Changes in the Fossil Record A look at the theory of evolution

 The geologic history of the earth is recorded in the rock layers by the fossils that lie within them. Using sites such as the Grand Canyon, we are able to date our Earth.  These fossils have changed throughout Earth’s history.

Theory of Evolution  By examining rock layers and fossils, scientists and paleontologists have found evidence that supports the theory of evolution.  Basically, the theory states that organisms adapted as our Earth changed throughout history.

Wait…  Hasn’t earth been the same since it came into existence?

How did the atmosphere shape evolution?  Early Earth’s atmosphere (pre- Cambrian)= composed mainly of hydrogen and helium  They are very light gases so gravity could not keep them from escaping into space  What’s in our atmosphere now? Why can’t they escape into space?  Nitrogen and oxygen, are high in mass and can’t escape.

Volcanoes and the Ocean  Volcanoes gave off water vapor.  Water vapor condensed into clouds  Clouds made rain and over time filled our oceans.

Oxygen in the Atmosphere  This early Precambrian atmosphere did not have oxygen!  How could life have existed???  Volcanic eruptions during Precambrian time vented steam, ammonia (NH3) and carbon dioxide into the atmosphere.

Early Building Blocks of Life  Proteins and amino acids were created from water through lightning strikes.  As more and more were created, they started combining and became the building blocks of life  Primitive cells began to exist.

Cyanobacteria  Fossils of tiny bacteria called, cyanobacteria have been found in rocks 3.5 billion years old.  Knowledge check: How do we know the rocks are 3.5 billion years old?  These bacteria performed photosynthesis and added more oxygen to the atmosphere

OXYGEN  This paved the way for life as we know it to form  Not only do animals need oxygen to live, but we also need Ozone, which is made of oxygen, to protect us from harmful radiation from the Sun.

Theory of Evolution  Theory of evolution- organisms react to changes in the environment over time  New kinds of organisms come from old ones

How Plants Evolved  Plants evolved by single celled organisms  algae  nonvascular  vascular  cone bearing  plants with flowers

How Animals Evolved  Animals evolved by Invertebrates (animals without a backbone)  fish  amphibians  reptiles  mammals The tentative “missing link” found in 2006!

Charles Darwin  Darwin’s Theory- “Survival of the fittest” 1) Organisms must adapt to their surroundings 2) Changes in the environment affect organisms 3) Only those who can adapt to changes will survive 4) Organisms that can’t adapt die and become extinct

Extinction  Most major extinctions happen because of environmental changes  Ex) Marine life at the end of the Cretaceous or Dinosaurs at the end of the Mesozoic Era.

Extinctions A large circular crater near the Yucatan Peninsula in Mexico was found by geologists to be about 65 million years old. This crater is thought to be evidence of the extinction of the dinosaurs.

Religious issues with Theory  Nature goes to chaos  Not sure of times involved  No mention of dinosaurs in Bible  Do you have to have “Evolution vs. God”?