10.4 4.2.5 fossils  (Page 3/4)

The scientist finds some igneous rock which he assumes to be the same age as the sedimentary rock in which the fossil was found.

The scientist measures the ratio of parent to daughter elements in this igneous rock.

The scientist concludes the age of the igneous rock, as previously explained.

The scientist concludes the age of the fossil from the age of the igneous rock.

Link to movie: Fossil dating 6’14”

<iframe width="425" height="349" src="http://www.youtube.com/embed/K5GWSbBkjuk?hl=en&fs=1" frameborder="0" allowfullscreen></iframe>

Caption: This is a 6’14” video in which radiometric dating is explained.

Fossil tourism

South Africa has a number of fossil-rich areas which attract tourists. The Cradle of Mankind (Maropeng, Sterkfontein, Kromdraai and surrounding areas) andLangebaan are examples of places in South Africa which attract fossil tourism.

Maropeng is a Tswana word for the origin of mankind.

Living fossils

Many creatures which disappeared from the fossil record millions of geological years ago have been found to be alive still and almost identical to theirfossilized counterparts.

There are many examples of living fossils. The Tuatara, which looks like a lizard with a beak-shaped head, disappears from the record 135 milliongeological years ago, but is still alive. Lingula, a worm-like creature which disappears from the record about 400 million years ago, not very far from thebeginning of metazoan evolution, is still alive and shows no sign of significant evolution from its fossilized ancestors. This suggests that we maybe interpreting the fossil record incorrectly, and our conclusions based on it may be wrong.

Activity: fossils

1.Name / give the term for:

• Turning to stone
• A fossil in which the surroundings became stone, leaving a cavity where the body had been
• The time period and era, according to the geological column, when dinosaurs first appeared
• The time period and era, according to the geological column, when dinosaurs became extinct
• A person who studies fossils
• A person who studies rocks
• Layers of deposited material
• No members of that organism exist anymore
• The time era, according to the geological column, when mankind evolved

2.For each of the following sentences, say whether the information is: (Circle i / ii / iii)

• Accepted by definition if people have defined this to be so, or
• Known by observation if people have observed this to be so, or
• Deduced if people have come to this knowledge by reasoning.

• During petrifaction, minerals enter, harden, and turn a body to stone.[ i / ii / iii]
• The Triassic Period is more recent than the Permian Period. [ i / ii / iii]
• The oldest fossils are 650 million years old. [ i / ii / iii]
• A film fossil is a carbon mark left on rock e.g. by leaves. [ i / ii / iii]
• The deepest rocks with reptile fossils are classed as Carboniforous. [ i / ii / iii]
• Reptiles first evolved 350 million years ago, at the start of the Carboniforous period. [ i / ii / iii]
• Only 2/3 of all types of organisms which have ever lived have left any fossils.[ i / ii / iii]