SCIENCE9-Mass Extinction,TYPES OF MASS EXTINCTION.pptx

MASS EXTINCTION

1. Mass Extinction

2. E xtinction means that the last identified individual of the species has been extinguished or no longer existing permanently. There are five major extinctions that existed million years ago. These are the Ordovician, Devonian, Permian, Triassic, and Cretaceous extinction.

3. Types of Extinction Mass Extinction Mass extinction means that a catastrophic event (e.g., asteroid hitting Earth, massive volcanic eruption) has decimated life on Earth.

4. Mass Extinction 1. Ordovician extinction 440 million years ago (MYA). The temperature is fluctuating because of the two main phases during this time G laciation the decline of CO 2 , resulted in global cooling and glacial formation. Sea levels eventually dropped, decreasing habitat. Heating events Then global warming and sea level rising came. Organisms that were once adapted to a cooler climate vanished due to the increase in temperature.

5. 2. Devonian extinction the next mass extinction that happened 365 MYA . During this period, land plants developed deep roots that released nutrients in the ocean. These nutrients caused the algae in the ocean to flourish. This algal bloom depleted the oxygen in the ocean that was necessary for the survival of other marine animals. Another theory suggests that another global cooling and sea level falling events occurred, which led to habitat loss.

6. 3. Permian extinction 252 MYA . This mass extinction is considered the deadliest because 96% of life back then was lost. A massive volcanic activity in Siberia caused huge amounts of sulfur dioxide (SO₂) and CO 2 to be released. Huge quantities of these gases led to acid rain, ocean acidification , and global warming .

7. 4. Triassic extinction fourth mass extinction 201 MYA . One theory suggests that tons of CO 2 were in the atmosphere due to volcanic eruptions . This resulted in global warming and ocean acidification. Roughly 80% of life was lost including most mammals, paving the way for the dinosaur's ancestors.

8. 5. Cretaceous extinction which occurred 66 MYA . According to theories, an asteroid hit Earth in the Yucatan Peninsula, Mexico, and wiped out all dinosaurs along with roughly 60% of all life on Earth. The impact released abundant debris in the atmosphere, leading to a brief superheating event followed by rapid cooling.

9. Modern Day Extinction Environmental factors that occurred in the past still exist today. Ocean acidification, global warming, and sea level rising occur because of increased CO 2 levels due to human activities such as burning of fossil fuels, farming , and deforestation . Algal blooms decrease the levels of oxygen in oceans and lakes. As a whole, the reduced biodiversity is associated with anthropogenic or human activities.