3.2 Fossils and the Evolution of Life Further Questions and Answers

3.2 Fossils and the evolution of life – Further questions and answers

Q1.

Bk Ch3 S3.2 FQ1

A newspaper report claims that dinosaur fossils have been found in the red bed rock of a Sydney railway cutting. Write a letter to the editor explaining why this could not be true.

A1.

Bk Ch3 S3.2 FA1

Example:

Dear Editor,

The discovery of a dinosaur find in the red bed rock of a Sydney railway cutting, reported recently in your newspaper, cannot be true. Dinosaurs did not roam the Earth until thousands of millions of years after the red bed rock was formed. That rock acquired its red colour when the atmospheric conditions on Earth were very different from the present day. The atmosphere at that time was depleted of oxygen, and aerobic organisms had not yet evolved. Oxygen did not begin to build up in the atmosphere until all exposed rock surfaces containing oxidisable materials were saturated in oxygen. It was only after this change from an anoxic to an oxic atmosphere that conditions became suitable for the evolution of the great diversity of aerobic life-forms that included the dinosaurs.

Yours sincerely,

A. Dinah Shaw

Q2.

Bk Ch3 S3.2 Q2

aExplain why igneous rock does not contain fossils.

bHow is igneous rock important to the interpretation of the fossil record?

A2.

Bk Ch3 S3.2 A2

aIgneous rocks are formed by volcanic activity. Hot lava would destroy any life-forms in its path, so no fossils can be preserved in this kind of rock.

bIgneous rock is important in dating the age of fossils because it provides a reference point for fossil-bearing rock layers above and beneath it. For example, if a layer of sedimentary rock lies directly beneath a layer of igneous rock that has been dated at 200 million years old, then this indicates the relative age of the fossils in the sedimentary layer to be at least 200 million years old.

Q3.

Bk Ch3 S3.2 FQ3

Investigate some of the different theories that have been suggested to account for the extinction of the dinosaurs. Display your findings in a way suitable for giving a class presentation; for example, overhead transparencies, a computer display, such as PowerPoint, or a poster.

A3.

Bk Ch3 S3.2 FA3

Theories include meteor strike and change in climatic conditions. Discussion should include a description of the event and an explanation of how the event affected the global ecosystem as well as dinosaurs specifically. For example, a cataclysmic meteor strike would have sent up a dust cloud that engulfed the entire Earth, blocking out sunlight thereby causing a significant decrease in global temperature; such a dust cloud would also block sunlight for photosynthetic plants causing a chain reaction of starvation for animals along food chains.

Q4.

Bk Ch3 S3.2 FQ4

Research the ideas about the origins of life from an ancient culture.

Present these as pictures or a story for children.

A4.

Bk Ch3 S3.2 FA4

As for question 3, the work presented will depend on the choice of culture and the method of presentation.

3.2 Fossils and evolution FQApage 1 of 2