Geologicam Time Scale Amd Extiction Flashcards
Based of fossil evidence, when did life first evolve?
3,4 billion years ago
What are the names of the eras in the Phanerozoic eon and what are there defining dates.
Paleozoic: 542-251 mya
Mesozoic- 251-65.5 mya
Cenozoic- 65.5 to present day
What is the difference between background and mass Extiction?
Background- low scale, continuous, due to biological factors, dosent leave an ecological void.
Mass- fast(5-10mya) leaves ecological void, due to catastrophic events.
Which type of extinction is thought to have caused the lost extinctions over evolutionary time?
Background extictio
How many mass extinctions have been recorded in earths history, not including the one we’re currently in?
Which has th largest number of extinct species?
5
End Permian- 95% of all organisms
What are the dates of the Permian and end Cretaceous mass extinctions? And what are the ears and periods they separate?
Permian- 251mya. Permian and Triassic . Paleozoic and Mesozoic.
KT- 65.5mya. Cretaceous and Paleogene. Mesozoic amd Cenozoic.
In general, what causes background extinction?
Biological factors- predation, competition, parasitism
What causes mass Extiction?
Catastrophic events- extreme volcanism, extraterrestrial impact,
What do experts believe was the cause of the end Cretaceous Extiction?
A large asteroid hit the earth causing sulfuric acid aerosols to cloud the sky, blocking out sunlight for years, killing all photosynthetic plankton and plants, causing the collapse of the food chain. Global fire storms, mega tsunami, global cooling and then global warming.
What are most well supported hypothesis about the Permian Extiction,
Three things at once- extreme volcanism, asteroid impact and anoxia of the oceans. Asteroid and volcanism same as KT. Anoxia- ocean would become stagnant due to lack of polar ice caps, bicarbonate could build up, leading to a decrease in O2 and turning the ocean to soda water killing marine life
What is adaptive radiation. How does it come into play following an Extiction?
Organisms diversify rapidly into new for,s when there is an extreme change in environment leaving ecological voids and niches such as those following a mass extiction
