W2: L8 = Palaeontology [Terminology] (Prof. Julien)

Question 1

Palaeontology?

Answer 1

= the scientific field that studies fossils.

Question 2

Fossil?

Answer 2

= any trace of life/life activity preserved in rocks.

Question 3

Fossil attributes? (2)

Answer 3

• Does not have to be extinct species only (eg, Homo sapiens).
• Not all extinct species are fossils.

Question 4

Egs of extinct species that are not fossils? (2)

Answer 4

• Frozen mammoths.
• Faeces.

Question 5

Fossil record?

Answer 5

= the record of ancient life & its evolution through geological times.

Question 6

Archaeology?

Answer 6

= the study of ancient cultural products (things manufactured by humans like tools).

Question 7

Eg of life activity?

Answer 7

Footprints.

Question 8

Palaeontology VS Archaeology? (2)

Answer 8

A) Palaeontology
= scientific field that studies fossils.
= since 3.8 Ga.

B) Archaeology
= study of ancient cultural products.
= since 3.3Ma.

Question 9

Fossilisation?

Answer 9

= all processes through which organic matter turns into stone/mineral.

Question 9

Fossilisation attributes? (5)

Answer 9

• Usually, hard tissues only are preserved, because they are already mineralised.
• Usually takes about 1 million years.
• Soft tissues & DNA are rarely preserved (eg, Lystrosaurus preserved with skin).
• Process requires water to cover body parts with sediments (90%).
• As such, most fossils are sea animals & plants.

Question 10

Egs of hard tissue? (3)

Answer 10

• Bark.
• Bone.
• Shell.

Question 11

Fossilisation process steps? (4)

Answer 11

1) Death & decay.
2) Natural burial by water.
3) Diagenesis.
4) Erosion.

Question 12

Natural burial attributes? (2)

Answer 12

• Less than 2 years.
• Brings sediments.

Question 13

Diagenesis attributes? (2)

Answer 13

• Takes at least 1Myr.
• Water slowly flows on.

Question 14

Erosion?

Answer 14

= occurs through water & wind to expose bone.

Question 15

Extinction?

Answer 15

= complete disappearance of a given taxon (species, family, etc).

Question 16

Taxon?

Answer 16

= any classification rank.

Question 17

Taxon attribute?

Answer 17

Classification is arbitrary (made by people for convenience).

Question 18

Classification in Modern species attributes? (2)

Answer 18

• The limit is interbreeding.
• Two individuals are considered the same species if they can breed & produce a fertile offspring.

Question 19

Classification in Fossil species attributes? (2)

Answer 19

• The limit is morphology.
• Two individuals are considered the same species if they look similar (if not, they’re different species), like they would do in modern species (Principle of uniformitarianism).

Question 20

Principle of uniformitarianism?

Answer 20

= if it works today, it might have worked in the past.

Question 21

The fact of extinction attributes? (5)

Answer 21

• That some species go extinct is undeniable.
• Compared biodiversity today vs biodiversity before existence of Homo sapiens (Australia & N. America).
• Extinction is a profoundly palaeontological concept.
• Extinction was defined thanks to palaeontology.
• Before & After Cuvier.

Question 22

Who defined extinction?

Answer 22

Cuvier through studying mammoths.

Question 23

Before Cuvier? (3)

Answer 23

• None believed in complete extinction (eg the Dodo - only extinct in Mauritius).
• No-one cared about the dodo’s extinction.
• Dodo’s were only known to have existed through their fossils.

Question 24

Mass extinction 1 (ME 1)?

Answer 24

= a fast, global and non-selective (affects all types of environment) increase in extinction rate (>50% of genera, >10% of families) over a short period of time.

Question 25

Criteria of something being labelled as an extinction? (5)

Answer 25

• Fast (in terms of geological record).
• Global.
• Non-selective.
• > 50% of genera.
• > 10% of families.

Question 26

Why is “Australian megafauna became extinct 50 000 years ago” not a mass extinction? (3)

Answer 26

1) Is fast but,

2) Is not global, as it only happened in Australia.

3) Is selective, as it only happened to megafauna only.

Question 27

What happens during a mass extinction? (4)

Answer 27

1) Extinction phase.

2) Richness recovery phase.

3) Adaptive radiation.

4) After a mass extinction, biodiversity re-increases steeply due to liberated/available ecological niches to occupy (recovery).

Question 28

Although Prof. Julien gave you the previous mass extinction definition, this one is important to know, what is it [ME 2]?

Answer 28

= Defined based on the fossil record of hard-shelled marine invertebrates & protozoans (fossilisation bias) & is not based on species loss, but on genera & families instead (arbitrariness of taxonomy).

Question 29

Name the Big 5 Mass Extinctions (oldest to current)?

Answer 29

• End Ordovician.
• End Devonian.
• End Permian.
• End Triassic.
• End Cretaceous.

Question 30

ME 2 attributes? (3)

Answer 30

• The dinosaur extinction is not defined on the number of dinosaurs that went extinct.
• Dinosaur fossils are not taken into account to determine tha went extinct during a mass extinction event.
• Stated otherwise, the K-Pg extinction is not considered a mass extinction because dinosaurs went extinct.

Question 31

Two biases to consider when determining mass extinction, i.e., whether the Big 5 MEs were actually MEs?

Answer 31

• Fossilisation bias.
• Taxonomy-Arbitrariness bias.