The colour of fossils

The colours sported by animals and plants when they were alive are rarely preserved. The colours of fossils are especially governed by the nature of the ground and its geological history: the colour of the sediment surrounding the fossil (gangue), burial temperature, circulation of metal-rich fluids, vegetation and climate.

The colouration of fossils linked to the geological history of the burial zone can be very useful to palaeontologists. The grades of colouration of certain microfossils (conodonts and foraminifera), ranging from light brown to black, can reveal the precise maximum temperature attained by fossils and their gangue.

Cu: Copper gives the fossil a greenish tint.
O₂: The absence of oxygen in the burial environment can result in a black colouration.
: The blue coloration of fossils may be caused by the incorporation of clay minerals.
Fe: In the presence of iron compounds, for example haematite, fossils take on a yellow to red colour. A notable case is cherry marble or ammonitico rosso.
C°: A high temperature may darken the fossil.

Pachycrommium hybridum
Eocene, Bartonian
From - 41 to - 38 Ma

The original colours of fossils

Geochemical analyses and certain types of imagery, most notably using synchroton radiation, have recently revealed the presence of certain pigments in various fossils, particularly in fossil bird feathers.

Pigments