7. Ediacaran biota Flashcards
Ediacaran biota are the first example of what?
Multicellular life on earth
From when did cells with nuclei exist on Earth?
1200Ma
Approximately how many years ago did Ediacaran biota first appear?
575/80Ma
How many years after Earth’s formation did Ediacaran biota appear?
4 Billion
Were Ediacaran biota hard or soft bodied?
Soft (suggested to be)
Were Ediacaran biota marine or land life?
Presumed marine
Were Ediacaran biota part of the Cambrian explosion?
No, they appeared just before it and are thought to have gone extinct just before it
Were Ediacaran Biota animals?
They are not universally accepted to be, suspected to possibly be fungi/molluscs/lichens etc
What is a possible deduction if Ediacaran Biota are fully extinct?
They may have been a failed life experiment from which nothing further evolved from
Approximately how many species of Ediacaran Biota have been described so far?
200
Name the 3 distinct fossil groups of Ediacaran Biota oldest to youngest.
Avalon Biota
White Sea Biota
Nama Assemblage
What time period did the Avalon Biota span?
580-575 Ma
What time period did the White Sea Biota span?
560-555 Ma
What time period did the Nama Assemblage span?
550-542 Ma
Until the 1950s, the Precambrian was thought to be devoid of what?
Fossils
What is ‘Charnia’?
A fossil found in Charnwood forest that was the first definite Precambrian macrofossil
What are 3 possible reasons for the emergence of Ediacaran Biota?
- Increase in oceanic nutrients post Snowball Earth
- Increase in oxygen in oceans, especially deep oceans
- Drifting of supercontinent Rodinia created more shallow-shelf ocean environments
‘____________’ mats of ‘____________ ‘ were incredibly important in the Ediacaran system
Microbial mats of microorganisms
What is one possible reason why Ediacaran biota are hard to place in the tree of life?
Possibly evolved from several ancestors, with different species relating to different ancestors
What type of life defines the Avalon biota?
Deep water filter feeders
What defines the White Sea biota?
A major peak in diversity followed by a mass extinction before the Nama assemblage
What defines the Nama assemblage?
Creatures thought to have lived mostly in microbial mats, very worm abundant.
What are 3 explanations for the dynamic between Ediacaran Biota and Cambrian life?
- Sudden extinction (catastrophe)
- Two stage extinction (pulsed catastrophe)
- Simple replacement of a biota at the expense of another (Ediacaran biota lose an ecological battle)
What reason is there that the last Ediacaran assemblage may have actually been the first stage of the Cambrian explosion?
Most Ediacaran died out 9mil years earlier,
What are some theories for the extinction of Ediacaran Biota?
- Competition from cambrian life
- Eaten by cambrian life or cambrian life grazing on their microbial mat
- Environmental change like alteration of ocean chemistry or temp
- Preservation bias, not actually extinct at accepted time, just poorly preserved
What are some examples of animal attributes that Ediacaran biota are surprisingly the first example of?
Predatory nature, bifurcation, skeletons
Some recent studies suggest an extinction event is to blame for lower diversity in the Nama assemblage as opposed to what?
Worse fossil preservation / abundance
The extinction levels experienced in the Nama Assemblage are comparable to what?
The big 5 Phanerozoic extinctions
