THE ORIGINS OF LIFE ON EARTH evolution of

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

• http: //www. bbc. co. uk/nature/history_of_the _earth • 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.

The evolution of life http: //www. wellcometreeoflife. org/

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

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

Evolution of the earth: ice ages • http: //www. bbc. co. uk/nature/history_of_the _earth/Cryogenian#p 00 cgy 7 m • http: //www. bbc. co. uk/nature/history_of_the _earth/Cryogenian#p 00 cgym 0

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

The Chicxulub crater in Mexico

Other causes of extinction 1. predator: new predator comes to an area and wipes out a lesser species 2. Disease: microorganisms can infect a species, killing it EX: Tazmanian Devil & cancer 3. Competition: a mutation gives one species and advantage, causing the other to be unable to keep up

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!!

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.

Fossil One – Ammonite

Fossil Two - Turtle

Fossil Three – Sharks Teeth

Fossil Four – T. Rex

Fossil Five – Leaf

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

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

Fossils can be formed in different ways: 1. CASTS OF ANIMALS OR PLANTS - Formed when the hard parts of animals are replaced by minerals Human casts from Pompeii

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

3. ICE FOSSILS - Some animals/plants do not decay after death but are preserved in ice http: //www. youtube. com/watch? v=jl 73 TOqid 0 w&featur e=related

• http: //www. youtube. com/watch? v=Zo 49 Pyhii -k&feature=fvwrel • http: //www. youtube. com/watch? v=jlw. MYno. C Gs. M&feature=relmfu