A. Geologic time—Earth’s history is divided into time units that make up a geologic time scale.

1. Units on the scale are based on appearance/disappearance of organisms such as trilobites, index fossils that lived in specific time periodsB. Four major divisions of Geologic Time.

1. Eons—longest subdivision; based on abundance of fossils 2. Eras—marked by significant worldwide changes in the types

of fossils present in rock3. Periods—based on types of life existing worldwide at a

particular time4. Epochs—characterized by differences in life-forms, but

differences can be regional rather than global

Pre-Cambrian Time

- Lasted from 4.5 billion years ag0 until 544 million years ago

- Few Life forms existed at this time- Single cell organisms, such as

CYANOBACTERIA dominated- Invertebrates appeared during this

time (similar to jellyfish and corals), left trace fossils

- Major geologic events: Earth was cooling

- “Cambrian” explosion- rapid spread of inverts marked the end of the Pre- Cambrian

Cyanobacteria

• Grow in mats called stromatolites

• These photosynthetic bacteria created much of the oxygen in the early atmosphere

Paleozoic Era

- 544 million to 248 million years ago- Dominated by invertebrates that

lived in oceans (lots of shelled animals)

- First land plants /animals and vertebrates (fish, reptiles, and amphibians) appear

- Several mountain building events, including the building of the Appalachian Mountains occurred in this era; creation of PANGAEA

- Ended with a mass extinction (cause still debated)

What characteristics of reptiles, allowed them to be the first animals to move away from the water?

Protective scaly skin, eggs that could be laid away from water, claws for digging and climbing

Mesozoic Era

- 248- 65 Million years ago- “Age of the Dinosaurs”- dominated

by reptiles- Birds, Mammals, and Flowering

plants appear in this era- Major Geologic Events: break- up of

Pangaea and eventual formation of current continents

- Ended with a mass extinction, possibly caused by a comet or meteor striking the Earth

Who survived?

What organisms survived the mass extinction of 65 million years ago?

Cenozoic Era

- 65 million years ago until today- Dominated by mammals- Humans first appear during this time- The Alps, Andes and Himalayan

mountains formed

C. Organic evolution—Organisms have changed over time, most likely because of environmental changes.

D. Species—organisms that normally reproduce only with other members of their group

E. Darwin’s theory of natural selection—organisms more adapted to an environment are more likely to reproduce

1. Natural selection within a species occurs only if characteristics present in some numbers increase their survival.

2. Artificial selection—breeding individuals with desired characteristics; humans use this type of selection when breeding domestic animals.

3. New species can evolve from natural selection.

Species a group of organisms that normally reproduces only with other members of their group.

2 members of the same

species – fertile

offspring

2 different species – non fertile offspring

Ex: 2 dogs

Ex: a lion and a tiger

Even though 2 organisms look

nearly alike, if the populations they

each come from do not interbreed naturally and

produce offspring that can reproduce, the 2 individuals do

not belong in the same species!

Natural Selection Activity

1. Create a table on your paper that looks like the one above.

2. Lay the dark green piece of paper on your table.

3. Pour the tiny pieces of paper from the envelope onto the green paper.

4. You will have 15 seconds to pick up as many of those pieces of paper as you can and place off to the side of the green paper.

5. Count how many of each color is left on the paper and record it in the table.

6. Repeat same process with your partner.

Dark Green Light Green Yellow Red Blue

Name Person 1

NamePerson 2

1.What color did you have the most of

left?2.Why do you think

that you had the most of that

color???

Natural Selection

- Charles Darwin – published a book – theory of evolution by natural selection- is a process by which organisms with characteristics that are suited to a certain environment have a better chance of surviving and reproducing than organisms that do not have these characteristics.- organisms compete with each other for resources necessary for life (ex: food, living space)

- differences could hurt or help an organism stay alive(these are called adaptations)

“Survival of the fittest.”

better adapted – live longer, better chance of producing offspringless adapted – shorter life, less chance of producing offspringSo, the better adapted genes are passed on more often.According to Darwin, this cause species to change over time.

Short neck giraffe

(rare)

Long neck giraffe

(common)

Amount of short Amount of short neck giraffes neck giraffes

has decreased has decreased over time.over time.

Artificial Selection- used by humans to breed animals- carefully choosing individuals with desired characteristics- Can you name three breeds of dog?

Bellwork 10/7/10

Answer in complete sentences- to be turned in:

1. What characteristics of reptiles, allowed them to be the first animals to move away from the water?

2. How would life be different today if cyanobacteria had not produced oxygen for Earth's atmosphere?

3. Explain why mammals could not be dominant until the Cenozoic era?

F. Plate Tectonics- Continental collisions formed the giant landmass Pangaea near the end of the Paleozoic Era. These collisions may have dropped sea levels

- May have caused extinction of Trilobites

Movement of the Continents

Lightly color landmasses these colors on both maps:

-North America- Purple- South America- Red-Europe/ Asia- Green- India- Yellow-Africa- Orange- Australia- Brown