1. Evolution: A Remodeling process
Section 15.2

2. Refinement of Existing Adaptations
Any living organism may have many adaptations.
A complex structure may have evolved from simpler structures.
Ex: Camera –like eye of mammals has evolved from simpler eye types

3. Adaptation of Existing Structures to New Functions
Flippers of Penguins modified wings

4. Development Feet in various salamanders
Salamanders  vertebrates closely related to frogs, live in land or water, but some live in trees
Tree dwelling ones have feet adapted to climbing
Ground Dwelling
Tree Dwelling w/
more webbing

5. Fossil records
Section 15.3

6. Formation of Fossils
Fossil Records and the Geologic Time Scale
Dating Fossils
Continental Drift
Mass Extinction

7. Fossil Records and the Geologic Time Scale
Most Recent Layers: Top
Oldest Layers: Bottom

8. Geologic Time Scale Distinct Ages in Earth’s History Precambrian
Paleozoic
Mesozoic
Cenozoic
See fig p337

9. Dating Fossils
Relative Dating
Absolute Dating
Radioactive Dating

10. Relative Dating Determines the Order in which events occurred
Not Actual Age

11. Absolute Dating
Determines how long ago an event occurred: Actual Age

12. Radioactive Dating
Based on measurement of certain radioactive isotopes.
Used to determine the absolute ages of rocks and fossils
Measured in Half-Life

13. Half-Life
Time required for a radioisotope to lose ½ of its radioactivity.
Ex: Carbon-14: ½ life ~ 5730 yrs. decays into Nitrogen-14

14. Carbon-14 is produced in the atmosphere fairly constant rate
14C is constant in all living things. When an organism dies, it no longer picks up 14C.
By comparing the activity of a sample with the activity of living tissue time an organism has been dead

16. Continental Drift
Land masses on different plates change positions as a result of movement

18. Mass Extinction
Long periods of relative stability broken by comparatively brief episodes of species loss
5 or 6 over the last million years