Taphonomy

Taphonomy is the study of how organisms decay and become fossilized. The term taphonomy (from the Greek taphos, τάφος meaning "burial", and nomos, νόμος meaning "law") was introduced to paleontology in 1949[1] by Russian 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]

Description

Taphonomic phenomena are grouped into two phases: biostratinomy; events that occur between death of the organism and the burial, and diagenesis; events that occur after the burial.[1] Since Efremov's definition, taphonomy has expanded to include the fossilization of organic and inorganic materials through both cultural and environmental influences.

This is a multidisciplinary concept and is used in slightly different contexts throughout different fields of study. Fields that employ the concept of taphonomy include:

Skeleton in cave
An articulated wombat skeleton in Imperial-Diamond cave (Jenolan Caves)
LaBreaTarPitsExcavation2008
The La Brea Tar Pits represent an unusual depositional environment for their epoch (Pleistocene) and location (southern California).

There are five main stages of taphonomy: disarticulation, dispersal, accumulation, fossilization, and mechanical alteration.[4] The first stage, disarticulation, occurs as the organism decays and the bones are no longer held together by the flesh and tendons of the organism. Dispersal is the separation of pieces of an organism caused by natural events (i.e. floods, scavengers etc.). Accumulation occurs when there is a buildup of organic and/or inorganic materials in one location (scavengers or human behavior). When mineral rich groundwater permeates organic materials and fills the empty spaces, a fossil is formed. The final stage of taphonomy is mechanical alteration; these are the processes that physically alter the remains (i.e. freeze-thaw, compaction, transport, burial).[5] It should be added that these "stages" are not only successive, they interplay. For example, chemical changes occur at every stage of the process, because of bacteria. "Changes" begin as soon as the death of the organism: enzymes are released that destroy the organic contents of the tissues, and mineralised tissues such as bone, enamel and dentin are a mixture of organic and mineral components. Moreover, most often the organism (vegetal or animal) is dead because it has been "killed" by a predator. The digestion modifies the composition of the flesh, but also that of the bones.[6] [7]

Research areas

Taphonomy has undergone an explosion of interest since the 1980s,[8] with research focusing on certain areas.

  • Microbial, biogeochemical, and larger-scale controls on the preservation of different tissue types; in particular, exceptional preservation in Konzervat-lagerstätten. Covered within this field is the dominance of biological versus physical agents in the destruction of remains from all major taxonomic groups (plants, invertebrates, vertebrates).
  • Processes that concentrate biological remains; especially the degree to which different types of assemblages reflect the species composition and abundance of source faunas and floras.
  • The spatio-temporal resolution and ecological fidelity of species assemblages, particularly the relatively minor role of out-of-habitat transport contrasted with the major effects of time-averaging.
  • The outlines of megabiases in the fossil record, including the evolution of new bauplans and behavioral capabilities, and by broad-scale changes in climate, tectonics, and geochemistry of Earth surface systems.
  • The Mars Science Laboratory mission objectives evolved from assessment of ancient Mars habitability to developing predictive models on taphonomy.[9]

Paleontology

One motivation behind taphonomy is to understand biases present in the fossil record better. Fossils are ubiquitous in sedimentary rocks, yet paleontologists cannot draw the most accurate conclusions about the lives and ecology of the fossilized organisms without knowing about the processes involved in their fossilization. For example, if a fossil assemblage contains more of one type of fossil than another, one can infer either that the organism was present in greater numbers, or that its remains were more resistant to decomposition.

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.

Astrobiology

It has been suggested that biominerals could be important indicators of extraterrestrial life and thus could play an important role in the search for past or present life on the planet Mars. Furthermore, organic components (biosignatures) that are often associated with biominerals are believed to play crucial roles in both pre-biotic and biotic reactions.[10]

On January 24, 2014, NASA reported that current studies by the Curiosity and Opportunity rovers on Mars will now be searching for evidence of ancient life, including a biosphere based on autotrophic, chemotrophic and/or chemolithoautotrophic microorganisms, as well as ancient water, including fluvio-lacustrine environments (plains related to ancient rivers or lakes) that may have been habitable.[11][12][13][14] The search for evidence of habitability, taphonomy (related to fossils), and organic carbon on the planet Mars is now a primary NASA objective.[11][12]

Forensic science

Forensic taphonomy is a relatively new field that has increased in popularity in the past 15 years. It is a subfield of forensic anthropology focusing specifically on how taphonomic forces have altered criminal evidence.[15]

