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Flashcards in Chapter 15 Deck (42):
1

define extinction

all individuals in that species/genus/etc. have died out and left no descendants

2

dissolution

water dissolves fossil leaving behind a cast

3

carbonization

thin carbonized layer

4

What are the right conditions fossilization requires?

Geological and abiotic conditions.
Most often occurs in sedimentary rocks

5

What factors can disrupt the process of fossilization?

scavengers/predators
soft tissue preservation rare
abiotic factors break down organism

6

Lagerstatten (resting place)

Large number of fossils found together due to perfect geological and biotic conditions

7

Ediacaran fossils

Huge burst of new multicellular organisms

8

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

9

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

10

Radiocarbon dating (absolute aging)

Isotope carbon-14 decays into carbon-12 at a steady state, half-life 5730 years.

11

Potassium-14 to argon-40

(1.3 by half-life), volcanic in origin; date surrounding volcanic rocks around fossil

12

Paleomagnetic dating

Changes in the earth's magnetic field which is preserved in metal grains in rocks.

13

Does a fossil represent the first or last appearance of the species?

NO

14

Signore-Lipps effect

Time lag between the last known fossil and extinction;
result= extinction date is estimated to be earlier that it actually is

15

"Forward smearing"

reworking of strata; mixing of layers

16

Mass extinctions

Spike in extinction rates; 40-50% of all species & 5-8 in earth's history

17

Background extinction

extinction outside of mass extinction, 95% of all extinctions

18

How is background extinction caused?

Mainly caused by predation, competition, diseases, climate change.

19

endemic

native to only one area

20

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

21

What can happen if new predators enter an area (natural or unnatural)?

Can extirpate native fauna

22

What are the 5 big mass extinctions?

Ordovician, Devonian, Permian, Triassic, Cretaceous (K-T)

23

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

24

What are the 4 causes of loss in mass extinctions?

taxonomic diversity, morphological diversity, behavioral diversity, number of different types of niches

25

Dead clade walking

Clade that survives a mass extinction event to only going extinct in the next geological time period

26

K-T Mass Extinction aka Cretaceous-Tertiary

Occurred over very short period of time; supernova/ asteroid collision theories (iridium deposits)

27

Permian Extinction

Greatest mass extinction, all walks of life hit hard, coral reefs depleted

28

What caused Permian extinction?

Siberian traps- huge volcanic eruptions &
massive "greenhouse" effect due to CO2 release, so surviving species adapted to hypoxia

29

How come species longevity has no effect on the probability of extinction

Extinction is a function of how well individuals in a species adapt to the current environment, not how well they adapted to past conditions

30

What is the advantage of having a broader geographic range?

The less likely a taxon will go extinct

31

Phyletic gradualism model

Adaptations that arise within a species are the result of slow gradual processes, where any variant that provides the slightest benefit slowly increases in frequency
ex. equine evolution

32

cladogenesis

a new form that appears in the fossil record arising through branching speciation events

33

anagenesis

a new form that appears in the fossil record arising through gradual modification WITHOUT branching speciation

34

Punctuated equilibrium

predicts that a lot of evolutionary change takes place in short periods of time tied to speciation events
ex. Cambrian explosion

35

Cambrian explosion (5 facts)?

-543-490 mya spike in number of species
-new body forms and shapes
most of the animal groups that have ever lived can be traced back to this time period

36

What is Punctuated equilibrium in bryozoans tied to?

tied to changes in oceanic boundaries

37

Cope's rule

Species in mammalian clades tend to increase in body size over evolutionary time. (Doesn't always hold up within mammals and across other groups)
*general increase in organismal complexity*

38

What is the difference between passive & active trends?

Passive: no directional tendency to change, but the precursor starts at a minimum size which evo can't take new lineages
Active: each lineage tends to increase in body size

39

What two processes lead to active trends?

-trait values with each subclade shifting in parallel
-species selection

40

Species selection

speciation and extinction rates that vary according to the value of the trait in question

41

In what body size does speciation events take place more frequently?

Speciation events are more frequent among LARGER species

42

Tree branches are longer in larger species, what does this indicate?

Fewer extinctions