datingRadioactive dating
Scientists calculate the age of a Scientists calculate the age of a sample based ion the amount of sample based ion the amount of remaining radioactive isotopes it remaining radioactive isotopes it containscontains
The half life is the minimum amount The half life is the minimum amount of time it takes for half of a of time it takes for half of a radioactive element to decayradioactive element to decay
Geological time scaleGeological time scale
Used to divide timeUsed to divide time After precambrian time, the basic After precambrian time, the basic
divisions of the geological time scale divisions of the geological time scale are eras, periods, and epochsare eras, periods, and epochs
eraseras
Paleozoic era- 544 million years ago, Paleozoic era- 544 million years ago, vert and invertvert and invert
Mesozoic- 251 million yrs ago, dino Mesozoic- 251 million yrs ago, dino and mammalsand mammals
Cenozoic- 65 million yr ago, mammal Cenozoic- 65 million yr ago, mammal ageage
Periods and epochsPeriods and epochs
Period range in length from 10 Period range in length from 10 million years to less than 2 million million years to less than 2 million yearsyears
Further divide periods into epochsFurther divide periods into epochs
Earths Early HistoryEarths Early History
Formation of the earth occurred 8.2 Formation of the earth occurred 8.2 billion years agobillion years ago
Its early atmosphere contained Its early atmosphere contained hydrogen cyanide, carbon dioxide, hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, carbon monoxide, nitrogen, hydrogen sulfide, and waterhydrogen sulfide, and water
First organic moleculesFirst organic molecules
Miller and Urey did an experiment Miller and Urey did an experiment which suggested how mixture of which suggested how mixture of compounds could have arisen from compounds could have arisen from simplier compounds present on simplier compounds present on primitive earthprimitive earth
How Did Life begin?How Did Life begin?
1. formation of microspheres1. formation of microspheres 2. evolution of RNA and DNA2. evolution of RNA and DNA 3. free oxygen in air drove some life 3. free oxygen in air drove some life
forms to extinction and evolved forms to extinction and evolved othersothers
Origin of Eukaryotic CellsOrigin of Eukaryotic Cells
The endosymbiotic theory proposes The endosymbiotic theory proposes that eukaryotic cells arose from that eukaryotic cells arose from living communities formed by several living communities formed by several organismsorganisms
After eukaryotic cells arose, those After eukaryotic cells arose, those cells began to reproduce sexuallycells began to reproduce sexually
This enabled evolution to take place This enabled evolution to take place at a greater rateat a greater rate
Evolution of multicellualr life formsEvolution of multicellualr life forms
90% of Earth’s history occurred during 90% of Earth’s history occurred during PrecambrianPrecambrian
Simple anaerobic forms appeared and Simple anaerobic forms appeared and were followed by photosyntheitc forms were followed by photosyntheitc forms which added oxygen to the airwhich added oxygen to the air
Aerobic forms evolved and eukaryotes Aerobic forms evolved and eukaryotes appearedappeared
Early in Paleozoic era the fossil record Early in Paleozoic era the fossil record became rich with evidence of many types became rich with evidence of many types of marine lifeof marine life
Life was highly diverse by the first part of Life was highly diverse by the first part of Paleozoic eraPaleozoic era
Cambrian PeriodCambrian Period
This is when diversification of life This is when diversification of life occurredoccurred
Organisms had hard part and first Organisms had hard part and first animilia phyla evolvedanimilia phyla evolved
Trilobites were commonTrilobites were common
Ordovician and silurian periodsOrdovician and silurian periods
Octopus and squid ancestors Octopus and squid ancestors appeared along with aquatic appeared along with aquatic arthropodsarthropods
Devonian periodDevonian period
Animals began to invade the landAnimals began to invade the land Fish developed the ability to crawl on Fish developed the ability to crawl on
leglike finsleglike fins Fish had jaws, bony skeletons, and Fish had jaws, bony skeletons, and
scalesscales
Carboniferous and permian periodCarboniferous and permian period
Life expanded over the earth’s continentsLife expanded over the earth’s continents Other groups of vert evolved from Other groups of vert evolved from
amphibiansamphibians Mass extinction occurred at the end of the Mass extinction occurred at the end of the
Paleozoic eraPaleozoic era It affects both plants and animals on land It affects both plants and animals on land
and on seaand on sea 95% of the complex life in the ocean 95% of the complex life in the ocean
disappeareddisappeared
Mesozoic eraMesozoic era
Increase dominance of the dinosaursIncrease dominance of the dinosaurs 1. triassic period-fish, reptiles insects1. triassic period-fish, reptiles insects 2. jurassic period-dinosaurs dominant2. jurassic period-dinosaurs dominant 3. cretaceous period-reptiles still 3. cretaceous period-reptiles still
dominated, but another mass dominated, but another mass extinction occurredextinction occurred
Cenozoic eraCenozoic era
Mammals evolved adaptations that Mammals evolved adaptations that allowed them to live in various allowed them to live in various environmentsenvironments
Patterns of evolutionPatterns of evolution Macroevolution- large scale change that Macroevolution- large scale change that
take place over a long timetake place over a long time There are 6 important patterns to There are 6 important patterns to
macroevolution:macroevolution: 1. mass extinction1. mass extinction 2. adaptive radiation2. adaptive radiation 3. convergent evolution3. convergent evolution 4. coevolution4. coevolution 5. punctuated equilibrium5. punctuated equilibrium 6. changes in developmental genes6. changes in developmental genes
Adaptive radiationAdaptive radiation
Unrelated organisms come to Unrelated organisms come to resemble one anotherresemble one another
coevolutioncoevolution
The process by which 2 species The process by which 2 species evolve in response to changes in evolve in response to changes in each other over timeeach other over time
Ex flowering plantsEx flowering plants