There are two different branches of forensic taphonomy: biotaphonomy and geotaphonomy. Biotaphonomy looks at how the decomposition and/or destruction of the organism has happened. The main factors that affect this branch are categorized into three groups: environmental factors; external variables, individual factors; factors from the organism itself (i.e. body size, age, etc.), and cultural factors; factors specific to any cultural behaviors that would affect the decomposition (burial practices). Geotaphonomy studies how the burial practices and the burial itself affects the surrounding environment. This includes soil disturbances and tool marks from digging the grave, disruption of plant growth and soil pH from the decomposing body, and the alteration of the land and water drainage from introducing an unnatural mass to the area.[16]

This field is extremely important because it helps scientists use the taphonomic profile to help determine what happened to the remains at the time of death (perimortem) and after death (postmortem). This can make a huge difference when considering what can be used as evidence in a criminal investigation.[17]

Environmental archaeology

Archaeologists study taphonomic processes in order to determine how plant and animal (including human) remains accumulate and differentially preserve within archaeological sites. Environmental archaeology is a multidisciplinary field of study that focuses on understanding the past relationships between groups and their environments. The main subfields of environmental archaeology include zooarchaeology, paleobotany, and geoarchaeology. Taphonomy allows specialists to identify what artifacts or remains encountered before and after initial burial. Zooarchaeology, a focus within environmental archaeology investigates taphonomic processes on animal remains. The processes most commonly identified within zooarchaeology include thermal alteration (burns), cut marks, worked bone, and gnaw marks.[18] Thermally altered bone indicate the use of fire and animal processing. Cut marks and worked bone can inform zooarchaeologists on tool use or food processing.[19] When there is little to no written record, taphonomy allows environmental archaeologists to better comprehend the ways in which a group interacted with their surrounding environments and inhabitants.

The field of environmental archaeology provides crucial information for attempting to understand the resilience of past societies and the great impacts that environmental shifts can have on a population. Knowledge gained from the past through these studies can be used to inform present and future decisions for human-environment interactions.

Taphonomic biases in the fossil record

Because of the very select processes that cause preservation, not all organisms have the same chance of being preserved. Any factor that affects the likelihood that an organism is preserved as a fossil is a potential source of bias. 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.[20] Some of the most common sources of bias are listed below.

Physical attributes of the organism itself

This perhaps represents the biggest source of bias in the fossil record. First and foremost, organisms that contain hard parts have a far greater chance of being represented in the fossil record than organisms consisting of soft tissue only. 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. Soft bodied organisms may form 30% to 100% of the biota, but most fossil assemblages preserve none of this unseen diversity, which may exclude groups such as fungi and entire animal phyla from the fossil record.{{[21]=June 2013}} Many animals that moult, on the other hand, are overrepresented, as one animal may leave multiple fossils due to its discarded body parts. Among plants, wind-pollinated species produce so much more pollen than animal-pollinated species, that the former are much overrepresented relative to the latter.

Characteristics of the habitat

Most fossils form in conditions where material is deposited to the bottom of water bodies. Especially shallow sea coasts produce large amounts of fossils, so organisms living in such conditions have a much higher chance of being preserved as fossils than organisms living in non-depositing conditions. In continental environments, fossilization is especially likely in small lakes that gradually fill in with organic and inorganic material and especially in peat-accumulating wetlands. The organisms of such habitats are therefore overrepresented in the fossil record.

Mixing of fossils from different places

A sedimentary deposit may have experienced a mixing of noncontemporaneous remains within single sedimentary units via physical or biological processes; i.e. a deposit could be ripped up and redeposited elsewhere, meaning that a deposit may contain a large amount of fossils from another place (an allochthonous deposit, as opposed to the usual autochthonous). Thus, a question that is often asked of fossil deposits is to what extent does the fossil deposit record the true biota that originally lived there? Many fossils are obviously autochthonous, such as rooted fossils like crinoids, and many fossils are intrisically obviously allocthonous, such as the presence of photoautotrophic plankton in a benthic deposit that must have sunk to be deposited. A fossil deposit may thus become biased towards exotic species (i.e. species not endemic to that area) when the sedimentology is dominated by gravity driven surges, such as mudslides, or may become biased if there is very little endemic organisms to be preserved. This is a particular problem in palynology.

