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Geology F795 > Microfossils > Flashcards

Flashcards in Microfossils Deck (17):
1

Why are microfossils useful?

Can be used to correlate rocks, well preserved and show strong evolutionary trends

2

What are Ostracods?

Complex crutaceans, two valves with teeth and sockets, car pace shell of chitin are calcite

3

Range of Ostracods?

Cambrian to present

4

How can ostracod fossils be used?

Long statigraphic range which limits use as zone fossil, paleoenvironment indicators as have different forms in water of different salinity

5

What are Forminfera?

Single called creatures, protective test, early forms glued together, feed via thread like structures, most Benthonic

6

Time range of Forminfera

Cambrian to present

7

How can Forminfera be used?

Stratigraphic tool used extensively in oil industry, detailed ranges can be determined for differ species, provide evidence for evolution

8

What are conodonts?

Teeth of soft bodies creature, calcium phosphate, occur in pairs, found in Precambrian ricks to Permo-Triassic extinction

9

What are Radiolaria?

Marine, planktonic organism, composed of silica, occupy niches near surface to hundred of m depths, rich diversity, preserved below CDC

10

Range of radiolaria?

Precambrian to present

11

How are spores and pollen preserved?

Tough, composed of sporopollenin, found from Ordovician onwards, pollen from late Devonian. Produced by plants in land or in shallow water, washed out to sea so found in lots of environments

12

How does evolution occur?

Phyletic gradualism, characteristics change by mutation and cross breeding, favoured by natural selection

13

What is gradualism?

Gradual evolutionary change over time, creation of new characteristics it genes

14

What is genetic drift?

Few selective pressures, random sampling of parent genotype can eventually lead to elimination of some characteristics

15

What is gene flow?

Exchange of genes between populations by migration or pollination

16

What is punctuated equilibrium?

For long periods no change occurs as population expands, at limits of environment, population forced to adapt and new species takes over quickly

17

Why are microfossils better for proving evolution than microfossils?

Small and abundant in rocks, tend to be better preserved