1. THE ORIGINS OF LIFE ON EARTH
- evolution of species
- The nature of fossils
- How fossils provide evidence

3.
Human civilization, in its most widely used definition, dates entirely within the Holocene. It’s this time period from when humans have had a significant impact on the Earth's climate and ecosystems to the present.
Scroll down the page to see images of the geologic timeline
Click on a few of the geological time periods (incl. The holocene)
- Scrolling down the individual pages will tell you what species of animal lived during the time period and any other info
Scroll further and mention the 5 big extinction events
Cretaceous-Tertiary mass extinction - also known as the K/T extinction - is famed for the death of the dinosaurs. However, many other organisms perished at the end of the Cretaceous

4. The evolution of life http://www.wellcometreeoflife.org/
From David attenborough’s ‘tree of life series’
- There is an accompanying handout students can fill in if

5. EXTINCTION
The permanent loss of all the members of a species from the face of the earth

6. Environmental changes
The climate and environment on Earth is always changing
These are the main causes of extinction, animals are not able to adapt quickly enough to the change in their environment

7. Evolution of the earth: ice ages
Both videos discuss the snowball earth theory – the last ice age and its retreat

8. Again, the major eras, showing approx
Again, the major eras, showing approx. where the 5 big extinctions occurred (including the one for the dinosaurs further discussed on the following slides)
Cambrian is famed for its explosion of abundant and diverse life forms.

9. Hypothesis: Extinction of the dinosaurs
65 million years ago, a large meteor hit the earth
The impact caused a large amount of debris to go into the atmosphere.
This blocked the light and heat of the sun, causing the earth to cool: an ICE AGE
There have been many different ideas put forward to explain why the dinosuars died out. The two most likely are that their habitat slowly changed, and that a meteor impact triggered their extinction.
Gradualist theory
The gradualist hypothesis points to declines in the numbers and diversity of different groups of land and marine animals. - extinction due to climate change. The climate at the end of the Cretaceous was cooling - and a fall in sea level reduced dinosaur and shallow water marine animal habitats. Impact theory
- good geophysical evidence for the occurrence of an asteroid impact at the end of the Cretaceous. A band of clay rich in the mineral iridium was deposited at the end of the Cretaceous and has been found at many places in the world. This mineral is rare on Earth but more common in meteorites. It has been suggested that the impact would have triggered a nuclear winter scenario that would have caused the death of the dinosaurs as well as the pterosaurs, several families of birds and mammals and also marine animals such as the plesiosaurs and ammonites.

10. The Chicxulub crater in Mexico

11. Other causes of extinction
predator: new predator comes to an area and wipes out a lesser species
Disease: microorganisms can infect a species, killing it EX: Tazmanian Devil & cancer
Competition: a mutation gives one species and advantage, causing the other to be unable to keep up

12. FOSSIL FORMATION There is no record of the origins of life on earth
But, most scientists believe is was somewhere between 3 billion and 4.5 billion years ago!!

13. What is a fossil?
The following slides show examples of fossils that scientists have found.
Look carefully at each, and write down what you think they have in common.

14. Fossil One – Ammonite

15. Fossil Two - Turtle

16. Fossil Three – Sharks Teeth

17. Fossil Four – T. Rex

18. Fossil Five – Leaf

19. FOSSIL FORMATION
We share the Earth with millions of different species of living organisms
This is a tiny amount compared to the 4 billion species believed to have lived on Earth during its history

20. FOSSIL FORMATION
Fossils are the remains of plants and animals from thousands or millions of years ago
They are usually found in rocks

21. Fossils can be formed in different ways:
CASTS OF ANIMALS OR PLANTS
Formed when the hard parts of animals are replaced by minerals
Human casts from Pompeii

22. 2. IMPRESSIONS
- These fossils are not actually animals or plants but traces they have left behind
Ardley Quarry in Oxfordshire
- Dinosaur tracks!?

23. 3. ICE FOSSILS
Some animals/plants do not decay after death but are preserved in ice

24.
Fossil evidence of the earliest eukaryotes –in Australia
** mention what ‘snowball earth’ means as it’s mentioned in the video
- Snowball Earth describes a theory that for millions of years the Earth was entirely smothered in ice, stretching from the poles to the tropics.
it's now thought that there may have been more than one of these global glaciations. They varied in duration and extent but during a full-on snowball event, life could only cling on in ice-free refuges, or where sunlight managed to penetrate through the ice to allow photosynthesis.
2. Evolution of woolly mammoths – link to adaptions!