Temporal resolution

Because population turnover rates of individual taxa are much less than net rates of sediment accumulation, the biological remains of successive, noncontemporaneous populations of organisms may be admixed within a single bed, known as time-averaging. Because of the slow and episodic nature of the geologic record, two apparently contemporaneous fossils may have actually lived centuries, or even millennia, apart. Moreover, the degree of time averaging in an assemblage may vary. The degree varies on many factors, such as tissue type, the habitat, the frequency of burial events and exhumation events, and the depth of bioturbation within the sedimentary column relative to net sediment accumulation rates. Like biases in spatial fidelity, there is a bias towards organisms that can survive reworking events, such as shells. An example of a more ideal deposit with respect to time-averaging bias would be a volcanic ash deposit, which captures an entire biota caught in the wrong place at the wrong time (e.g. the Silurian Herefordshire lagerstätte).

Gaps in time series

The geological record is very discontinuous, and deposition is episodic at all scales. At the largest scale, a sedimentological high-stand period may mean that no deposition may occur for millions of years and, in fact, erosion of the deposit may occur. Such a hiatus is called an unconformity. Conversely, a catastrophic event such as a mudslide may overrepresent a time period. 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. Thus the fossil record is biased towards periods of greatest sedimentation; periods of time that have less sedimentation are consequently less well represented in the fossil record.

A related problem is the slow changes that occur in the depositional environment of an area; a deposit may experience periods of poor preservation due to, for example, a lack of biomineralizing elements. This causes the taphonomic or diagenetic obliteration of fossils, producing gaps and condensation of the record.

Consistency in preservation over geologic time

Major shifts in intrinsic and extrinsic properties of organisms, including morphology and behavior in relation to other organisms or shifts in the global environment, can cause secular or long-term cyclic changes in preservation (megabias).

Human biases

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. Our fossil record relies on the small amount of exploration that has been done on this. Unfortunately, paleontologists as humans can be very biased in their methods of collection; a bias that must be identified. Potential sources of bias include,

  • Search images: field experiments have shown that paleontologists working on, say fossil clams are better at collecting clams than anything else, because their search image has been shaped to bias them in favour of clams.
  • Relative ease of extraction: fossils that are easy to obtain (such as many phosphatic fossils that are easily extracted en masse by dissolution in acid) are overabundant in the fossil record.
  • Taxonomic bias: fossils with easily discernible morphologies will be easy to distinguish as separate species, and will thus have an inflated abundance.

Preservation of biopolymers

ElrathiakingiUtahWheelerCambrian
Although chitin exoskeletons of arthropods such as insects and myriapods (but not trilobites, which are mineralized with calcium carbonate, nor crustaceans, which are often mineralized with calcium phosphate) are subject to decomposition, they often maintain shape during permineralization, especially if they are already somewhat mineralized.

The taphonomic pathways involved in relatively inert substances such as calcite (and to a lesser extent bone) are relatively obvious, as such body parts are stable and change little through time. However, the preservation of "soft tissue" is more interesting, as it requires more peculiar conditions. While usually only biomineralised material survives fossilisation, the preservation of soft tissue is not as rare as sometimes thought.[22]

Both DNA and proteins are unstable, and rarely survive more than hundreds of thousands of years before degrading.[23] Polysaccharides also have low preservation potential, unless they are highly cross-linked;[23] this interconnection is most common in structural tissues, and renders them resistant to chemical decay.[23] Such tissues include wood (lignin), spores and pollen (sporopollenin), the cuticles of plants (cutan) and animals, the cell walls of algae (algaenan),[23] and potentially the polysaccharide layer of some lichens. This interconnectedness makes the chemicals less prone to chemical decay, and also means they are a poorer source of energy so less likely to be digested by scavenging organisms.[23] After being subjected to heat and pressure, these cross-linked organic molecules typically "cook" and become kerogen or short (<17 C atoms) aliphatic/aromatic carbon molecules.[23] Other factors affect the likelihood of preservation; for instance scleritisation renders the jaws of polychaetes more readily preserved than the chemically equivalent but non-sclerotised body cuticle.[23]

It was thought that only tough, cuticle type soft tissue could be preserved by Burgess Shale type preservation,[24] but an increasing number of organisms are being discovered that lack such cuticle, such as the probable chordate Pikaia and the shellless Odontogriphus.[25]

