1. Wednesday, April 27 th Big Idea: What are fossils? Daily target: I can examine fossils and interpret evolution and time periods. Homework: Darwins Theory W/S (4/29) Vocabulary: Law of Superposition: says that older rock layers are on the bottom of a formation and younger rock layers are on the top. index fossil: is a fossil used to identify a certain geologic period. Entry Task: What kinds of fossils would you expect to find in limestone? Conclusion: What era does the largest fossils come from and which period do mammals first appear? Plan for Today: Relative Dating ppt OPEN NOTE EXAM TUESDAY 5/3/2016 MS-LS4-1 Analyze and interpret data for patterns in the fossil record that document the existence, diversity, extinction, and change in life forms through out history of life on earth under the assumption that natural laws operate toady as in the past.

2. Relative Dating Relative dating: looks at where the fossil is located to determine its age relative to other fossils. This only works if the area has been undisturbed.

3. Absolute Dating Uses radioactive elements near the fossils to determine the actual age of the fossils. By determining the age of the radioactive element, scientists can calculate the age of the fossil buried nearby. The absolute age of fossils is estimated by dating associated igneous rock and lava flows.

4. Fossil Record The dating of all fossils is included in the Geological Time Scale. This scale divides the time that the earth has existed into 4 eras. Eras are then divided into periods based on common events in that time period.

5. Pre- Cambrian Began with the formation of the Earth 4.6 billion years ago. Bacteria appeared 3.5 billion years ago, followed by algae and fungi.

6. Paleozoic Era Divided into 6 periods: Cambrian period - Sponges, snails, clams and worms evolve Ordovician period - First fishes evolved and other species become extinct Silurian period - Land plants, insects and spiders appear

7. Devonian period - Amphibians evolve and cone-bearing plants start to appear. Carbonferous period - Tropical forests appear and reptiles evolve. Permian period - Seed plants become common and insects and reptiles become widespread. Sea animals and some amphibians begin to disappear.

8. Mesozoic Era Divided into 3 periods: Triassic period - Turtles and crocodiles evolve and dinosaurs appear. Jurassic period - Large dinosaurs roam the world. First mammals and birds appear. Cretaceous period - Flowering plants appear, mammals become more common, dinosaurs become extinct.

9. Cenozoic Era Divided into 2 periods: Tertiary period - First primates appear and flowering plants become the most common. Quaternary period - Humans evolve and large mammals like woolly mammoths become extinct.