1. Evolution- The Fossil Record 15.1 pp. 279-281
Evolution = change in the DNA over time
Individuals don’t evolve, only populations can evolve, over time
Evolution is the best scientific explanation for the diversity of life we see around us
Evolution has never been shown to be wrong
Why does evolution have to happen over time?

2. Evolution- The Fossil Record 15.1 pp. 279-281
Fossil = some physical trace of a long-dead organism
Develop under certain conditions: tar pits, sedimentary rocks
Not the actual body anymore, no DNA available
Usually left by hard body parts (bones, teeth, claws, feathers….)
Not bones, but images of bones
Hard body parts get replaced by minerals
Amber = special case of fossilized tree sap
Sometimes contains well preserved insect exoskeletons
Does not preserve DNA
Where do we find fossils?

3. Evolution- The Fossil Record 15.1 pp. 279-281
Law of superposition = rock layers on top are younger than rock layers below them
Dirty laundry pile rule: stuff on top is newer
Soil and rock develop deposited over time by wind and water
Relative age = age of a fossil compared to age of other fossils
Absolute age = how old it is in years (use half-lifes)
How long does it take rock to form?

5. Evolution- The Fossil Record 15.1 pp. 279-281
Extinct = a certain kind of organism (species) is no longer living on earth
Mass extinctions = lots of different kinds of organisms go extinct in a short period of time (few thousand years)
Once extinct the organisms can’t come back (no DNA being passed on)
Extant = organism is currently living on earth (humans are extant)
What could cause a mass extinction?