2.3 Zone Fossils

Question 1

What is a zone fossil?

Answer 1

A fossil that will allow you to relatively date a sequence of rocks

Question 2

What is a good zone fossil?

Answer 2

1. Abundant
2. Widespread
3. Hard parts/easily preserved
4. Easily Recognisable
5. Evolve rapidly
6. Facies independent - a rock forming environment and found in lots of different rocks

Question 3

What are graptolites?

Answer 3

Extinct group of creatures found fossilised in dark shales
Appear like fret saw blades
Each fossil is exoskeleton of a colony of animals whose bodies were housed in tiny cup like thecae arranged in rows along stipes

Question 4

What are thecae?

Answer 4

Tiny cup like or tubular containing coral polyps

Question 5

What are stipe?

Answer 5

A stem or stalk

Question 6

What is pendant?

Answer 6

Old part of lower Ordovician period

Question 7

What is scandent?

Answer 7

Younger part of the upper Ordovician or Silurian period

Question 8

What are goniatites?

Answer 8

Fossils from the Carboniferous period

Question 9

What are ceratites?

Answer 9

Fossils from the Triassic period

Question 10

What are ammonites?

Answer 10

Fossils from the Jurassic period

Question 11

What is a suture line?

Answer 11

The division between the free cheek and the fixed cheek on the trilobite
A simple suture line is older
A frilly and complex suture line is younger