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Evolution__3rd_Edition

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654 PART 5 / Macroevolution<br />

10 6 years<br />

Q<br />

T<br />

65<br />

K<br />

144<br />

J<br />

213<br />

Tr<br />

248<br />

P<br />

286<br />

C<br />

360<br />

D<br />

408<br />

S<br />

438<br />

O<br />

505<br />

Ca<br />

545<br />

V<br />

Global events Extinction (% genera) Sea level<br />

5%<br />

60%<br />

% flooded<br />

central N. America<br />

craton<br />

Flood-basalt<br />

volcanism<br />

(since late Permian)<br />

Minimum area of<br />

coverage, km 2<br />

20 40 60 4 5 6<br />

Figure 23.5<br />

Summary of extinction events and the incidence of possible<br />

causes of these extinction events. Evidence is shown for:<br />

extinction rates (both as “global events” in which the bar width<br />

represents the magnitude of the extinction events, and as<br />

Columbia River (USA)<br />

Ethiopian<br />

Brito-Arctic<br />

Deccan (India)<br />

Rajmaha (India)<br />

Serra Geral (S. America)<br />

South-West Africa<br />

Antarctica<br />

South Africa<br />

E. North America<br />

Siberia<br />

Plate tectonics Impact structures<br />

Tethys closed<br />

Laurasia dispersed<br />

North Atlantic opened<br />

Gondwana dispersed<br />

Central Atlantic opened<br />

South Atlantic opened<br />

Tethys opened<br />

Dispersal of Pangaea<br />

PANGAEA<br />

Central lapetus closed<br />

North Atlantic closed<br />

Assemblage of<br />

Laurentia +<br />

Fennosarmatia<br />

Iapetus opened<br />

RODINIA<br />

high levels of volcanic eruptions, and changes in the shape of continents due to plate<br />

tectonic movements. Several periods of elevated extinction rates are associated with<br />

changes in sea level. Falls in sea level reduce the habitat available for marine life, driving<br />

species extinct. Changes in sea level will also be correlated with changes in climate. The<br />

combined influence of climate and sea level is widely thought to have contributed to<br />

some mass extinctions. However, sea level changes also occur at times when there is no<br />

Caledonian–Variscan megacycle Alpine megacycle<br />

79<br />

33 Piles<br />

Poplga<br />

64 75<br />

105 54 44<br />

Kara<br />

43<br />

95<br />

9<br />

15<br />

30<br />

59<br />

80 76<br />

84<br />

17 18<br />

16<br />

58<br />

90<br />

Sillan<br />

91<br />

97<br />

Chicxulub<br />

structure<br />

Puchezh-<br />

Kalungi<br />

Manicouagan<br />

Diameter (km)<br />

20–29<br />

30–39<br />

40–49<br />

ranges<br />

50–79<br />

80–100 Age<br />

percentage rates, similar to Figure 23.2), sea levels, volcanic<br />

activity, plate tectonics, and asteroid impacts. The date of the<br />

end-Triassic volcanic rock has been updated from the source.<br />

(10 miles = 16 km.) Modified, by permission of the publisher,<br />

from Morrow et al. (1996).<br />

..

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