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earth sc. ch. 9 FOSSILS: REMAINS OR EVIDENCE OF ANCIENT LIFE

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Presentation on theme: "earth sc. ch. 9 FOSSILS: REMAINS OR EVIDENCE OF ANCIENT LIFE"— Presentation transcript:

1 earth sc. ch. 9 FOSSILS: REMAINS OR EVIDENCE OF ANCIENT LIFE
REMAINS ARE PRESERVED WHEN BURIED BY SEDIMENTS QUICK BURIAL HELPS PRESERVATION SEDIMENTS PRESERVE HARD PARTS IN SEDIMENTARY ROCK COMMON ANIMAL REMAINS: BONES, SHELLS, TEETH COMMON PLANT REMAINS: POLLEN, SEEDS, STEMS PALEONTOLOGISTS: SCIENTISTS WHO STUDY FOSSILS slide 1

2 PETRIFIED: LIVING TISSUE TURNED INTO STONE
EIGHT TYPES OF FOSSILS PETRIFIED: LIVING TISSUE TURNED INTO STONE THE REMAINS ABSORBS WATER WITH DISSOLVED MINERALS TISSUE SLOWLY DECAYS, LEAVES MINERAL-HARDENED FOSSIL MOLD: HOLLOW IN SEDIMENTARY ROCK FORMED BY AN ORGANISM CAST: COPIES THE SHAPE OF AN ORGANISM WHEN MOLD IS FILLED IN 4. CARBON FILM: THIN LAYER OF CARBON FROM FOSSIL CARBON FROM CELLS LEFT AFTER DECAY CREATES IMPRESSION OF ORIGINAL LIVING slide 2

3 EIGHT TYPES OF FOSSILS (cont.)
5. TRACE FOSSIL: FOSSIL MADE BY OR LEFT BY ANCIENT LIFE INCLUDES FOOTPRINTS, NESTS, BURROWS, COPULITE COPULITE: FOSSILIZED ANIMAL DUNG 6. TAR PITS: WATER FILLED DEPRESSIONS OF PETROLEUM DEPOSITS ANIMALS COME TO DRINK, GET TRAPPED AND DIE TAR PRESERVES REMAINS OF ANIMALS, PLANTS AND INSECTS La Brea Tar Pits NEAR Los Angeles MOST WELL KNOWN EXAMPLE 7. AMBER: HARDENED TREE SAP WHICH TRAPS AND PRESERVES INSECTS 8. FREEZING: PRESERVES FLESH AND BONE IN PLACES SUCH AS ALASKA slide 3

4 FOSSIL RECORD AND EVOLUTION
SHOWS CHANGES IN LIFE, EARTH'S SURFACE OVER TIME INDICATES THAT FOSSILS CHANGED IN A SPECIFIC SEQUENCE LIFE FORMS DEVELOP FROM SIMPLE TO COMPLEX SUPPORTS THE THEORY OF EVOLUTION EVOLUTION: GRADUAL NATURAL PROCESS IN WHICH LIFE CHANGES ALLOWS ADAPTATIONS TO CHANGES IN CLIMATE, ENVIRONMENT EVOLUTION IS A SCIENTIFIC THEORY THEORY: AN UNPROVEN EXPLANATION BASED ON EVIDENCE slide 4

5 THE FOSSIL RECORD INDICATES 3 WAYS THE ENVIRONMENT HAS CHANGED
1. INDICATES THAT LIFE HAS CHANGED MILLIONS OF SPECIES OF LIFE HAVE BECOME EXTINCT, CHANGED SPECIES: LIFE FORM OF LIFE ABLE TO INTERBREED (PRODUCE YOUNG) SPECIES MAY BECOME TOO DIFFERENT TO INTERBREED OVER TIME 2. INDICATES THAT THE EARTH’S SURFACE HAS CHANGED CONTINENTS HAVE MOVED AND CHANGED MOUNTAIN RANGES, DESSERTS, VOLCANIC FEATURES FORM, DISAPPEAR 3. INDICATES CHANGES IN A LOCAL AND GLOBAL CLIMATES RAIN & TEMPERATURE PATTENS CHANGE THE ENVIRONMENT ANTARTICA ONCE A HOT, SWAMPY, RAIN FOREST slide 5

6 FINDING THE AGE OF FOSSILS
1. ABSOLUTE AGE: NUMBER OF YEARS OLD A FOSSIL BASED ON ITS ATOMS BASED ON THE ACTUAL MATERIAL OF THE FOSSIL RADIOACTIVE DATING IS OFTEN USED TO DETERMINE ABSOLUTE AGE 2. RELATIVE AGE: FOSSIL'S AGE RELATIVE TO ROCK LAYERS, OTHER FOSSILS AGE ESTIMATED BY THE AGE OF KNOW MATERAILS AROUND FOSSIL LAW OF SUPERPOSITION: STATES THAT TOP ROCK LAYERS ARE YOUNGER AND BOTTOM LAYERS ARE OLDER IN UNDISTURBED ROCK A LAW IS A REPEATED PROVEN THEORY ACCEPTED AS TRUE SEDIMENTARY ROCK FORMS LAYERS AS DEBRIS ACCUMULATES GRAND CANYON: OLDEST FOSSILS ARE AT BOTTOM OF CANYON slide 6

