Cambrian explosion

Question 1

What is the Burgess shale famous for?

Answer 1

Exceptional preservation of the soft parts of its fossils

Question 2

Name 3 fossils that were studied

Answer 2

Marella splendens
anomalocaris
microdictyon

Question 3

Describe Ediacaran fauna

Answer 3

Mostly sessile, represent the earliest known complex organisms, radiated in avalon explosion. (mm-m)

Question 4

Give the three types of factors that may have caused the explosion

Answer 4

Environmental
Ecological
Developmental

Question 5

Give examples from each type of factor contributing to why the explosion happened

Answer 5

Evironmental:
1. Increased oxygen levels
2. End of snowball earths
3. Extinction of Ediacaran fauna
4. polar wander and methane burps
Ecological:
1. Origin of predation/ arms race
2. ecological niche saturation
Developmental:
1. origin of bilateral developmental system
2. canalization/developmental lock

Question 6

What is ‘Spriggina’?

Answer 6

fossil from ediacaran, may represent a bilateral with head and two sides. 3-5 cm long. may have had eyes and been predatory.

Question 7

What are lagerstatten?

Answer 7

sedimentary deposit that has fossils with exceptional preservation.

Question 8

How long did the explosion last?

Answer 8

20-25 million years (relatively short event)

Question 9

What was the most common animal in the Burgess shale?

Answer 9

Marella splendens (24-26 body segments, arthropod, 2cm/less, moulted, bottom dwelling scavenger)