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.