Interpreting Past Environments

Question 1

What do we need to interpret fossils?

Answer 1

A temporal framework

Question 2

How is a temporal framework done?

Answer 2

Use radiometric methods to date rocks

Date fossils against the rocks which can then be put into the framework

Question 3

What is continental configuration? How is this done?

Answer 3

Reconstructing the continents to see how they looked in the past - spatial framework

Look at rocks and look for remnant magnetism and this helps know where continents were

Question 4

How can past environments be interpreted?

Answer 4

1) Nature of sediments - relate this to present day distribution

2) Nature of fossil content - relate to present day distribution

3) Distribution of climatically sensitive sediments and fossils

4) Environmentally discriminating isotopes

5) Environmentally influenced characteristics of organisms e.g. tree rings and some organisms have different shapes based on salinity

Question 5

What type of world did dinosaurs live and evolve in?

Answer 5

Warm greenhouse world

Had high sea levels

High CO2 levels

Lower O2 levels

Question 6

Give some examples of how environmentally discriminating isotopes can be used to interpret past environments

Answer 6

Rubisco prefers carbon 12 over 13

Boron can be used to work out atmospheric CO2

Forams are important as they discriminate against certain isotopes

Question 7

How does modelling work when interpreting past environments?

Answer 7

Apply physics of climate systems today on the past

Get more unsure further back in time you go

Can then test models against fossils and rocks

Question 8

What were conditions like around the poles during late Jurassic and Early Cretaceous?

Answer 8

Had land masses at and around the poles - no ice caps

Think they had polar winters and summers like today as Earth rotation is similar - so 24hr light/dark cycles

Cool temperate envrionment - even cooler in winter (know this due to ice heave and polygon structures associated with bones)