Shining a light on the depths of time

Palaeontology (from the Greek palaeo meaning "old", ontos meaning "being", and logos meaning "discourse") is literally the "science of ancient life". This scientific discipline studies extinct organisms found in the form of fossils within sedimentary terrains.

Fossils are the remains of animals or vegetation that lived in the past. These may be teeth, bones, shells, seeds and leaves but also footprints, nests, eggs, etc. Dating back more than three billion years, the oldest fossils are stromatolites, forms of bacterial life that occur in static colonies.

Fossilisation is a rare and erratic phenomenon. The burial of an organism by sediments must occur very rapidly after the organism dies. Then the process of mineralisation begins, during which the formerly living tissues are replaced by mineral substances. In exceptional circumstances, in muds that are lacking oxygen for example, soft tissues can be preserved.

While the fossil record is a distorted and incomplete sample of extinct flora and fauna, it does allow us to understand past biodiversity. Fossils also allow us to reconstruct the way of life (locomotion, diet) of extinct animals as well as their geographical and chronological distributions. Finally, they help us understand the evolution of species over geological timespans.

Today, observation and investigation techniques benefit from an approach that is both specialised and multi-disciplinary. Palaeontology is now joined by palaeoecology, palaeoclimatology, palaeohistology (the study of thin slices of bone to examine its internal composition), scanning imagery that reveals hidden structures (such as the inner ear), and of course DNA research on more recent specimens. The past has never belonged so much to the future!