EVOLUTION The History of Life Lecture 11 Southern Boone County HS College Biology Mr. Palmer

Early History of the Earth About 4.6 BYA Earth forms Very Hot Many meteorites colliding with earth Volcanoes Radioactive material Little Oxygen Lots of Water, Carbon Dioxide, and Nitrogen

Early History of the Earth 3.9 BYA-earth cools and water condenses 3.5 BYA first life forms in oceans

Early History of the Earth Fossils are clues to the past Fossil-any evidence of an organism that lived long ago Today’s millions of species are a small fraction of all the species that have ever lived Paleontologist-person who studies ancient life

Early History of the Earth Fossils can tell a lot about organisms Teeth-what it ate Bones-overall size Leaves-climate Coprolites-what it ate

Early History of the Earth Most fossils are found in sedimentary rocks when they are buried by sand, mud, or clay Some fossils get caught in tree sap-Insects in amber (Jurassic Park) Some fossils get buried by ash from volcanoes Usually not in metamorphic or igneous rocks

Early History of the Earth Relative Dating-used to tell relative ages-A is older than B; B is younger than D, etc. Oldest rock are usually on the bottom; youngest rocks are usually on top A process called folding can change the order

Early History of the Earth Radiometric Dating-using radioactive isotopes to determine the exact age of a fossil Half Life is how long it takes for ½ of a radioactive element to decay Carbon-14 can date materials to about 50,000 YO Potassium-40 can date materials to billions of years old

Early History of the Earth Geologic Time Scale-the chronology of the earth’s history There are 4 eras Precambrian Paleozoic Mesozoic Cenozoic

Early History of the Earth Eras are divided into periods Divisions are characterized by the organisms that lived in them There were apparently times when many organisms died off-Mass Extinctions

Early History of the Earth Life in the Precambrian Oldest fossils are 3.5 BYO found in Australia Simple bacteria Stromatolites Simple prokaryotic cells 1.8 BYA eukaryotic cells appear Sponges and jellyfish 544 MYA

Early History of the Earth Life in the Paleozoic Lasted until 245 MYA Many simple plants and animals Worms, starfish, arthropods Simple fish, ferns, seed plants First amphibians come onto land At the end of the Paleozoic era there was a mass extinction that killed about 90% of marine species and 70% of land species

Early History of the Earth Life in the Mesozoic Triassic Period Began about 245 MYA Fossil mammals-small and mouse-like Dinosaurs, reptiles

Early History of the Earth Life in the Mesozoic Jurassic period Began 208 MYA Age of dinosaurs-T rex, Velociraptor, Modern birds appear Giant Mass Extinction

Early History of the Earth Life in the Mesozoic Cretaceous period Began 144 MYA Many new mammals Flowering plants Giant Mass Extinction 66 MYA Killed dinosaurs and 66% of all species Meteorite that hit gulf of Mexico off of East coast of Mexico filled atmosphere with a thick cloud cooling earth and causing the mass extinction

Early History of the Earth Life in the Mesozoic Continental Drift-plate tectonics

Early History of the Earth Life in the Cenozoic Began 66 MYA Many Mammals First primates appeared 30 MYA Modern humans appeared 200,000 YA

Early History of the Earth Wrap up 1.How old is the earth? 2.Name three gases that were on early earth? 3.List three sources of heat on early earth. 4.How long ago did water condense on earth? 5.How long ago did the first life appear on earth? 6.What is a fossil? 7.What do you call a person who studies fossils? 8.Give four examples of how a fossil or part of a fossil can tell you about the organism.

Early History of the Earth Wrap up 9. Where did the DNA for the Jurassic Park dinosaurs come from? 10. What is radiometric dating? 11. What is the chronology of the earths history called? 12. List the four eras. 13. How are eras broken down? 14. What is a mass extinction?

Early History of the Earth Wrap up 15. What is a mass extinction? 16. What kind of organisms are found in the Precambrian? Samples? 17. What kind of animals are found the the Paleozoic? 18. When did the Paleozoic begin and end? 19. What kind of animals were found in the Cenozoic Period? 20. When did humans first appear? 21. When were two mass extinctions?