Cenozoic K T mass extinction Flashcards
When does the Cretaceous come to an end?
Major extinction that is called the k T mass extinction
What does the K T mass extinction mark?
Loss of the dinosaurs and the rise of modern mammals
Large mammals dominate the land today
What happened 65 million years ago?
Asteroid landed on the yucatan peninsula creating an impact crater
Dust kicked up into the atmosphere and would have stopped all photosynthesis
Food chain collapses
What is the rate of plant growth called?
Productivity
Food chain
Plants —> herbivore —> Carnivore
Correlation between sunlight and photosynthesis with productivity
Decreasing sunlight decreases photosynthesis
What happened to larger dinosaurs?
Larger dinosaurs that were herbivores needed lots of vegetation to sustain their life, starved out quickly due to no plant life available
What does the K T / Cretaceous Tertiary boundary mark?
It marks the boundary between underlying dinosaur-bearing rock layers and overlying rocks
What was the evidence for impact of a meteorite?
Thin layer of the element iridium ONLY COMMON IN ASTEROIDS and METEORITES, not common on Earth
LUIS AND WALTER ALVAREZ
first to find it
Iridium spike marks the K T boundary
What happens when an asteroid impacts Earth?
Molten material is cast into the air and transported, cools quickly to form tektite
What can tektite form?
Unique shape from rotation, ejected magma forming spheres, dumbbells, and teardrops
What is also found at the boundary?
Shocked quartz, consists of quartz sand grains that have been catastrophically shattered
What is a good indication that photosynthesis had shut down during the K T boundary?
LACK OF CHALK
What takes over in the cenozoic?
BIRDS MAMMALS AND BONY FISH
