The work of Palaeontologists

Over the last 150 years or so, a special science has developed to study fossil animals and plants. It is called palaeontology, which means the study of ancient life.

Palaeontologists try to reconstruct the animals and plants of the past, and find out what they looked like and how and where they lived. The palaeontologist's work requires many up-to-date scientific techniques, most of which are carried out in modern laboratories. First the palaeontologist has to find fossils, and to do this he or she needs to know a great deal about rocks and rock formations.

The geological time-scale

In general, the deeper a layer of rock, the older it is, assuming that the Earth's crust has not moved. Geologists have investigated the order of the rock layers, and the fossils they contain. They have given names to groups of rocks which seem to be related by their nature and the fossils they contain. In this way, the 'geological time-scale' was drawn up, on which the relative ages of various rocks and the different phases of mountain-building can be shown.

At first it was impossible to put dates to this calendar, and only the order was known. However, it was discovered that certain rocks contain radioactive materials, such as carbon, which break down slowly and steadily at a known rate. By measuring the amount of radio-active material in a rock, a palaeontologist can work out its age with some accuracy. If the rock contains fossils, he or she then knows how long ago each animal or plant lived.

Careful recording is necessary

When the palaeontologist has found a fossil in, say, the exposed face of a cliff or quarry, he or she cannot just pop it into a bag. First the palaeontologist has to record exactly where the fossil was found and in which rock layer it occured.

If there are a number of separate bones or pieces to the fossil, it is important to record their exact positions. For example, all the bones of the backbone will have to be numbered and photographed in their proper sequence, otherwise no one will know in what order they should be placed when the skeleton is being put together again.

Dealing with large fossils

The parts of a large fossil will probably be treated to stop them from cracking or crumbling before they can be removed. It may take many months of delicate and skilled work before a fossil skeleton can be mounted for exhibition and examination. If you find a large or unusual fossil it is, therefore, best to ask an expert from the local museum to deal with it.

Click on the image to see the geological timescale
enlarged.

Clues from fossils

The palaeontologist tries to compare a new fossil skeleton with the skeletons of modern animals. From the size and distribution of various muscle attachments in the extinct animal, palaeontologists can gain an idea of the size and shape of the extinct animal, and may learn whether it walked on its hind legs or on all fours, and therefore if it could burrow, fly, swim or climb trees.

There may be evidence on the fossil as to whether the animal was scaly, feathery, or furry but there is rarely any clue as to its colour.

A fossil dragonfly