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
slide 1
 PALEONTOLOGISTS: SCIENTISTS WHO STUDY FOSSILS
EIGHT TYPES OF FOSSILS
1. PETRIFIED: LIVING TISSUE TURNED INTO STONE
 THE REMAINS ABSORBS WATER WITH DISSOLVED MINERALS
 TISSUE SLOWLY DECAYS, LEAVES MINERAL-HARDENED FOSSIL
2.
MOLD: HOLLOW IN SEDIMENTARY ROCK FORMED BY AN ORGANISM
3.
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
slide 2
 CREATES IMPRESSION OF ORIGINAL LIVING
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
slide 3
8. FREEZING: PRESERVES FLESH AND BONE IN PLACES SUCH AS ALASKA
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
slide 4
 THEORY: AN UNPROVEN EXPLANATION BASED ON EVIDENCE
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
slide 5
 ANTARTICA ONCE A HOT, SWAMPY, RAIN FOREST
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
slide 6
 GRAND CANYON: OLDEST FOSSILS ARE AT BOTTOM OF CANYON
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
slide 7
 MAY BE CAUSED BY EROSION OF SOFTER TOP LAYERS
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
slide 8
 AN ELEMENT'S HALF-LIFE IS USED TO DETERMINE ITS ABSOLUTE AGE
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
slide 9
EARTH'S AGE DERIVED FROM OLDEST MOON ROCKS
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
slide 10
 EACH NEWER ERA IS SHORTER THAN THE ONE BEFORE IT
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
slide 11
 OXYGEN-BREATHING CREATURES DEVELOPED (WORMS, SPONGES)
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
slide 12
 PHOTOSYNTHESIS CONVERTS SUNLIGHT TO FOOD, MAKE O2
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.)
slide 13
 CO2 STORED THEN NOW BEING RELEASED INTO ATMOSPHER E
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
slide 14
• REPTILES AND FISH AMONG SURVIVORS
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
slide 15
 DINOSAURS EXTINCT, MAMMALS AMONG SURVIVORS
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
slide 16
 MODERN MAN DATES BACK ABOUT 40,000 YEARS
 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
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