1. Provide Evidence of Change in organisms over time!
Fossils
Provide Evidence of Change in organisms over time!

2. What is a fossil? Preserved evidence of an organisms found
This happens once they die, decompose, and
become buried with sediment
Sediments build up in layers and are subject to intense pressure.
Therefore where will you find the oldest fossils?
Deeper in the layers of sediments

3. Fossil Types
Trace Fossil- Indirect evidence Ex. Footprint, feces, burrows
Molds and Casts- Impression or organisms
Amber- preserved in tree sap
Original Material- Mummification or freezing preserves bones, teeth, skulls, etc.
What is a person called who studies fossils?
Paleontologist

4. How do we know how old a fossil is?
Relative Dating- Determine dates of rocks by comparing them with those in other layers.
Law of Superposition- young layers deposited on top of old layers
Radiometric Dating- Decay of radiometric isotopes
Half Life- time it takes for half
of the original isotope to decay
(Uranium 238 or Carbon 14
dating less than 60,000 yrs old)

5. Geologic Time Scale
Record of Earth’s history……..more than 4 billion years….broken into subdivision
Largest to Smallest
Eon, Era, Period, Epochs

6. The Origin of Life Spontaneous Generation- 1668 Francesco Redi
Tested idea that flies arose spontaneously from rotting meat.
Observed maggots (fly larvae) appeared only in flasks that were open to flies.
Closed flasks had no flies or maggots
Not widely accepted
Gave rise to biogenesis…only living organism can produce other living organisms (Louis Pasteur)

7. Origin of Life: Modern Ideas
Topic of ongoing research….3 ideas all developed due to a series of chemical events early in Earth’s History.
1. Stanley Miller simulated Earth’s early atmosphere and discovered organic compounds such as amino acids, sugars, and nucleotides.

8. Simulation of Earth’s Early Atmosphere

9. Meteorites
Panspermia is a Greek word that translates literally as "seeds everywhere". The panspermia hypothesis states that the "seeds" of life exist all over the Universe and can be propagated through space from one location to another. Some believe that life on Earth may
have originated through
these "seeds".

10. Hydrothermal Vents
Hydrothermal Vents-deep sea where sulfur forms the base of a unique food chain

11. What were the first cells like?
The first cells are too old to be found as fossils so scientists predict the first cells were:
Prokaryotic
Survive in extreme environments
Anaerobic (Oxygen present until 1.8 billion years ago)
First Cells were photosynthesizing
Found fossils of Cyanobacteria that were 3.5 bil years old
Cyanobacteria eventually produced enough oxygen to support the formation of the ozone layer….leading to appearance of Eukaryotic Cells!

12. How does the Theory of Endosymbiosis explain the origin of Eukaryotic Cells
Prokaryotes might have lived inside Eukaryotes
Ingested or internal parasites
Relationship became mutually beneficial
Prok. symbionts became organelles in Eurk (Chloroplast and Mitochondria)

13. Evidence to support Endosymbiosis
Mitochondria and Chloroplast have their own circular DNA just like prokaryotes
Ribosomes that resemble those of prokaryotes
Mitochondria and Chloroplast reproduce through binary fission just like prokaryotes
This theory is widely accepted

14. Fossils
sediments
Relative dating
Radiometirc dating
organisms
Rock layers
Radioactive isotopes
minerals
age
fossils

15. Check the correct column for each statement
Precambrian
Paleozoice Era
Mesozoic Era
Cenozoic
Autotrophic prokaryotes enrich the atmosphere with oxygen X
Primates evolve and diversify
It is divided into three periods: Triassic, Jurassic, and Cretaceous
Many types of insects, land plants, and the first land vertebrates appear
Mammals appear
Dinosaurs roam the Earth, and the ancestors of present day birds evolve
Reptiles appear
Simple organisms, such as stromalites, live in marine ecosystems