Taphonomy

The term taphonomy (from Greek táphos, τάφος 'burial' and nomos, νόμος 'law') was introduced to paleontology in 1940[1] by Soviet scientist Ivan Efremov to describe the study of the transition of remains, parts, or products of organisms from the biosphere to the lithosphere.

[2][3] The term taphomorph is used to describe fossil structures that represent poorly-preserved, deteriorated remains of a mixture of taxonomic groups, rather than of a single one.

[1] Since Efremov's definition, taphonomy has expanded to include the fossilization of organic and inorganic materials through both cultural and environmental influences.

During the late twentieth century, taphonomic data began to be applied to other paleontological subfields such as paleobiology, paleoceanography, ichnology (the study of trace fossils) and biostratigraphy.

By coming to understand the oceanographic and ethological implications of observed taphonomic patterns, paleontologists have been able to provide new and meaningful interpretations and correlations that would have otherwise remained obscure in the fossil record.

The methodology of taphonomy involves observing transformation processes in order to understand their impact on archaeological material and interpret patterns on real sites.

Archaeologists typically separate natural from cultural processes when identifying evidence of human interaction with faunal remains.

While taphonomic methodology can be applied and used to study a variety of materials such as buried ceramics and lithics, its primary application in archaeology involves the examination of organic residues.

[4] Interpretation of the post-mortem, pre-, and post-burial histories of faunal assemblages is critical in determining their association with hominid activity and behaviour.

Brain in South Africa have shown that bone fractures previously attributed to "killer man-apes" were in fact caused by the pressure of overlying rocks and earth in limestone caves.

[25] His research has also demonstrated that early hominins, for example australopithecines, were more likely preyed upon by carnivores rather than being hunters themselves, from cave sites such as Swartkrans in South Africa.

[21] There are limitations to this kind of taphonomic study in archaeological deposits as any analysis has to presume that processes in the past were the same as today, e.g that living carnivores behaved in a similar way to those in prehistoric times.

[25] Since large bones survive better than plants this also has created a bias and inclination towards big-game hunting rather than gathering when considering prehistoric economies.

[31] In the later stages of the prolonged decomposition of the carcasses, the environment within the sarcophagus alters to more oxic and basic conditions promoting biomineralization and the precipitation of calcium carbonate.

[28] The microbes that constitute the microbial mats in addition to forming a sarcophagus, secrete an exopolymeric substances (EPS) that drive biomineralization.

[29] During later stages of decomposition heterotrophic microbes degrade the EPS, facilitating the release of calcium ions into the environment and creating a Ca-enriched film.

It is thus arguably the most important goal of taphonomy to identify the scope of such biases such that they can be quantified to allow correct interpretations of the relative abundances of organisms that make up a fossil biota.

As a result, animals with bones or shells are overrepresented in the fossil record, and many plants are only represented by pollen or spores that have hard walls.

The organisms of such habitats are also liable to be overrepresented in the fossil record than those living far from these aquatic environments where burial by sediments is unlikely to occur.

At a shorter scale, scouring processes such as the formation of ripples and dunes and the passing of turbidity currents may cause layers to be removed.

[citation needed] Much of the incompleteness of the fossil record is due to the fact that only a small amount of rock is ever exposed at the surface of the Earth, and not even most of that has been explored.

[34] Polysaccharides also have low preservation potential, unless they are highly cross-linked; this interconnection is most common in structural tissues, and renders them resistant to chemical decay.

[35] Such tissues include wood (lignin), spores and pollen (sporopollenin), the cuticles of plants (cutan) and animals, the cell walls of algae (algaenan),[35] and potentially the polysaccharide layer of some lichens.

[35] A peer-reviewed study in 2023 was the first to present an in-depth chemical description of how biological tissues and cells potentially preserve into the fossil record.

This study generalized the chemistry underlying cell and tissue preservation to explain the phenomenon for potentially any cellular organism.

The term taphomorph is used to collectively describe fossil structures that represent poorly-preserved and deteriorated remains of various taxonomic groups, rather than of a single species.

For example, the 579–560 million year old fossil Ediacaran assemblages from Avalonian locations in Newfoundland contain taphomorphs of a mixture of taxa which have collectively been named Ivesheadiomorphs.

Originally interpreted as fossils of a single genus, Ivesheadia, they are now thought to be the deteriorated remains of various types of frondose organism.

Similarly, Ediacaran fossils from England, once assigned to Blackbrookia, Pseudovendia and Shepshedia, are now all regarded as taphomorphs related to Charnia or Charniodiscus.

The processes an organism may undergo in a fluvial environment will result in a slower rate of decomposition within a river compared to on land.