7. Ediacaran biota

Question 1

Ediacaran biota are the first example of what?

Answer 1

Multicellular life on earth

Question 2

From when did cells with nuclei exist on Earth?

Answer 2

1200Ma

Question 3

Approximately how many years ago did Ediacaran biota first appear?

Answer 3

575/80Ma

Question 4

How many years after Earth’s formation did Ediacaran biota appear?

Answer 4

4 Billion

Question 5

Were Ediacaran biota hard or soft bodied?

Answer 5

Soft (suggested to be)

Question 6

Were Ediacaran biota marine or land life?

Answer 6

Presumed marine

Question 7

Were Ediacaran biota part of the Cambrian explosion?

Answer 7

No, they appeared just before it and are thought to have gone extinct just before it

Question 8

Were Ediacaran Biota animals?

Answer 8

They are not universally accepted to be, suspected to possibly be fungi/molluscs/lichens etc

Question 9

What is a possible deduction if Ediacaran Biota are fully extinct?

Answer 9

They may have been a failed life experiment from which nothing further evolved from

Question 10

Approximately how many species of Ediacaran Biota have been described so far?

Answer 10

200

Question 11

Name the 3 distinct fossil groups of Ediacaran Biota oldest to youngest.

Answer 11

Avalon Biota
White Sea Biota
Nama Assemblage

Question 12

What time period did the Avalon Biota span?

Answer 12

580-575 Ma

Question 13

What time period did the White Sea Biota span?

Answer 13

560-555 Ma

Question 14

What time period did the Nama Assemblage span?

Answer 14

550-542 Ma

Question 15

Until the 1950s, the Precambrian was thought to be devoid of what?

Answer 15

Fossils

Question 16

What is ‘Charnia’?

Answer 16

A fossil found in Charnwood forest that was the first definite Precambrian macrofossil

Question 17

What are 3 possible reasons for the emergence of Ediacaran Biota?

Answer 17

• 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

Question 18

‘____________’ mats of ‘____________ ‘ were incredibly important in the Ediacaran system

Answer 18

Microbial mats of microorganisms

Question 19

What is one possible reason why Ediacaran biota are hard to place in the tree of life?

Answer 19

Possibly evolved from several ancestors, with different species relating to different ancestors

Question 20

What type of life defines the Avalon biota?

Answer 20

Deep water filter feeders

Question 21

What defines the White Sea biota?

Answer 21

A major peak in diversity followed by a mass extinction before the Nama assemblage

Question 22

What defines the Nama assemblage?

Answer 22

Creatures thought to have lived mostly in microbial mats, very worm abundant.

Question 23

What are 3 explanations for the dynamic between Ediacaran Biota and Cambrian life?

Answer 23

1. Sudden extinction (catastrophe)
2. Two stage extinction (pulsed catastrophe)
3. Simple replacement of a biota at the expense of another (Ediacaran biota lose an ecological battle)

Question 24

What reason is there that the last Ediacaran assemblage may have actually been the first stage of the Cambrian explosion?

Answer 24

Most Ediacaran died out 9mil years earlier,

Question 25

What are some theories for the extinction of Ediacaran Biota?

Answer 25

• 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

Question 26

What are some examples of animal attributes that Ediacaran biota are surprisingly the first example of?

Answer 26

Predatory nature, bifurcation, skeletons

Question 27

Some recent studies suggest an extinction event is to blame for lower diversity in the Nama assemblage as opposed to what?

Answer 27

Worse fossil preservation / abundance

Question 28

The extinction levels experienced in the Nama Assemblage are comparable to what?

Answer 28

The big 5 Phanerozoic extinctions