7 2. RELATIVE AGE (continued)
IGNEOUS ROCK FORMATIONS HELP FIND RELATIVE AGE ROCK EXTRUSIONS: YOUNGER THAN ROCK LAYERS THEY COVER ROCK INTRUSIONS: YOUNGER THAN THE ROCK THEY GO THROUGH FAULTS: YOUNGER THAN THE ROCK THEY GO THROUGH INDEX FOSSIL: COMPARISION TOP COMMON, WELL STUDIED FOSSILS FOSSIL ASSUMED THE SAME AGE AS THOSE FOUND WITH IT COMMON EXAMPLE : TRILOBITES UNCONFORMITY: GAP IN THE GEOLOGIC RECORD, OLDER ROCK ON TOP MAY BE CAUSED BY ROCK MOVEMENT, UPLIFTING MAY BE CAUSED BY EROSION OF SOFTER TOP LAYERS slide 7

8 RADIOACTIVE DATING: MEASURE OF THE LOSS OF RADIOACTIVE ENERGY
ALL MATTER IS MADE OF ATOMS ELEMENTS: MADE OF IDENTICAL ATOMS, 109 KNOW TO EXIST MOST ATOMS ARE STABLE (NORMALLY DO NOT CHANGE) FEW UNSTABLE, BREAKDOWN TO FORM OTHER ELEMENTS OVER TIME RADIOACTIVE DECAY: CHANGE OF UNSTABLE ELEMENTS TO STABLE ONES OCCURS AT THE SAME UNIQUE RATE FOR EACH UNSTABLE ELEMENT HALF-LIFE: TIME FOR 1/2 OF THE UNSTABLE ELEMENT TO CHANGE AN ELEMENT'S HALF-LIFE IS USED TO DETERMINE ITS ABSOLUTE AGE slide 8

9 OBTAINING ABSOLUTE AGE FROM RADIOACTIVE HALF-LIFE DATING
POTASSIUM 40 (UNSTABLE) TO ARGON (STABLE) HAS A HALF-LIFE OF 1.3 BILLION YEARS (DATES OLDEST ROCKS) CARBON 14 ( TO NITROGEN 14) HAS A HALF-LIFE OF ~6,000 YRS (5,730 DATES RECENT FOSSILS) SEDIMENTARY LAYERS ARE OFTEN DATED BY INTRUSIONS, EXTRUSIONS HALF-LIFE NOT USUALLY USED TO DATE SEDIMENTARY ROCK LAYERS SEDIMENTS MAY HAVE ALL DIFFERENT AGES AGE OF THE EARTH; ABOUT 4.6 BILLION YEARS OLDEST ROCKS ARE ABOUT 4.0 BILLION YEARS OLD EARTH'S AGE DERIVED FROM OLDEST MOON ROCKS slide 9

10 GEOLOGIC TIME: USED TO MEASURE THE HISTORY OF THE EARTH AS A PLANET
GEOLOGIC TIME IS BROKEN INTO 4 HUGE TIME UNITS CALLED ERAS ERAS ARE MARKED BY DRAMATICALLY DIFFERENT TYPES OF LIFE DRAMATIC CHANGES IN CLIMATE MAY DRIVEN THESE CHANGES IN LIFE THE PRECAMBRIAN IS THE LONGEST ERA (88% OF TIME, HAS NO PERIODS) PALEZOIC, MESOZOIC, AND CENOZOIC ERAS DIVIDED INTO PERIODS PERIODS HAVE LESS DRAMATIC CHANGES IN LIFE THAN ERAS PERIODS IN THE CENOZOIC ERA ARE BROKEN IN EPOCHS EACH NEWER ERA IS SHORTER THAN THE ONE BEFORE IT slide 10

11 LIFE THROUGHOUT EARTH'S HISTORY
THE PRECAMBRIAN ERA: THE LONGEST, BEGAN WITH EARTH'S FORMATION LAND, ATMOSPHERE DRAMATICALLY DIFFERENT THAN TODAY ONLY SIMPLE LIFE EXISTED, NO OXYGEN IN ATMOSPHERE BACTERIA-LIKE ORGANISMS AROSE ABOUT 3.5 BILLION YRS. AGO 1ST LIFE TO USE PHOTOSYNTHESIS AROSE ABOUT 2.5 BILLION YRS USED CARBON DIOXIDE, RELEASED OXYGEN OXYGEN ACCUMULATED IN ATMOSPHERE OXYGEN-BREATHING CREATURES DEVELOPED (WORMS, SPONGES) slide 11

