Chapter 21 - Paleozoic Life History

Question 1

What is the Cambrian explosion? When did it happen? date

Answer 1

Metaphor; all of a sudden had a huge variety of life forms that come on to planet

• 555-525 M.y ago
• all these species appeared at once

Question 2

What are cnidarians? When did they come?

Answer 2

Aquatic invertebrate animal of phylum Cnidaria

-suddenly appearing in fossil record in Cambrian explosion

Question 3

When were the first land plants on earth?date

Answer 3

about 470M.y ago - 444 M.y ago (spores)

Question 4

When did the major diversification of vascular plants start? date

Answer 4

416 M.y ago

Question 5

When did the first seeds start to grow? date

Answer 5

385 M.y ago

Question 6

When did reptiles first grow? What can we infer off this? period

Answer 6

Pennsylvanian (carboniferous) period

• can only live on land if theres something to eat, so there has to be land vegetation
• reptiles have the amniotic egg-egg with shell/yolk/egg white
• this makes evolutions of reptiles possible
• does not need water source to reproduce

Question 7

What period was the biggest for plant growth? period

Answer 7

Devonian period

Question 8

What are vascular plants? period

Answer 8

They have a tissue system of specialized cells for the movement of water and nutrients

Question 9

When were First amphibians on earth? How big are they period

Answer 9

middle to late Devonian

• first land vertebrates, amphibians
• ~1m long
• must go to the water to reproduce

Question 10

When were first spores on earth? (first land plants)

Answer 10

~470m.y years ago

Upper Ordovician period (first land plants)

Question 11

What are echinoderms?

Answer 11

starfish, sea urchin, etc..

-marine invertebrate of phylum echinodermata

Question 12

Most famous location for “Cambrian explosion” ? What is it the home of?

Answer 12

Burgess shale, Yoho national park, BC

• fossil deposit, so much evidence
• home of most famous quarry, “Walcott Quarry”. The quarry is the Unesco world heritage site

Question 13

Importnat Fossils from the burgess shale;

Answer 13

Hallucigenia (a velvet worm)
Opabina (predator)
Pikaia

Question 14

Cambrian marine community. Name an important wun, and say when it came?

Answer 14

Back then, almost all life was In the ocean
Land wasn’t colonized in the beginning
(Late) Cambrian marine diversity
-PIKAIA (Cambrian)

Question 15

Sulurian life diversity

Answer 15

started in silurian period:

Lobe finned fish

Question 16

Devonian marine life diversity

Answer 16

Reef growth

-make good oil reservoirs

Question 17

When was the age of fishes? date + period

Answer 17

415 to 355 m.y ago

-Devonian time

Question 18

Great moment in evolution for fish

Answer 18

Silurian period (lobe finned fish came) -> Devonian period(lobe-finned fish –> lung fish evolved)

• lobe finned fish evolved into lung fish in Devonian period
• elongated body and paired fins so they can move on land

Question 19

Devonian period wrt vegetation

Answer 19

Relatively sparse vegetation mostly hollow trunks

Question 20

Pennsylvanian period wrt vegetation

Answer 20

lush vegetation forming extensive coal swamps, solid trunks

-this is why reptiles can flourish on land, lots of vegetation for them to eat

Question 21

Adaptive radiations and mass extinctions through time

Answer 21

Cambrian explosion (600M.y ago) flourished with species
Then 250M.y Ago, late Permian period, greatest mass extinction of all time

Question 22

Adaptive radiation graph

Answer 22

Number of families (Y-axis) vs geologic time (million years, x-axis)

• positive slope means a lot of new life forms appearing, called adaptive radiations
• should know the geologic time scale, Cambrian ,o, s, d, carb, mperm, tri, jur, cret, tert, know these times

Question 23

% of species extinct in late Permian mass extinction?

Answer 23

94%

Question 24

Findings from rock record of information of late permain mass extinction; duration, an steps of the extinction

Answer 24

Duration of extinction ~ 10000

Steps of extinction:

1) First effected, land animals
2) Massive marine extinction
3) Massive land extinction

Question 25

Probable causes of mass extinction

Answer 25

Supercontinent (Pangea) –> superplume, loading atmosphere with CO2 —> Heating —-> CH4-hydrate melting —-> heating + O2 depletion