Terrestrilisation Flashcards
What is the period covered by terrestrialisation?
Ordovician to Devonian
What is terrestrialisation?
Colonisation of the land habitat from the sea, via freshwater habitats, by plants and animals
What was the rate of terrestrialisation like?
Staggered/ stepwise changes in multiple lineages these subjected to increased competition over time driving evolutionary change
What are the physiological barriers to life on land?
Methods of respiration
Water management
Osmoregulation
Digestion
Temperature control
Reproduction
Dispersal
Sensory perception -
Support
Locomotion
Why was the method of respiration a barrier to life on land?
Needed to adapt to breathing in atmosphere
Why was water management a barrier to life on land?
Needed for drinking and survival
Why was osmoregulation a barrier to life on land?
needed to maintain water pressure and water retention
Why was digestion a barrier to life on land?
Adapting to eating in the atmosphere
Why was temperature control a barrier to life on land?
water regulates temp while self regulation needed on land
Why was dispersal a barrier to life on land?
Needed movement from birth to living site otherwise clumping occurs
What are the 4 basic methods of water management in the fossil record?
Aquatic
Cryptic
Poikilohydric
Homoiohydric
What are aquatic organisms water management system?
microscopic organisms which live in interstitial water in soils
What are some examples of aquatic organisms that live in interstitial water?
Some microscopic nematodes
Protozoans
some algae
What habitat do cryptic forms live in?
constant high humidity such as soil and tropical forest litter
What are some examples of cryptic form organisms?
Some algae
Homosporous ferns
Earthworms, leeches
What do Poikilohydric organisms require?
high humidity to function but can tolerate desiccation by drying out and rehydrating
when conditions become more favourable
What are some examples of Poikilohydric organisms?
Cyanobacteria
Some bryophytes (mosses, lichens), algae
Some higher plants
Mites
How do Homoiohydric organisms manage water?
osmoregulation, waterproof cuticles,
and internal water transport systems
What are some examples of Homoiohydric organisms?
Most tracheophytes (vascular plants)
Tetrapods (vertebrates, 4 feet)
Insects
Arachnids
Some isopods
Terrestrial molluscs (e.g. gastropods)
How does the cuticle help with water management in homoiohydric organisms?
Waxy external and internal layers to regulate water content
What is the role of stomata in vascular plants?
Stomata within cuticle to regulate water loss, and allow gaseous exchange
What is the role of the xylem?
water transport
What is the role of the phylum?
nutrient transport
What provides the upright support for terrestrial plants?
Cortex
Vascular tissues (xylem, including
wood, and phloem)
lesser extent the cuticle
Roots
What is the purpose of roots?
Tether to land
Penetration into substrate
Key to nutrient and water uptake
Large surface area for weathering reactions
What does the rock record located in Oman depicting the upper Ordovician have potential evidence of?
Spores showing potential terrestrial plant life
Based on research by Charlie Wellman what colonised land first?
Cyanobacteria and algae colonised land first, but restricted to moist environments
what was the main group of organisms involved in terrestrialisation?
Carnivores
When did a multi tiered ecosystem develop?
Upper Ordovician into Silurian
What is the suggested earliest example of a terrestrial animal and its complicated context?
Arthropod track (millipede like) hard to date as in aeolian bed with no other biostratigraphy and potential to just be organism dying
What is Tiktaalik evidence of?
Limbs first starting to developing with Acanthostega being the first to have bones/toes
Where can you find the Devonian Rhynie Chert?
Middle Devonian
Aberdeenshire
What is the importance of the Rhynie chert?
Produces 3d fossils due to being a hot spring and hydrothermal vent area high in minerals like silica
What are Rhyniophytes?
Oldest known land plants, assumed
ancestral to all other land plants lower Silurian to Lower Devonian
What are some of the genera of rhyniophytes?
Cooksonia, Uskiella, Horneophyton
What are Zosterophylls?
Lower to middle Devonian plant adapted to ephemeral environment
example is Zosterophyllum
What are lycophytes?
Lower devonian to present plant which needs water to reproduce
What are sphenophytes?
Mid devonian to recent which need swampy conditions for reproduction
What are trimerophytes and Cladoxyls?
Lower to mid devonian plant adapted to ephemeral environment
Cladoxyls same but late to mid devonian
What are Progymnosperms?
Mid to late Devonian
Adapted for drier environments.
First ‘modern tree
What are Gymnosperms
Seed plants
Late devonian to recent
Dry environments Colonis eupland areas
What did large scale wood production from early trees allow for?
Huge movement of CO2 to the biopshere
What is an example of a model for atmospheric change over geological time?
Berner’s Geocarb (III) model
How has data been collected and generated for Berner’s Geocarb
(III) model?
Weathering uplift factor
Inferred carbon uptake by organisms
Palaeographic model or sea and land area
Gross effect of volcanic weathering, processes
Isotopic composition of fossil seas
Plants to predict metabolic carbon uptake
Land and sea runoff
What is a major drop in co2 in the Palaeozoic associated with?
Terrestrialisation and the colonisation of land by plants
What is the major drop in co2 due to terrestrialisation linked to?
An increase in O2 via transpiration
What is the reason for a major drop of co2 in the Devonian-Carboniferous?
Rise in vascular plants
How did plans affect the sediment when they first established?
Generate decay resistant organic matter
Accelerated weathering by roots
What was colonisation like in the lower Devonian?
Wet settings,
Rivers, lakes, lagoons etc.,
Low diversity,
Low height,
Low density
What was colonisation like in the upper Devonian?
Wet settings plus initial colonisation of uplands,
Increased plant height,
Increased plant density,
Soils developing
What occurred with pedogenesis intensification in the Devonian?
Large increase in thickness and distribution of soils
What was the result of enhanced chemical weathering of soils?
Large scale run off into river systems carrying nutrients into seas and leading to eutrophication and algal blooms causing anoxia
What rock is produced a s a result of bottom water anoxia?
black shale
What 2 anoxia mass extinctions occurred late Devonian?
Kellwasser
Hangenberg
What shift occurred in river systems due to colonisation of plants?
From braided straight channels to meandering rivers
