Preparing fossils, reconstructing the past

Preparing fossils

Palaeontologists use different techniques to remove fossils from rocks depending on the properties of the rock and the composition of the fossils themselves. Some rocks like mudstone or sandstone are soft so it is quite easy to remove the fossils using simple hand tools. Other rocks, such as limestone, are more difficult to excavate. In those cases chemical methods using acids might be used to remove some of the rock.

Once fossil bones are extracted from the rock matrix they are treated with special glues to preserve them and protect them from damage.

Telling the difference between a rock and a fossil

A fossil bone may now be ‘rock’ (mineralised), but it still has some similarities to modern bone. Bone has tiny lines on the surface, a dense outer layer, and an inner spongy structure that resembles honeycomb. These can still be seen in fossil bone but not in rock.

How do we complete the picture?

Once the fossils are prepared and preserved, palaeontologists will study the remains in order to determine what type of dinosaur they belonged to and even what it looked like and how it lived.

Determining species

Identifying the type or species of dinosaur recovered (or if it even is a dinosaur), is the main priority of palaeontologists. The first step is to compare the remains to other more complete examples to see if they match any known species. If they do, then those examples can be used to help reconstruct the new find. If they don’t, then it is possible that a new species has been discovered.

Reconstructing lifestyle

Scientists study the new remains to determine relationships to other known species and genera. Comparisons are made with these and also with living animals in order to reconstruct the skeleton and lifestyle of the dinosaur. Aspects of its life such as size, movement, weight and shape can also be determined. These are relatively easy, but other aspects such as growth rates and behaviour are more speculative.

Once fossils are prepared and preserved, the bones are assembled and a detailed drawing or reconstruction is made of the skeleton. Knowledge of dinosaur and animal anatomy helps rebuild the body with muscles, tendons and skin and so recreate a 'living' dinosaur.

How do we work out the external appearance of dinosaurs?

Palaeontologists rely on artistic interpretation to reconstruct dinosaur appearance and behaviour. As a result, artists have taken an unusually central role in the scientific process of reconstructing dinosaurs.

The skins of some living animals and rare dinosaur fossil skin impressions give us some idea about the skin surface of dinosaurs. However, the colours or patterns of reconstructions are educated guesswork based on living animals with similar lifestyles and habitats. Since it is likely that dinosaurs saw in colour like modern birds and reptiles, skin colour was probably an important feature.

Digital reconstruction of dinosaurs

The growth of technology has introduced the digital age of dinosaur reconstruction. Computer programs blend cutting-edge wizardry with traditional techniques of drawing and sculpture to bring new realism to dinosaur movement and behaviour. These can also incorporate dinosaur movement that static art can not (think of the BBCs ‘Walking with Dinosaurs’ or the movie ‘Jurassic Park’).