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A representation of a footprint made by an Apatosaurus that was found in England. Each footprint of the dinosaur measures about 1 metre. The sets of prints indicate that these animals sometimes wandered around in herds. The three-toed footprint possibly belonged to a meat-eating dinosaur that hunted the Apatosaurus.

  • Usually only the hardest parts of an animal become fossilised. The softer parts of the body decay, but may leave imprints in the rock. Plant fossils usually take the form of leaf imprints or petrified tree trunks. Fossils of microscopic grains of pollen have also been found.
  • Fossils therefore are links with the past. But fossilisation is a unique process that only occurs under particular circumstances. Millions of years ago in South Africa, the conditions in the Karoo were very favourable for fossilisation.
  • At that time, the Karoo was a large marshy depression that comprised about three-quarters of the present South Africa. Rivers flowed from the mountains to the depression. Plant fossils provide proof of forests and trees along the riverbeds. The rivers teemed with fish, reptiles and large amphibians, but no signs of birds or mammals have been found. About 190 million years ago tremendous volcanic eruptions occurred in the Karoo because Gondwanaland had started to break up to form the continents that we know today. Large areas were covered in lava and animals were driven away.
  • This means that thousands of well-preserved fossils were conserved in the Karoo.

PALAEONTOLOGISTS

  • People who study fossils are known as palaeontologists. Palaeethnologists study prehistoric people, while palaeobotanists study plant fossils and palaeozoologists study the remains of animals. When all the information obtained in this way is combined, scientists are able to determine what the prehistoric environment was like.
  • There are very few fossils that have human appearance because people probably lived in areas where fossilisation did not take place easily. Humanoid fossils usually are remains of the prey caught by carnivores. There also seems to be fewer humanoid fossils dating from the time after people learnt to use fire. It is possible that fire enabled people to scare carnivores out of caves.

ASSIGNMENT 7

Read the above attentively before answering the following questions. Use a dictionary as source, if necessary.

1. How long is a century?

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2. Why has the Karoo provided so many well-preserved fossils?

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3. Why do we hardly ever find complete fossilised skeletons?

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4. Is the following statement TRUE or FALSE? Motivate your answer.

FOSSILS CAN BE SEEN AS PROOF OF EARLY LIFE.

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(2)

5. Using your own words, give an abbreviated definition of a fossil.

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6. Why would you regard shells as the most common fossils?

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7. Why do the teeth of prehistoric people sometimes provide the best fossils?

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8. Explain what a scientist is, by means of a brief definition of the word.

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9. What is the meaning of the prefix “palaeo-“, as used in the following words: palaeethnologists, palaeobotanist and palaeozoologist?

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TOTAL: 10

Assessment

Learning Outcome 1: The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

Assessment Standard 1.2: We know this when the learner conducts investigations and collects data.

Learning Outcome 2: The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

Assessment Standard 2.3: We know this when the learner categorises information.

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Source:  OpenStax, Natural sciences grade 6. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11079/1.1
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