Dubiofossil
Encyclopedia
The term dubiofossil is a portmanteau word
used in geology and paleontology for a problematic structure that looks like a fossil, but whose biologic origin is uncertain. (From Latin dubius, + fossil). It has been mainly used for remains found in rocks dating from the early history of the Earth (Precambrian rocks), but is also applicable in other settings such as problematic microbe-like forms in meteorites.
Although ultimately such structures are either biogenic (i.e., fossil
) or abiogenic (i.e., pseudofossil
), the information available at the time of study is insufficient to make an unambiguous determination. They belong to the dubiofossil category temporarily, awaiting additional evidence that will allow them to be removed from this category and attributed to the fossils or the pseudofossils. For example, see ALH84001
.
Physical and chemical processes can produce structures that look indistinguishable from some that are formed by biologic activity, presenting a hurdle in their interpretation.
Living systems are capable of metabolism, reproduction, mutation, and propagation of the mutations. Lines of evidence for biogenicity, called biosignature
s, come in various forms and appear at various scales, ranging from the atomic to the planetary dimension.
Molecule-building, cell division, colony formation, respiration, excretion, active motility are amongst the biologic processes that effect changes in the environment and can leave distinctive morphologic features or signature chemical by-products in the geologic record.
These attributes are susceptible to be modified or obliterated over geologic time, making it more difficult to recognize them in the rocks. The case for biogenicity is most robust when multiple lines of evidence converge.
Portmanteau word
A portmanteau or portmanteau word is a blend of two words or morphemes into one new word. A portmanteau word typically combines both sounds and meanings, as in smog, coined by blending smoke and fog. More generally, it may refer to any term or phrase that combines two or more meanings...
used in geology and paleontology for a problematic structure that looks like a fossil, but whose biologic origin is uncertain. (From Latin dubius, + fossil). It has been mainly used for remains found in rocks dating from the early history of the Earth (Precambrian rocks), but is also applicable in other settings such as problematic microbe-like forms in meteorites.
Although ultimately such structures are either biogenic (i.e., fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
) or abiogenic (i.e., pseudofossil
Pseudofossil
Pseudofossils are inorganic objects, markings, or impressions that might be mistaken for fossils. Pseudofossils may be misleading, as some types of mineral deposits can mimic lifeforms by forming what appear to be highly detailed or organized structures. One common example is when manganese oxides...
), the information available at the time of study is insufficient to make an unambiguous determination. They belong to the dubiofossil category temporarily, awaiting additional evidence that will allow them to be removed from this category and attributed to the fossils or the pseudofossils. For example, see ALH84001
ALH84001
Allan Hills 84001 is a meteorite that was found in Allan Hills, Antarctica on December 27, 1984 by a team of U.S. meteorite hunters from the ANSMET project. Like other members of the group of SNCs , ALH 84001 is thought to be from Mars. However, it does not fit into any of the previously...
.
Physical and chemical processes can produce structures that look indistinguishable from some that are formed by biologic activity, presenting a hurdle in their interpretation.
Living systems are capable of metabolism, reproduction, mutation, and propagation of the mutations. Lines of evidence for biogenicity, called biosignature
Biosignature
A biosignature is any substance -such as an element, isotope, or molecule - or phenomenon that provides scientific evidence of past or present life. Measurable attributes of life include its complex physical and chemical structures and also its utilization of free energy and the production of...
s, come in various forms and appear at various scales, ranging from the atomic to the planetary dimension.
Molecule-building, cell division, colony formation, respiration, excretion, active motility are amongst the biologic processes that effect changes in the environment and can leave distinctive morphologic features or signature chemical by-products in the geologic record.
These attributes are susceptible to be modified or obliterated over geologic time, making it more difficult to recognize them in the rocks. The case for biogenicity is most robust when multiple lines of evidence converge.