Fossils

Question 1

What is a fossil record?

Answer 1

History of life as documented by fossils, the remains or imprints of the organisms from earlier geological periods preserved in sedimentary rock.

Question 2

Is the fossil record bias?

Answer 2

Yes, but in a predictable way.

Question 3

What is the purpose of fossils (and record)?

Hint: 3 purposes

Answer 3

1. Can provide important information (e.g relative rock dating).
2. Past changes in the environment may be important in predicting and understanding where we are headed.
3. Helps us understand what the implications of the current crash in biodiversity might be.

Question 4

What is a fossil?

Answer 4

A fossil is any trace of an organism that is usually preserved in rocks, including their:

1. Body parts
2. Tracks and trails
3. Chemical signature (scent)
4. Excreta

Question 5

Are all environments capable of preserving fossils well? And where do they typically come from?

Answer 5

No, not all environments are. Fossils dominantly come from marine environments

Therefore, fossil record bias.

Question 6

How is the fossil record bias? (in a predictable way)

Hint: 3

Answer 6

1. Not all environments are capable of preserving fossils. Fossils dominantly come from marine environments
2. Not all organisms are capable of being preserved.
   Fossils are dominantly hard parts (e.g shells, bones).
3. There is a low number of individuals/restricted geographic range reduces the likelihood of preservation.
   Fossils generally represent the most common form.

Question 7

Example of how the fossil record is helpful

Answer 7

Whales have a good fossil record, indicating they had legs once but now no longer.

Or humans were once four-legged and now two-legged (bipedal).

Can show the evolution of species

Question 8

What are three intermediate forms of fossils?

Answer 8

1. Fish (gills, scales, fins)
2. Tetrapod (rib bones, mobile neck with separate pectoral girdle, lungs).
3. Fishapod (half fish + half tetrapod, limbs, bones, joints + functional wrist joint on radiating, fish-like fins instead of toes, half-fish/tetrapod ear region).

Question 9

How do you preserve an organism?

Answer 9

Normally the remains of a plant or animal are destroyed.

Two special conditions are needed o avoid this:

1. Rapid burial
2. the possession of hard parts

Question 10

What are the two special conditions to avoid all the remains of a plant or organism being destroyed?

Answer 10

1. Need to harden (geothermal process)
2. Rapid burial

When an organism perishes, its soft parts are often quickly eaten by scavengers or decomposed by bacteria. Occasionally, the remains are buried by sediment, when this happens the remains are protected from the environment, where destructive processes take place.

Animals plants have a better chance of being preserved if they have hard parts. Although traces of soft-bodied animals (e.g jellyfish, worms, insects exist) but are not common. Hard parts such as shells, bones, teeth are predominant in the record of the past.

Question 11

What gives an organism or plant the best chances of being preserved?

Answer 11

Animals and plants have a better chance of being preserved if they have hard parts such as shells, bones or teeth. Although traces of soft-bodied animals (jellyfish, worms, insects exist) but are not common.

Hard parts including shells, bones and teeth are predominant in the record of the past.

Question 12

If the remains are buried by sediment does it better the chance of the fossils being preserved?

Answer 12

Yes, because they are protected from the environment where destructive processes take place.

Question 13

What are the three options that can happen when the animal or plant dies/decomposes?

Answer 13

1. Disappear
2. Nothing could happen
3. Dissolve = moulds
4. Infill/cast replacement (the rock around it could mould in it/around and replacement and fill happens (common in trees).
5. Insects in amber
6. Mammals in ice (died 15,000 years ago).
7. Carbon film (dark patch around the skeletal bones)
8. Encased in tar

Question 14

What is recrystallisation?

Answer 14

The crystals from the original shell crystalised to other shells around them, resulting in a vague shape (can’t collect very hard).

Question 15

What does internal mean?

Hint: In the sense of fossils

Answer 15

Go in the organism

Question 16

What does external mean?

Hint: In the sense of fossils

Answer 16

Go around the organism (hole in the middle)

Question 17

What can fossils suggest?

Answer 17

They can suggest and show seasonal migrations

E.g Elephants are found/trapped in the La Brea, LA, tar pits suggesting they were migrating.

Can suggest previous homes/environments

E.g Remains of certain clam shells are found in limestone, geologists can assume that the region was once covered by a shallow sea.

Question 18

What do fossils with thick shells suggest?

Answer 18

That they were capable of withstanding pounding waves so, must have inhabited shorelines.

Question 19

What do fossils with thin/delicate shells suggest?

Answer 19

Indicate that they were in deep, calm offshore waters.

Question 20

What can be interpreted of where thick and thin shells were found?

Hint: 2 things

Answer 20

The position of the fossils of thick and thin shells suggest the approximate position of ancient shorelines.

They can also suggest the temperatures of the water by identifying what fossils are found in limestone (e.g coral).