Mass Extinctions

• What was the most devasting extinction event?

  Permian-Triassic Extinction
• Continents were joined together as the supercontinent Pangea

  •Large Panthalassa (ancient Pacific) Ocean and the Tethys Ocean

  •Vast deserts covered western Pangea during the Permian as reptiles spread across the face of the supercontinent.
• What group of organisms were most affected by the Permian-Triassic extinction?

  Marine organisms
• Trilobites - Segmented animals with exoskeleton composed of chitin or calcium carbonate, with jointed limbs and became fully extinct at the P-T
• Siberian traps - were formed by the largest volcanic event in history which coincides with the P-T extinctions
• The flood basalts of the Siberian traps were produced by what giant pulse of heat that rises to the surface from the core-mantle boundary?

  Mantle plume
• What were the major factors that lead to the Permian-Triassic Extinction?

  Volcanic Activity, Climate Change
• Buckyballs - 60 carbon atoms arranged in a hollow sphere and researchers believed that these are extraterrestrial because the gases trapped inside have an unusual ratio of isotopes that indicate they were made in the atmosphere of a star that exploded before our Sun was born.
• Pleistocene extinction - Different from the K-T and P-T extinctions in that it primarily affected large (i.e. more than 44 kg) terrestrial mammals.
• The La Brea Tar Pits in the middle of the City of Los Angeles, California contains one of the most well-preserved Pleistocene fossil sites in the world.
• Tar Pits - form when crude oil seeps to the surface through fissures in the Earth's crust; the light fraction of the oil evaporates, leaving behind the heavy tar, or asphalt, in sticky pools.
• What is are the possible causes of the Pleistocene extinction?

  Human overpredation, Climate change
• During the overkill hypothesis, who were the first to enter the new world to easily kill large animals?

  Clovis people
• The last expansion of the polar ice sheets took place about how many years ago?

  18000
• Wallace's Line - represents a distinct faunal separation between the landmasses of mainland Asia and Australia.

  
• What does the Bering land bridge connect?

  Asia and North America