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

Question 1

Devonian saw…

Answer 1

plants develop from low herbs to woody trees

Question 2

Archaeopteris

Answer 2

~10m high: first forests

Question 3

when did woody trees die out?

Answer 3

At Devonian/ Carboniferous boundary

Question 4

Forests did not re-establish until

Answer 4

Mid Carboniferous

Question 5

In late Devonian, landmasses were…

Answer 5

southerly, arid

Question 6

By Carboniferous the landmasses had moved towards

Answer 6

the Equator & had become tropical and humid

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

Question 7

Plants were causing…

Answer 7

the climate to change…

Question 8

Vast lowland coastal areas became

Answer 8

vegetated

Question 9

plants (+ lignin + charcoal) were locking up

Answer 9

CO2atm as Corg

Question 10

By mid Carboniferous
what plummeted?
what soared?

Answer 10

CO2atm plummeted, and O2atm soared

glaciation: Sn. polar ice cap

Question 11

Carboniferous =

Answer 11

“Coal bearing”

Question 12

Sea-level dropped and so exposed more…

Answer 12

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

Question 13

‘swamp’ =

Answer 13

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

Question 14

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

Answer 14

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

Question 15

Rajang Delta in Sarawak (Borneo)

Answer 15

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

Question 16

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

Answer 16

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

Question 17

Carboniferous, erroneously called the “Age of Ferns”

Answer 17

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

Question 18

More like the “Age of Seed-ferns”

pteridosperms or seed-ferns

Answer 18

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

Question 19

Spore-producing plants

Answer 19

modern horsetails <4 m high

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

Question 20

Carboniferous ‘trees’ often found preserved where they grew

Answer 20

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

Question 21

Giant club mosses: ‘scale trees’

Arborescent lycopod Lepidodendron

Answer 21

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

Question 22

Going hetero…

reproductive organs in a cone

Answer 22

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

Question 23

A new form of plant sex

Answer 23

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

Question 24

Sea ‘scorpions’

Answer 24

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

Question 25

The Giant Claws

Answer 25

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

Question 26

Massive myriapods

Answer 26

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?

Question 27

Giant dragonflies: Meganeura

Answer 27

Patterned wings, 75 cm wingspan

Today a short lived part of the life cycle

Question 28

‘Roaches…

Answer 28

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