1. Name: Date: Tue 11/18/15 Topic – Ch3L3 – The Cambrian Explosion (Pages 106-111) Query: (SC.7.E.6.4) How did asteroid impacts affect Earth’s environment? Student Objective I can describe how asteroid impacts affect Earth’s environment. I Do/We Do – Guided notes and Class discussion You/Do – Student/Teacher choice menuStudent/Teacher choice menu

2. The Cambrian Explosion

3. Phanerozoic Eon Phanerozoic Eon: the period of time 542 million years ago to the present Means visible life This was a period when the fossil record started increasing in frequency and in variety

4. Phanerozoic Eon Cambrian Period: the beginning of the Phanerozoic Eon Fossils from this time were large enough to be seen without a microscope Trilobite: organisms that, based on the fossil record, started to develop hard shells ◦hard parts fossilized more easily than soft bodies Cambrian Explosion: refers to the fact that this period of time showed a great diversity of organisms

5. Environmental changes Changes in the environment is hypothesized to be responsible for the Cambrian Explosion Temperatures started to rise, along with sea levels ◦This produced new warm, shallow seas ◦These new seas gave new environments for organisms to evolve.

6. Environmental changes These new environments offered some challenges for life Adaptation: characteristics that species develop over time that help them survive a particular environment This wasn’t good for the species that didn’t adapt to this change Extinction: when all the members of a species die off. The fossil record here shows many places of change => many species came about as well as went extinct

7. Asteroids Asteroidal impact is one of the environmental changes that is believed to have brought about a mass extinction ◦If it is large enough, it can distort and change the environment ◦Large impacts could throw huge dust clouds up into the atmosphere, blocking out sunlight. ◦What do you think would be the first to go? If the change is sudden enough, there might not be enough time for a species to adapt

8. Final note Mass extinctions are generally followed by periods of rapid evolutionary changes. This is a continuous process

9. Vocabulary – 12 words – Chapter 3 Lesson 1 – p88Lesson 2 – p96Lesson 3 – p106 1.Principle of superposition 2.Fossil 3.Radioactive decay 4.Half-life 5.Geologic time scale 1.Hadean eon 2.Archean eon 3.Proto-continent 4.Proterozoic eon 1.Phanerozoic eon 2.Adaptation 3.Extinct