history of biodiversity

Question 1

precambian

Answer 1

’ before life ‘

period of time extending from about 4.6 billion years ago ( the point at which earth began to form )

Question 2

age of earth

Answer 2

4.5 bya ( billion years ago )

Question 3

earliest living organisms

Answer 3

Carbonacous chert clast
3465 mya
apex filament microfossils present in altered hydrothermal vent deposit
5 taxa - photosynthesises and methane producers

Question 4

ealiest animal

Answer 4

’ worm ‘ 550 mya

ancient steriods indicate it is an animal

Question 5

garden of Ediacara

Answer 5

earliest animals

• strange shapes sheet/leaf like
• soft bodies
• ( most ) no mouth or gut. must contain photsynthetic algae
• adapted to low oxygen levels? ( 7% - 10% of present day )

Question 6

garden of ediacara : views ( earliest animals )

Answer 6

tradititonal view : ancestors of present day animals

Seilacher’s view : early failed experiment , no descendents

Question 7

cambrian explosion

Answer 7

• 550 mya sudden apperaence of all major groups
• first animals with hard parts
• all major phyla ( excepy velvet worms )

Question 8

why diversification now ?

Answer 8

1. continents breaking up ( increased area of continental shelf - apperance of shallow sea - new habitats )
2. climate ( much warmer than today ? critical oxygen level ? )
3. developmental genetic and origin of major phyla ( development or mutation of single Hox gene - huge morphological change. mechanisms for initial rapid eveolution of body parts )

Question 9

Burgess Shale fauna

Answer 9

discovered - Walcott 1910s
‘ rediscovered ‘ - Whittington 1960s

• typical of cambrian faunas
• many soft bodied forms

most commom species triolbite marrella

(dominant group now and then = arthropods?)

Question 10

Cambrian (Cm) - pattern

Answer 10

start: huge radiation major groups appear

end: stabilization of many of new groups
- little ecological stabilization

(about 542 mya - 490 mya)

• paleozoic

Question 11

Cambrian (Cm) - events

Answer 11

apperance of all major groups including jawless fish and marine ‘plants’ (algae)

Question 12

Ordovician (O) - Permian (P) - pattern

Answer 12

Ordovician (O) - Silurian (S) - Devonian (D) - Carboniferous (C) - Permian (P)

huge increase in biodiversity. then stable for 1/4 billion years. little ecological specilisation in the sea

( about 490 mya - 300 mya )

• paleozoic

Question 13

Ordovician (O) - Permian (P) - events

Answer 13

Ordovician (O)
- apperance of jawed fish ( cartilaginous and bony )

Silurian (S)
- first land plants

Devonian (D)
- ‘age of fish’ first amphibians. earliest insects

Carboniferous (C)
- huge terrestrial forests dominate. first reptiles

Question 14

Permian (P) - pattern

Answer 14

ended with largest biodiversity crash known. end of paleozoic ‘early life’

(about 300 mya - 250 mya )

• paleozoic

Question 15

Permian (P) - events

Answer 15

apperance of mammal-like reptiles

extinction of trilobites (group of arthropods)

Question 16

Triassic (T) - Cretaceous (K) - pattern

Answer 16

Triassic (T) - Jurassic (J) - Cretaceous (K)

started with largest biodiversity crash known. begininng of mesozoic (‘middle life’). rebirth of marine biodiversity but with very different forms that increase (with blips) to prsent day

(about 250 mya to 65 mya)

*mesozoic

Question 17

Triassic (T) - Cretaceous (K) - events

Answer 17

Triassic (T)

• marine : expansion of shell breaking predators + distruptive sediment movers. beginning of the ‘rule’ of marine mammals
• terrestrial : beginning of the rule of reptails ( + dinos )

Jurassic (J)
- age of ruling reptiles

Cretaceous (K)

• extinction of ichthyosaurs, plesiosaurs, mesosaurs and ammonites
• extinction of dinos and flying reptiles

Question 18

Paleogene (Pg) - Quaternary (Q) - pattern

Answer 18

Paleogene (Pg) - Neogene (N) - Quaternary (Q)

beginning of the 3rd era - the cenozoic. Biodiversity continues to increse exponentially (with small blips)

(about 65 mya to now)

*cenozoic

Question 19

Paleogene (Pg) - Quaternary (Q) - events

Answer 19

Paleogene (Pg)
- beginning of the age of mammals and flowering plants (angiosperms) on land

Neogene (N) and Quaternary (Q)
- age of insects, molluscs, fish (again) and one particular mammal

(Antropocene (A) an age of human influence and unprecedented biodiversity decline)

Question 20

mass extinctions

Answer 20

5 big ones

end ordovician, late denovian, end paleozoic, end triasssic, K-T

Question 21

background extinction rate

Answer 21

the number of species that would be expected to go extinct over a period of time, based on non-anthropogenic factors

(account for 96% of all extincrions over the past 600 mya)