Journal #54 What is evolution? How do you think evolution has affected the Earth?

Today, we will identify characteristics of the Precambrian and Paleozoic Eras

Evolution Fossils indicate the kinds of organisms that lived when rock formed. By examining these rock layers and fossils, scientists have discovered evidence that species of living things have changed over time. Evolution is the gradual development of new organisms from pre-existing organisms.

Evolution Evolution occurs by means of natural selection The theory of evolution by natural selection was proposed by Charles Darwin. Evolution is the heritable change in the characteristics within a population from one generation to the next Example is peppered moths

Geologic Change Major geologic and climatic changes can affect the ability of some organisms to survive. By using geologic evidence, scientists try to determine how environmental changes affected organisms past. The fossil record shows that some organisms survived environmental changes while others disappeared. Video http://app.discoveryeducation.com/search?Ntt=precambri an+time

Precambrian Time The Precambrian Era makes up about 88% of the Earth’s history. We know very little about what happened during this time. Most of the rocks have been deformed by tectonic activity Large areas of Precambrian rocks are called shields. They are the result of volcanic activity, mountain building, sedimentation, and metamorphism.

Precambrian Life Most of the fossils have been destroyed Lacked bones Most common is stromatolites- reeflike deposits formed by blue-green algae Video on Stromatolites http://app.discoveryeducation.com/search?Ntt=strom atolites

Paleozoic Era Began 542 mya and ended 251 mya At the beginning of this era, the earth’s landmass was scattered around the world. By the end, these landmasses collided together to form the super continent called Pangaea.

Paleozoic Era Unlike the Precambrian, the Paleozoic had a large number of plant and animal species. Rich in fossil records Divided into 7 periods Cambrian Period Ordovician Period Silurian Period Devonian Period Carboniferous Period Mississippian period Pennsylvnian period Permian Period

Cambrian Period

Your Assignment: Complete the graphic organizer Describe the environment of each period and identify at least one life form that existed during that time.

What is Our Learning Goal? What percentage of Earth’s history is in the Precambrian Era? What was the dominant life form during this Era? Describe the Paleozoic Era.