L6- Carboniferous Terrestrial Ecosystems

LOs:

  • the carboniferous world

  • carboniferous plants and the beginnings of phytogeographical differentiation

  • fish recover from the Devonian mass extinctions

  • arthropods take to the air

  • more amphibians and the first reptiles

  • animals attack the plants (the beginnings of herbivory)

  • late Carboniferous global climate change

The Carboniferous World:

  • gondwana smashed into euramerica, pushed everything northwards, all the sediment in the ocean builds up into a mountain range, there is a massive ocean (panthalassic ocean) around the back of the world- can walk from top to bottom of the world

  • early C→ a little sea between euramerica and gondwana, massive ice sheet starts to develop on the south pole

  • late C→ sea closes up, mountain range forms

  • shifting from a greenhouse world in the silurian and devonian to an icehouse world in the carboniferous

    • caused by lowest CO2 levels and highest O2 levels

    • high O2 causes lots of forest fires and insect gigantism

    • icehouse world lasts for 80million years (Carboniferous-Permian)

Plants:

  • all plants evolved in the Devonian (except Angiosperms)

  • Bryophytes

    • lived in permanently damp areas, on rocks, as epiphytes on trees

  • Lycopsids

    • formed huge trees, dominated forests

  • Ferns

    • had herbaceous forms and tree forms

  • Sphenopsids

    • get different forms e.g. tree-like, lianas

    • is the same as equisetum (horsetail plants) but an order of magnitude bigger

  • Pteridosperms

    • first seed plants, appeared at the end of the Devonian, diversified in the Carboniferous

    • different forms, all produce primitive seeds→ live in dry environments

  • Cordaites/Primitive Conifers

    • new group in the late Carboniferous

    • are trees, seed plants strap-like long leaves

    • are primitive conifers

  • Early C→ map of different biomes:

    • there is a latitudinal gradient that forms different biomes of plants

    • ice sheet compresses the temperature gradient

    • get tropical rainforests across equator

    • there are the same plants in different biomes, but just different species

      → phytogeographical differentiation

  • Late C→ map of different biomes:

    • huge ice sheet

    • tropical everwet→ get coal measure rainforests at the equator, take out all the carbon in the atmosphere, have the most biomass ever, are dominated by lycopsids

  • plants across the carboniferous:

  • reconstruction of a coal measures forest at the equator:

    • trees, giant insects (due to high O2)

Invertebrates:

  • worms, scorpions, snails become terrestrial

  • first woodlouse relative appears

  • hexapods develop wings for the first time (main type of arthropod)

  • get insect gigantism e.g. Arthropleura arthropod (due to high O2 levels)

Fish:

  • end Devonian mass extinction wiped out most of the agnathans and all the placoderms

  • chondrichthyes and acanthodians start to diversify (relatives of sharks)

  • ray-finned fish are dominant today and lobe-finned fish are rare but in the Carboniferous this was the opposite

  • tetrapods evolve from the lobe-finned fish (sarcopterygii)

    → fish recover from the mass extinction but there is a change in the nature of fish biotas

Tetrapods:

  • End Devonian→ icthyostega is found in Greenland (mostly aquatic), get Romer’s gap that is being filled up

  • Carboniferous→ get diversification of different types of basal tetrapods, big branching points

    → there was a phylogenetically broad diversification where most basal tetrapod groups appeared quickly, all in the Carboniferous

  • transect of a deposit in Czech Republic:

    • get different basal tetrapods in these different environments

    • there are secondary aquatic organisms→ go back into sea

    • worked out food chain

  • reconstruction→ some tetrapods go back into the water, some are very big

Reptiles:

  • macroevolutionary event

  • most primitive reptiles evolved in the Carboniferous

    • produced eggs, have scales, eat insects→ are truly terrestrial

  • first describes when found in old tree stumps in Nova Scotia

Amniotes:

  • synapsids, anapsids and diapsids all appeared in the Carboniferous

→ there is an evolutionary pattern where tetrapods have an early wide diversification

Herbivory:

  • at first, animals ate dead plants/litter

  • in the Carboniferous→ start to find evidence for gnawing on leaves, plants start to produce defences e.g. spines

    → beginning of herbivory and armsrace between animals and plants on the land

Late Carboniferous Climate:

  • 2 continents collided, pushed up a huge mountain range, huge forest across the tropic bury most carbon, are pushed into an ice age- polar ice cap at south pole

  • all biomass is at the equator

    • dominated by lycopsids

    • mountains make it drier and higher→ fern dominated

    • drier and higher→ conifer and seed plant dominated

    • drier and higher→ no plants can live there

    → there were huge coal swaps that got destroyed