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FOSSILS & EVOLUTION. How do we know that there was life millions of years ago?? BY: BRIANNA SHIELDS. DO NOW. Please place your take home test on your desk. GOAL. To define fossil and to determine which types of fossils are older based on layering

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fossils evolution


How do we know that there was life millions of years ago??


do now
  • Please place your take home test on your desk
  • To define fossil and to determine which types of fossils are older based on layering
  • To define evolution and the 4 ideas associated with the theory
finding the age of fossils
Relative Dating of Fossils

Younger rocks (top layer) are found on top of older rocks (bottom layer)


Ex: Diagram A

Finding the Age of Fossils
finding the age of fossils5
Index Fossils

Fossils that lived during a short period of time

Can help in aging rock

Ex: Diagram E

Which are index fossils?

Which fossils are not as helpful for aging?

Finding the Age of Fossils
finding the age of fossils6
Fossil Age Rule

A fossil is the same age as the rock that it’s found in

Finding the Age of Fossils
life on earth according to fossils
What have fossils told us?

Life has existed on Earth for nearly 3 billion years

Life on Earth: According to Fossils
life on earth according to fossils9
What have fossils told us?

Simple life began in water, evolved, became terrestrial

Life on Earth: According to Fossils
life on earth according to fossils10
What have fossils told us?

Some organisms have become extinct

Trilobite, Woolly Mammoth, Dinosaurs

Life on Earth: According to Fossils
life on earth according to fossils11
What have fossils told us?

Some life forms have hardly changed

Ex: Cockroaches, snails, snakes

Life on Earth: According to Fossils

A group of similar organisms that can interbreed to make fertile offspring

Ex: All lions mate with one another

Lions + Tigers = infertile Ligers or Tiglons


A change in a species over time

Use the camel evolution diagram

Compare modern camels to their ancestors


How has man changed over time?

Lamarck’s Theory

Theory of use & disuse

An organism gets a new organ if it needs it

Use it more & it will grow bigger

New organ is passed to offspring

What do you think about the validity of Lamarck’s Theory? Give an example

Darwin’s Theory

Theory of natural selection

Better explanation of evolution

The survival & reproduction of the organisms best adapted to their surroundings

parts of the theory of natural selection
Theory of Natural Selection

Part One: Survival of the Fittest

Organisms overproduce offspring

Organisms that are better competitors or more fit, will survive

Parts of the Theory of Natural Selection
ex survival of the fittest
Ex: Survival of the Fittest
  • Dandelions produce many seeds
  • This ensures some will live- others will not be able to find enough food & sunlight
ex survival of the fittest24
Ex: Survival of the Fittest
  • Tadpoles- many hatch at once
  • Fierce competition- stronger, faster ones will find food faster & outrun enemies
parts of the theory of natural selection25
Theory of Natural Selection

Part Two: Variation & Adaptation

Offspring that survive have structures or ADAPTATIONS that make it more fit for its environment

Certain differences or variations help some to outcompete others

Even within a species

Ex: Finch Beaks

Parts of the Theory of Natural Selection
variation adaptation example
Variation & Adaptation Example
  • How would a variation in polar bear coats help certain polar bears to have greater fitness?
    • There are variations in polar bear coats
    • Some polar bears have thicker coats of fur than others= better protection to cold
    • They are more likely to survive- this adaptation to their surroundings makes them a better competitor
variation adaptation example29
Variation & Adaptation Example
  • What happens to the fitness of a thick coated polar bear if the environment become warmer?
  • Which type of polar bear has the better variation in coat?
  • “The fittest that survive may change with their surroundings”
parts of the theory of natural selection30
Part Three: Reproduction

Individuals that are more fit:

Survive longer

Reproduce more

Pass on the beneficial traits or differences

Evolution Library: Topic Page

Parts of the Theory of Natural Selection
what causes evolution
Causes of Evolution

Mutations or natural accidental mistakes in the animal’s DNA

What causes evolution?
what causes evolution32
Causes of Evolution

Negative Mutation: Organism dies because it can’t compete (extinction)

Positive Mutation: Organism becomes a better competitor- increases survival & reproductive chances

What causes evolution?

Occurs when many small adaptations occur over time (or negative mutations)

Those with new adaptations outcompete old “versions” of the species

  • A hummingbird’s beak, giraffe’s neck & vampire bat’s teeth all help them to do what better?
  • What are adaptations- how do they affect the organism?
evidence supporting evolution
Evolutionary Evidence

1. Fossil Record- documents the change in organisms over billions of years

Evidence Supporting Evolution
evidence supporting evolution37
Evolutionary Evidence

2. Anatomical Evidence- similar body structures

Homologous Structures= similar body parts that evolve suggest common ancestry

Evidence Supporting Evolution
homologous structures
Homologous structures
  • What similarities do you see among the structures in diagram B?
  • What do these homologous structures indicate?
evidence supporting evolution40
Evolutionary Evidence

3. Embryological Evidence- similarities in the embryos of very different organisms

Evidence Supporting Evolution
evidence supporting evolution42
Evolutionary Evidence

4. Chemical and Molecular Evidence

The more similar the DNA code, the more closely related two organisms are

Evidence Supporting Evolution
peppered moth scenario
Peppered Moth Scenario
  • Look at drawing on side board
  • Nowhere to Hide
peppered moth scenario45
Peppered Moth Scenario
  • Which moth ended up being more “fit” or a better survivor or competitor? Why?
  • Answer the questions on your peppered moth sheet
  • “Becoming Human” interactive documentary
  • BBC- Burying Bodies
  • BBC- Making Fossils
Explain why many animals/plants don’t become fossils?

Many remains are crushed, ruined, eroded, rotted, eaten or burned before they become fossils

What types of objects make the best fossils?

Hard parts- teeth, shells, bones, wood

Describe where most fossils are formed and how they actually form.

Many fossils form in sedimentary rock that used to be covered by oceans. When organism dies, gets buried by sediment in ocean, soft parts rot, hard parts preserved by sediment

Tell about the difference between a mold and a cast

Mold is hollow space left in sediment when animal rots, cast is when mold gets filled back in with other sediment

Explain how changed hart parts fossils are formed

When actual body parts fill with minerals changing them to a harder substance

Compare techniques used for dating fossils

Law of superposition (relative dating), index fossils, absolute dating

assessment 1
Assessment 1
  • Read the evolution article
  • What is the author’s point of view? Do you agree or disagree with him?
  • Support your viewpoint with evidence from your notes
assessment 2
Assessment 2
  • A change in the future that may affect the evolution of living things is global warming
  • How might global warming affect evolution? Why?
  • Please write the following assignment into your agenda:
    • Fossil and Evolution Review Questions