Rise of the Animals

Question 1

The Cambrian Explosion

Answer 1

• 541-520Mya
• most animal forms you would expect to fossilise appear in the fossil record

Question 2

Lagerstätten

Answer 2

Sedimentary deposits with extraordinary fossil perseveration

Question 3

Why doesn’t burrowing fit into the Cambrian Explosion theory?

Answer 3

• implies front and back, with internal organisation (like modern bilaterian worm)
• Yilingia

Question 4

Clade

Answer 4

Evolutionary groups

Question 5

Grade

Answer 5

Level of organisation

Question 6

Fossils provide

Answer 6

Windows

Question 7

Explosive

Answer 7

Origination of complex life forms

Question 8

Free calcium deposition in skeleton results in

Answer 8

Ecological arms race based on skeletal predation

Question 9

It’s difficult to classify Ediacaran animals in the

Answer 9

Modern taxa

Question 10

The Cambrian explosion was a

Answer 10

Relatively short period in geological and evolutionary time

Question 11

Burrows appear as

Answer 11

Fossilised sediment traces

Question 12

The molecular clock

Answer 12

Contradicts paleontological data

Question 13

What are the ‘internal’ theories of the Cambrian explosion

Answer 13

Some genetic innovation(s) gave animals previously lacking ability to evolve these body plans

Question 14

What are the ‘external’ theories of the Cambrian explosion?

Answer 14

Some planetary change like gas concentrations, calcium availability etc provided an external push

Question 15

What are the ‘ecological’ theories of the Cambrian explosion

Answer 15

Competition and predation shifts

Question 16

The Cambrian explosion as an artefact

Answer 16

Of a patchy fossil record, small, soft ancestors never been fossilised and overinterpretation of persisting data

Question 17

Ediacaran fossils generally lack

Answer 17

Bilateral symmetry

Question 18

Kimberella is proposed by some to be an

Answer 18

Early mollusc (would near bilateral symmetry)