Chapter 8 - The fossil record

Question 1

What are examples of environmental changes?

Answer 1

The continental drift and bush fired

Question 2

What is the geological time scale?

Answer 2

Physical changes & the changes to living things forming the history of the earth displayed on a map

Question 3

How old is the earth?

Answer 3

4.56 billion years

Question 4

What is the geological time scale broken down into?

Answer 4

Eons (largest length of subdivision)
Eras
Periods
Epochs

Question 5

What is a fossil?

Answer 5

preserved remains or impression of an organism that is no longer extant (alive)

Question 6

What are trace fossils?

Answer 6

• A preserved impression of an organism
• Takes form in footprints, burrows, or coprolites (fossilised faeces).

Question 7

What are body fossils?

Answer 7

• Formed from an actual organism
• An organism, or a part of it, is turned into a rock
• A mold fossil is formed when the organism decomposes

Question 8

What is the process of fossilisation?

Answer 8

• Organism dies
• Soft tissues decay and remains are buried
• Sediment builds above and adds pressure
• Dissolved minerals react with hard remains & replaces the organic matter with hard minerals
• The solidified sediment above the fossils erode
• Discovery of fossil

Question 9

What are the conditions needed for fossilisation?

Answer 9

• Harder remains
• Fast covering of remains
• More likely to form in water than on land

Question 10

What do dating fossils do?

Answer 10

Shows how organisms evolve over time

Question 11

What rocks are fossils found in?

Answer 11

Sedimentary rock, and it forms layers called strata

Question 12

What is relative dating?

Answer 12

Fossils found in lower strata are older than the fossils found in upper strata

Question 13

What is absolute dating?

Answer 13

Estimating the age of rocks, and one way is radiometric dating.

Question 14

What is radiometric dating?

Answer 14

measuring the percentage of radioactive isotopes in a substabnce. Radioactive isotopes decay to a stable atoms at a known rate called half-life. Half-life is the time it takes for half the radioactive atoms in the substance to decay.

The longer the half-life = suitable for dating older fossils

Question 15

What is evolution?

Answer 15

It is the change in heritable characters of a population or species over time.
Presence of fossils is evidence of the existence of extinct organisms.

Question 16

What are transitional fossils?

Answer 16

Shows evidence of organisms that shared characteristics with both ancestral (ancient) form and descendant (modern) form.
When placed in chronological order, it can show the evolutionary history of a species