Fossils: Window to the past

Drying & Desiccation

What is desiccation?

Desiccation, also known as mummification, is a very unique and rare form of fossilization. Desiccated/mummified fossils are next in quality to frozen fossils. Bones and tissues of desiccated organisms of the desert are well preserved, although they often fall apart at the slightest touch. With desiccated fossils, even the skin and hair retain their original color. For example, a fossil mummy of Anatosaurus was air-dried before natural burial. When fossilized, there were impressions of the skin in the hardened burial matrix leaving a detailed surface pattern. These extremely fragile fossils are so rare that a collector who finds one is likely to turn it over to a museum. Such fossils are the only accurate evidence available to the scientist trying to restore a bag of bones and give it the proper clothing.

Conditions leading to desiccation

Desiccation takes place when organic material is found in conditions void of moisture. This results in dehydration and the material can then be preserved for thousands of years. Arid regions are favorable environments for desiccation. Dry caves also prove excellent conditions. About the time that the mammoths were freezing in the northlands, other vertebrates crawled into caves in the southern desert region and died. In this aseptic environment, dead organic material becomes mummified. Not surprisingly, a few of the Ice-Age animals did just that. Extinct ground sloths have been found lying on or near the surface. The cave-dwelling sloth was also represented by their dried dung.