Investigating Evidence for Mass Extinctions

Name: _________________________________________________ Period: ___________ Date: ________________ Mass Extinction Laboratory Activity – Teacher Edition Answers: Investigating Evidence for Mass Extinctions Background Information: Animals and plants disappear all the time as extinction is a natural part of life. About 98% of all the organisms that have ever existed on our planet our now extinct. When a species goes extinct, its role in the ecosystem is usually filled by new species, or other existing ones. Earth’s “normal” extinction is rate is often thought to be somewhere between 0.1 and 1 species per 10,000 species per 100 years. But when species vanish much faster than they are replaced, this is known as mass extinction. It is usually defined as about 75% of the world’s species being lost in a “short” amount of geological time which is less than 2.8 million years. At least five mass extinctions have been recorded throughout Earth’s history. The vast majority of plant and animal species have been annihilated in a geologic instant five times. What triggered these dramatic events? What might they tell us about the fate of Earth? In this laboratory activity, you will explore an online simulation that will allow you to investigate the different evidence for mass extinctions. Name: _________________________________________________ Period: ___________ Date: ________________ Mass Extinction Laboratory Activity – Teacher Edition Learning Objectives: At the end of this laboratory activity, students are expected to: • Explore the Earth Viewer online simulation to be familiar with different geologic events • Identify evidence for mass extinctions based on the biodiversity before and after the extinction Laboratory Proper: Materials: • Computer or mobile device with Internet connectivity • Calculator Name: _________________________________________________ Period: ___________ Date: ________________ Mass Extinction Laboratory Activity – Teacher Edition 3. Make sure the timeline displays 0–540 million years and then click on “View” at the bottom of the screen; turn on “Mass Extinctions.” Click “View” again to minimize the menu. 4. Note the five yellow triangles that appear on the right side of the timeline. These correspond to mass extinctions. 5. Gather Data: Drag the slider to the Ordovician extinction, 440 MYA. Use the EarthViewer features to fill in the following chart. For Biodiversity, you will need to move the slider carefully and record the number of marine genera present just before and just after the extinction event. Gather data in the same manner for the remaining four mass extinctions. Mass Extinction Ordovician Devonian Permian Triassic Cretaceous What was Earth's surface like? Landmasses? Proportion of land to water? Few but huge landmasses; more water than land Huge landmass with surrounding bodies of water Biodiversity (# of Luminosity genera just before & just after extinction) Avg. Surface Temp., °C O2 (%) CO2 (ppm) Day Length 15.5 18.2 4746 21.8 hours 96.16 869 16.9 27.1 3497 22.2 96.82 1025 250 There are more landmasses than water 17.8 26.3 578 22.7 97.82 293 200 There are more landmasses than water 14.9 20.7 1391 23.0 98.24 520 65 More landmasses; scattered bodies of water 15.9 22.7 850 23.7 99.48 1357 MYA 440 365 Name: _________________________________________________ Period: ___________ Date: ________________ Mass Extinction Laboratory Activity – Teacher Edition Analysis: 1. Do any patterns and correlations emerge from your chart? If yes, describe this pattern. Yes. There is a noticeable low surface temperature, high carbon dioxide concentration and low levels of oxygen in each mass extinction. 2. Does any of the data suggest an explanation for the occurrence of mass extinction? Explain your answer. The low surface temperature could possibly indicate the beginning of glaciation period which makes it difficult for other organisms to survive. The low level of oxygen and high level of carbon dioxide also makes the environment toxic for organisms to survive. 3. Return to EarthViewer and click on each mass extinction to find out its cause. Based on the information you have gathered, how do mass extinctions occur? Mass extinctions occur when there are catastrophic events or when there is a drastic change in the environment.