Lecture 11: The Carboniferous Massive: the great coal swamps. Flashcards Preview

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Flashcards in Lecture 11: The Carboniferous Massive: the great coal swamps. Deck (28)
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1
Q

Devonian saw…

A

plants develop from low herbs to woody trees

2
Q

Archaeopteris

A

~10m high: first forests

3
Q

when did woody trees die out?

A

At Devonian/ Carboniferous boundary

4
Q

Forests did not re-establish until

A

Mid Carboniferous

5
Q

In late Devonian, landmasses were…

A

southerly, arid

6
Q

By Carboniferous the landmasses had moved towards

A

the Equator & had become tropical and humid

vast thicknesses of warm water limestones (e.g. Carboniferous Limestones of Peak District, Cheddar Gorge, etc.)

7
Q

Plants were causing…

A

the climate to change…

8
Q

Vast lowland coastal areas became

A

vegetated

9
Q

plants (+ lignin + charcoal) were locking up

A

CO2atm as Corg

10
Q

By mid Carboniferous
what plummeted?
what soared?

A

CO2atm plummeted, and O2atm soared

glaciation: Sn. polar ice cap

11
Q

Carboniferous =

A

“Coal bearing”

12
Q

Sea-level dropped and so exposed more…

A

lowland areas for plants to colonise
plant material became preserved in the rock record as coal
‘Coal Measures’ have been exploited for ~400 yrs

13
Q

‘swamp’ =

A

lowland containing woody plants, fed by groundwater (e.g., rivers)

14
Q

Coal can’t be produced in delta-top swamps as…

A

Too little organic carbon (‘peat’) can build up to produce the thickness of coal seen in the Carboniferous

Rivers switch channels laterally: cover swamps with sediment before enough peat can build up

15
Q

Rajang Delta in Sarawak (Borneo)

A

Huge thicknesses of organic matter build up in raised mires, built up above the land/water table level
Wet conditions due to rainfall, not river supply (‘ombrotrophic – rain-fed - mires’)
More peat built up during Carboniferous glacial phases (than in interglacials)
Rivers incised and sediment load bypasses mires

16
Q

Plants produce many different organs throughout their lifespans
Organs separate during life and death
Each organ can be found as

A

An individual fossil
Fossil organs from an individual plant have different generic names
One plant is represented by several “form genera”

17
Q

Carboniferous, erroneously called the “Age of Ferns”

A

actually relatively low fern diversity in Carboniferous
ferns: pteridophytes
reproduce using spores
still homosporous

18
Q

More like the “Age of Seed-ferns”

pteridosperms or seed-ferns

A

fern-like foliage
no wood: held up by interwoven roots & leaf bases
Alethopteris / Neuropteris
maximum 10 m in height

19
Q

Spore-producing plants

A

modern horsetails <4 m high

in Carboniferous reached arborescent (tree-like) size: up to 20 m (60 ft) tall…

20
Q

Carboniferous ‘trees’ often found preserved where they grew

A

e.g., Fossil Grove, Glasgow
10 trunk/root systems, rotted in life position & filled with sand
lycopods

21
Q

Giant club mosses: ‘scale trees’

Arborescent lycopod Lepidodendron

A
Thick bark covered in ‘leaf’ scars
root: Stigmaria
‘leaf’ scale: Lepidophyllum
reproductive cone: Lepidostrobus
up to 54 m (180 ft) high
22
Q

Going hetero…

reproductive organs in a cone

A
Produced separate male and female reproductive structures
♀ megaspores at bottom
♂ microspores at top
heterospory
could cross- and self-fertilise
23
Q

A new form of plant sex

A

no. of megaspores reduce, not shed, retained on plant
♂ spores become modified into ♂ pollen
pollen fertilizes megaspore, produces a seed (<10 cm in size)
fleshy outside: food source
animals eat, excrete, disperse seeds

24
Q

Sea ‘scorpions’

A

some probably amphibious
freshwater by late Carboniferous
no evidence for venom, but predatory

25
Q

The Giant Claws

A

Silurian: Mixopterus
40 cm, freshwater aquatic and terrestrial
Silurian: Pterygotus - 2.3 m
Devonian: Jaekelopterus – 2.5 m long

26
Q

Massive myriapods

A
palaeodictyoptera: extinct insects 
bold colour patterns
up to 55cm wingspan
piercing, sucking mouthparts
were complex structures on new seeds to guard the ovule against insects?
27
Q

Giant dragonflies: Meganeura

A

Patterned wings, 75 cm wingspan

Today a short lived part of the life cycle

28
Q

‘Roaches…

A

cockroaches
little changed since Carboniferous
but rather larger in size at 9cm!