Chapter 15 Flashcards
define extinction
all individuals in that species/genus/etc. have died out and left no descendants
dissolution
water dissolves fossil leaving behind a cast
carbonization
thin carbonized layer
What are the right conditions fossilization requires?
Geological and abiotic conditions.
Most often occurs in sedimentary rocks
What factors can disrupt the process of fossilization?
scavengers/predators
soft tissue preservation rare
abiotic factors break down organism
Lagerstatten (resting place)
Large number of fossils found together due to perfect geological and biotic conditions
Ediacaran fossils
Huge burst of new multicellular organisms
Where do you look for fossils?
Look for sites that are prone to have fossils based of ideal geological and abiotic conditions
Look near previously identified sites
phylogenetic/ biogeographical reconstructions
combinations of above
Law of superposition (relative aging)
Fossils found lower down in the sediment at a particular locality are older than those found closer to the surface
Radiocarbon dating (absolute aging)
Isotope carbon-14 decays into carbon-12 at a steady state, half-life 5730 years.
Potassium-14 to argon-40
(1.3 by half-life), volcanic in origin; date surrounding volcanic rocks around fossil
Paleomagnetic dating
Changes in the earth’s magnetic field which is preserved in metal grains in rocks.
Does a fossil represent the first or last appearance of the species?
NO
Signore-Lipps effect
Time lag between the last known fossil and extinction;
result= extinction date is estimated to be earlier that it actually is
“Forward smearing”
reworking of strata; mixing of layers
Mass extinctions
Spike in extinction rates; 40-50% of all species & 5-8 in earth’s history
Background extinction
extinction outside of mass extinction, 95% of all extinctions
How is background extinction caused?
Mainly caused by predation, competition, diseases, climate change.
endemic
native to only one area
What can happen if natural selection favors traits in predators that make them efficient at capturing prey?
Can cause prey to go extinct; also cause an evolutionary arms race
What can happen if new predators enter an area (natural or unnatural)?
Can extirpate native fauna
What are the 5 big mass extinctions?
Ordovician, Devonian, Permian, Triassic, Cretaceous (K-T)
How is extinction a double-edged sword?
Besides wiping out lineages and genetic variation, the evolutionary landscape changes opening up new opportunities for surviving lineages
What are the 4 causes of loss in mass extinctions?
taxonomic diversity, morphological diversity, behavioral diversity, number of different types of niches