Geological history of earth Flashcards
(26 cards)
What is the Phanerozoic Eon?
It means “visible life” and marks when most major life forms appeared
what are the periods of time?
Cambrian - Clever
Ordovician - Old
Silurian - Scientists
Devonian - Discover
Carboniferous - Cool
Permian - Plants
Triassic - That
Jurassic - Just
Cretaceous - Changed
What causes planetary environmental changes?
- Solar output
- Tilting of the planet
- Changes in elliptical orbits
- Quantity of carbon dioxide, methane and water vapour in the atmosphere.
- Ability of ocean to absorb Co2
- Plate tectonics
- Volcanoes
- Ocean currents
- Human beings.
What were microbial reefs made of and by whom?
Made of cyanobacteria, forming stromatolites
What was Earth’s oxygen level before cyanobacteria?
Around 1%
Why did oxygenation cause a mass extinction?
Oxygen was toxic to anaerobic organisms, leading to their decline
What is the significance of aerobic metabolism?
Enabled evolution of multicellular life
What happened during Snowball Earth (~717 MYA)?
Glaciers melted, releasing nutrients and fueling plankton/algae growth
What is significant about the Ediacaran era?
First large, complex multicellular soft-bodied organisms appeared
What occurred during the Cambrian Period?
Cambrian Explosion—appearance of major animal phyla
What was the GOBE and when did it occur?
Great Ordovician Biodiversification Event—Ordovician Period (495–444 Mya)
What key life form first appeared in the Devonian?
Amphibians on land
Why is the Carboniferous Period important?
Major coal deposits formed; life dominated by crinoids
What happened to lignin degradation after the Carboniferous?
White rot fungi evolved the ability to break it down
What caused the Permian mass extinction?
Massive volcanic activity, acid rain, possible asteroid impact
What is the “Age of Dinosaurs”?
The Mesozoic Era: Triassic, Jurassic, and Cretaceous
What key evolution occurred in the Triassic?
Synapsids developed erect stance and warm-bloodedness
What caused the end-Cretaceous extinction?
An asteroid impact, wiping out ~75% of species including non-avian dinosaurs
What is significant about the Cenozoic?
Radiation of mammals and flowering plants, emergence of hominins
What question arises in the Holocene epoch?
Are we currently in the sixth mass extinction?
when were the five major extinction events?
- End-Ordovician Extinction (~444 million years ago)
- Late Devonian Extinction (~375–359 million years ago)
- End-Permian Extinction (~252 million years ago)
- End-Triassic Extinction (~201 million years ago)
- End-Cretaceous Extinction (~66 million years ago)
what was the cause and level of loss of the End-Ordovician Extinction?
Loss: ~85% of marine species
Cause: Rapid climate cooling and glaciation, falling sea levels
what was the cause and level of loss of the Late Devonian Extinction?
Loss: ~75% of species
Cause: Anoxia (low oxygen in oceans), possible asteroid impact, climate change
what was the cause and level of loss of the End-Permian Extinction?
Loss: ~90–96% of all species
Cause: Massive volcanism (Siberian Traps), global warming, ocean acidification, methane release
