Extinction Flashcards
What are the two types of extinction?
Contemporary
Geological
Give some examples of contemporary extinction
Local extinction
Species extinction
Give some examples of geological extinction
Background extinction
Extinction events
Mass extinction events
How many species are threatened with extinction?
25% of species
What percentage of all species that have ever existed have gone extinct?
99%
What are the types of extinction in the fossil record?
Background extinction - the sum of all normal species terminations during a defined time interval
Extinction events - times when many species go extinct for a shared reason, typically regional
Mass extinction events - times of gelogically rapid global disappearance of most life (many species of wide ecological range died out worldwide)
What was the End-Ordovician mass extinction?
444 million years ago
Declines in nautiloids, trilobites, brachiopods, crinoids, bryozoans and corals
Due to major glaciation event
What was the Late Devonian mass extinction event?
372 million years ago
Declines in trilobites, brachiopods, bivalves, corals, sponges, fishes
Complete loss of ostracoderms and placoderms
Due to large igneous province and ocean anoxia
What was the End-Permian mass extinction event?
252 million years ago
Declines in brachiopods, synapsids
Complete loss of blastoids and trilobites
Due to large igneous provinces and ocean anoxia
What was the End-Triassic mass extinction event?
201 million years ago
Declines in bivalves and gastropods
Complete loss of conodonts and basal archosaurus
Due to large igneous provinces and ocean anoxia
What was the End-Cretaceous mass extinction event?
66 million years ago
Declines in bivalves and gastropods
Complete loss in dinosaurs, pterosaurs, plesiosaurus, mosasaurs, ammonites and belemnites
Due to meteorite impact and large igneous provinces
What do survivors of mass extinction events often share?
Generalist characteristics
What is orthogenesis?
Change in organisms was due not to natural selection but to unchecked directional trends within a lineage
What is a supposed ‘example’ of orthogenesis?
Irish elk
Became extinct when antlers became too large as could no longer hold up their heads and antlers got tangled in trees
No evidence this actually happened
What is the Red Queen and the Court Jester thoery?
Suggests an arms race between organisms
Red queen is for biotic factors
Court Jester is for unpredictability like geographical changes