12 THE PALEOZOIC ERA: MARKED BY ABUNDANT FOSSIL-FORMING COMPLEX LIFE
INCLUDES THE AGE OF INVERTEBRATES, AGE OF FISH, AGE OF AMPHIBIANS HAD A TOTAL OF 7 PERIODS, EACH MARKED BY DIFFERENT LIFE FORMS BEGAN ABOUT 545 MILLION YEARS AGO WITH THE CAMBRIAN EXPLOSION CAMBRIAN PERIOD: 1ST PALEOZOIC PERIOD, AGE OF INVERTEBRATES INVERTEBRATES: STILL MOST COMMON LIFE, HAVE NO BACK-BONES MANY TYPES OF LIFE HAD BONES & SHELLS ALLOWING FOSSILIZATION FIRST LAND PLANTS AND INSECTS APPEAR NEXT (SILURIAN PERIOD) PLANTS NEEDED AS BASE OF FOOD CHAIN ON LAND PHOTOSYNTHESIS CONVERTS SUNLIGHT TO FOOD, MAKE O2 slide 12

13 PALEOZOIC ERA (continued)
AGE OF FISH (FIRST VERTEBRATES) IN ORDOVICIAN PERIOD FIRST LIFE FORMS TO HAVE BONY VERTEBRA, SPINAL NERVE COLD BLOODED, USE GILLS, SCALES , LAY MANY EGGS FIRST AMPHIBIANS APPEAR IN DEVONIAN PERIOD SMOOTH SKIN, LAY MANY EGGS, HAVE GILLS AND LUNGS GO THROUGH LIFE CHANGES CALLED METAMORPHOSIS HUGE FERNS AND CONIFER FORESTS APPEAR, SOURCE OF COAL & OIL ENERGY STORED 500 MILLION YRS AGO NOW FUEL (MISS. PER.) CO2 STORED THEN NOW BEING RELEASED INTO ATMOSPHER E slide 13

14 PALEOZOIC (continued)
FIRST REPTILES, INSECTS APPEAR IN PENNSYLVANIAN PERIOD INSECTS: HARD EXOSKELETON, SEGMENTED LEGS, 3 BODY PARTS REPTILES: DRY SCALY SKIN, EYELIDS, LEATHERY EGGS, SIDE LEGS PERMIAN PERIOD THE LAST IN PALEOZOIC ERA PANGEA SUPER-CONTINENT FORMS (ONE SINGLE CONTINENT) HUGE CRUSTAL PLATES SLIDE ON MANTLE CONTINENTS’ EDGES ALIGNMENT INDICATE MOVEMNET FOSSILS FROM WEST AFRICA MATCH OF EAST AMERICAS’ MASS EXTINCTION (MASS SPECIES DEATH) MAKES THE ERA’S END KILLS ABOUT 90-95% OF ALL LIFE ON EARTH, IN OCEANS REPTILES AND FISH AMONG SURVIVORS slide 14

15 MESOZOIC ERA: PALEOZOIC SURVIVORS FILL ENVIRONMENTAL NICHES
TRIASSIC PERIOD: (~ 245 MILLION YRS AGO) MARKS AGE OF REPTILES FIRST DINOSAURS APPEAR FIRST MAMMALS APPEAR: SMALL, SHREW-LIKE NIGHT DWELLERS JURASSIC: BEGINS THE AGE OF THE DINOSAURS PANGEA BREAKS APART FIRST BIRDS, FLYING REPTILES APPEAR CRETACEOUS: HUGE DINOSAURS RULE EARTH FIRST FLOWERING PLANTS ( MOST COMPLEX ) APPEAR ENDS WITH MASS EXTINCTION BELIEVED CAUSED BY COMET CLIMATE CHANGED, MANY SPECIES BECAME EXTINCT DINOSAURS EXTINCT, MAMMALS AMONG SURVIVORS slide 15

16 CENOZOIC ERA: CURRENT ERA, SHORTEST ONE
PERIODS IN CENOZOIC BROKEN DOWN IN SMALLER UNITS CALLED EPOCHS TERTIARY PERIOD: MARKS THE AGE OF MAMMALS (65 MILLION YRS) MAMMALS: VERTEBRATES, HAIR, FEED YOUNG MILK, MOST LIVE BIRTH MAMMALS ARE WARM-BLOODED- ABLE TO MAINTAIN INTERAL TEMP. QUATERNARY PERIOD: CURRENT ONE, SHORTEST PERIOD INCLUDES THE AGE OF MAN, 1ST ONES ABOUT 3.5 MILLION YEARS AGO 1ST PRIMITIVE MAN- HOMO (genus) SAPIENS (species) ~ 100,000 YRS AGO MODERN MAN DATES BACK ABOUT 40,000 YEARS slide 16

17 QUARTENARY HAS ICE AGES, HUGE GLACIERS, LOWER OCEAN LEVELS
ICE AGES: COLDER PLANETARY TEMPS TRAPPED WATER IN GLACIERS ICE AGES OCCUR IN CYCLES, FOLLOWED BY GLOBAL HEATING GLACIERS: HUGE SECTIONS OF ICE COVERING LAND GLACIERS COVER MUCH OF NORTHERN CONTINENTS RETREATING GLACIERS CHANGED LAND IN Pa., N.Y., GREAT PLAINS slide 17

18 mammoth_hmed_11a.hmedium.jpg photos cited...

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