Subfossil

A subfossil dodo skeleton

Subfossil refers to any remains of a once living organism in which the fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization. Such unfossilized or partially fossilized remains may include bones, exoskeletons, nests, skin imprints, or fecal deposits. Subfossils are often found in caves or other shelters where they can be preserved for thousands of years.

The main importance of subfossil versus fully fossilized remains is that the former contain organic material, which can be used for radiocarbon dating or extraction and sequencing of DNA, protein, or other biomolecules. Additionally, isotope ratios can provide information about the ecological conditions under which extinct animals lived. Subfossils are useful for studying the evolutionary history of an environment and can be important to studies in paleoclimatology.

Subfossils are often found in depositionary environments, such as lake sediments, oceanic sediments, and soils. Once deposited, physical and chemical weathering can alter the state of preservation. Small subfossils can be ingested by living organisms.

Subfossil remains that date from the Mesozoic are exceptionally rare, usually in an advanced state of decay and consequently much disputed. The vast bulk of the material comes from Quaternary sediments, including many subfossilized chironomid head capsules, ostracod carapaces, diatoms, and foraminifera.