1. Rock ID Interactive http://www. learner

2. RELATIVE DATING-NOT DATING YOUR COUSIN!
GEOLOGIST noticed that certain types of rock could always be found in the same vertical order
If they knew the type of rock and how old it was then …
The age of the rock can be estimated by its position in the rock layers.
Older layer
Newer layers

3. RADIOACTIVE DATING-YOU HAVE A GLOW ABOUT YOU! Dating the age of Earth
The age of rocks can be determined by what element(s) it is made from
As you recall, many elements are radioactive (isotopes)
ATOMS DECAY OVER TIME SO…

4. URANIUM 238 HALF LIFE is 4.5 Billion years
When URANIUM decays it becomes LEAD
Scientist determine ROCK AGE by comparing Uranium to Lead RATIO
If the ratio of uranium:lead is higher then, is the rock younger or older?
younger

5. Radioactive Dating is More Exact Dating of Fossils
When the atoms decay they become new elements because the number of sub atomic particles has been reduced.
The decay rate of an element is called HALF LIFE.
HALF LIFE Is the time it takes for half the atoms of a molecule of an element to decay.
Half life animation

6. C14, CARBON DATING of ONCE LIVING ORGANISMS
The element Carbon exists as radioactive Carbon14 & non-radioactive Carbon12
Living cells take in BOTH forms.
When cells die they no longer take in C14.
The longer an organism is dead, the lower the ratio of C14 :C12
C14 CARBON’s half life is 5,730 YEARS
So after 5,730 years ½ is left,
11,460 2 half lives ¼ is left,
17,190 3 half lives 1/8 is left,
22,920 4 half lives 1/16 is left
Can date clothing, bones, some prehistoric items, etc

7. FOSSIL RECORD
Information of the GEOLOGICAL RECORD of EARTH. Can tell us about climate, life forms.
SEA CREATURES IN ARIZONA,
COASTLINE CHANGES
GIANT FERNS IN N. AMERICA
WARMER CLIMATE
WHAT DOES A PALEONTOLOGIST STUDY?
Fossils, bones

8. MOST FOSSILS ARE FOUND IN WHICH TYPE OF ROCK?
FORMATION OF FOSSILS
MOST FOSSILS ARE FOUND IN WHICH TYPE OF ROCK?
SEDIMENTARY ROCK -SEDIMENT FORMS WHEN SAND & SILT FROM WATER SETTLE TO THE BOTTOM OF A BODY OF WATER
Animals & plants that die in the water are compressed by pressure from sediments and water

9. FORMATION OF FOSSILS
BONES & TEETH can be preserved by SAND, MUD OR VOLCANIC ASH.
Footprints or soft tissue can be preserved by ash, but this is very rare. They have no hard parts so they are harder to make impressions and molds.
Sap from trees can trap insects, & plants and preserve them. The sap is preserved is called Amber.

11. FORMATION OF FOSSILS
PETRIFICATION can occur when the remains are covered with water
DISSOLVED MINERALS from the water replace the decaying tissues & hardens like stone.

12. Petrified wood

13. GAPS IN THE FOSSIL RECORD
Why are there gaps in the fossil record?
CONDITIONS TO FORM FOSSILS NOT PRESENT
SOME TISSUES ARE TOO SOFT TO FORM FOSSILS-JELLY FISH, WORMS
EROSION DESTROYS FOSSILS
FOSSILS CAN BE BURIED AND NOT FOUND

14. How to determine Ancestry COMPARISON OF LIVING ORGANISMS
EMBRYOLOGY
CHARACTERISTICS LOST IN ADULTHOOD are present in unrelated embryo species
ALL VERTEBRATE EMBRYOS HAVE GILL POUCHES-NECK FOLDS
IN FISH DEVELOP INTO GILLS
IN HUMANS-EAR BONES
This is evidence of inheritance from a fish-like ancestor.
The common ancestor of these organisms passed on a gene for development in the embryonic stage.
Mutations passed on changes to the adult form to create differences in anatomy and evolvement to new species.

16. COMPARATIVE ANATOMY
HOMOLOGOUS STRUCTURES -SIMILAR STRUCTURES DUE TO A COMMON ANCESTOR

17. COMPARATIVE ANATOMY
ANALOGOUS STRUCTURES -Similar looking but not from a recent, common ancestor.

18. COMPARATIVE ANATOMY
VESTIGIAL STRUCTURES -INHERITED from an ancestor, but no longer used
Whale pelvis

19. COMPARATIVE BIOCHEMISTRY big picture
COMPARISON OF GENETIC SEQUENCES among organisms.
HOW CLOSELY RELATED ORGANISMS ARE TO EACH OTHER comparing their genes
Organisms with a recent COMMON ANCESTOR
HAVE SIMILAR GENE SEQUENCES
This has caused re-thinking of the ancestry of some animals.

20. OLD SCHOOL THINKING
NEW SCHOOL

21. OLD SCHOOL
NEW SCHOOL

22. CLADOGRAM-shows ancestral relationships, timeline http://www. pbs