It is a common misconception that anaerobic conditions are necessary for the preservation of soft tissue; indeed much decay is mediated by sulfate reducing bacteria which can only survive in anaerobic conditions.[23] Anoxia does, however, reduce the probability that scavengers will disturb the dead organism, and the activity of other organisms is undoubtedly one of the leading causes of soft-tissue destruction.[23]

Plant cuticle is more prone to preservation if it contains cutan, rather than cutin.[23]

Plants and algae produce the most preservable compounds, which are listed according to their preservation potential by Tegellaar (see reference).[26]

Disintegration

How complete fossils are was once thought to be a proxy for the energy of the environment, with stormier waters leaving less articulated carcasses. However, the dominant force actually seems to be predation, with scavengers more likely than rough waters to break up a fresh carcass before it is buried.[27] Sediments cover smaller fossils faster so they are likely to be found fully articulated. However, erosion also tends to destroy smaller fossils more easily.[28]

Significance

Taphonomic processes allow researchers of multiple fields to identify the past of natural and cultural objects. From the time of death or burial until excavation, taphonomy can aid in the understanding of past environments.[29] When studying the past it is important to gain contextual information in order to have a solid understanding of the data. Often these findings can be used to better understand cultural or environmental shifts within the present day.

See also

References

  1. ^ a b Lyman, R. Lee (2010-01-01). "What Taphonomy Is, What it Isn't, and Why Taphonomists Should Care about the Difference". Journal of Taphonomy. 8 (1): 1–16. ISSN 1696-0815.
  2. ^ Efremov, I. A. (1940). "Taphonomy: a new branch of paleontology". Pan-American Geology. 74: 81–93. Archived from the original on 2008-04-03.
  3. ^ Martin, Ronald E. (1999) "1.1 The foundations of taphonomy" Taphonomy: A Process Approach Cambridge University Press, Cambridge, England, p. 1, ISBN 0-521-59833-8
  4. ^ "TAPHONOMY". personal.colby.edu. Retrieved 2017-05-03.
  5. ^ "Taphonomy & Preservation". paleo.cortland.edu. Archived from the original on 2017-05-17. Retrieved 2017-05-03.
  6. ^ Brugal J.P. Coordinateur (2017-07-01). TaphonomieS. GDR 3591, CNRS INEE. Paris: Archives contemporaines. ISBN 978-2813002419. OCLC 1012395802.
  7. ^ Dauphin Y. (2014). in: Manuel de taphonomie. Denys C., Patou-Mathis M. coordinatrices. Arles: Errance. ISBN 9782877725774. OCLC 892625160.
  8. ^ Behrensmeyer, A. K; S. M Kidwell; R. A Gastaldo (2009), Taphonomy and paleobiology.
  9. ^ Grotzinger, John P. (24 January 2014). "•Introduction to Special Issue: Habitability, Taphonomy, and the Search for Organic Carbon on Mars". Science. 343 (6169): 386–387. Bibcode:2014Sci...343..386G. doi:10.1126/science.1249944. PMID 24458635. Retrieved 2014-01-24.
  10. ^ Steele, Andrew; Beaty, David, eds. (September 26, 2006). "Final report of the MEPAG Astrobiology Field Laboratory Science Steering Group (AFL-SSG)". The Astrobiology Field Laboratory. U.S.A.: Mars Exploration Program Analysis Group (MEPAG) – NASA. p. 72.
  11. ^ a b Grotzinger, John P. (January 24, 2014). "Introduction to Special Issue – Habitability, Taphonomy, and the Search for Organic Carbon on Mars". Science. 343 (6169): 386–387. Bibcode:2014Sci...343..386G. doi:10.1126/science.1249944. PMID 24458635. Retrieved January 24, 2014.
  12. ^ a b Various (January 24, 2014). "Special Issue - Table of Contents - Exploring Martian Habitability". Science. 343 (6169): 345–452. Retrieved January 24, 2014.CS1 maint: Uses authors parameter (link)
  13. ^ Various (January 24, 2014). "Special Collection – Curiosity – Exploring Martian Habitability". Science. Retrieved January 24, 2014.CS1 maint: Uses authors parameter (link)
  14. ^ Grotzinger, J.P. et al. (January 24, 2014). "A Habitable Fluvio-Lacustrine Environment at Yellowknife Bay, Gale Crater, Mars". Science. 343 (6169): 1242777. Bibcode:2014Sci...343A.386G. CiteSeerX 10.1.1.455.3973. doi:10.1126/science.1242777. PMID 24324272. Retrieved January 24, 2014.CS1 maint: Uses authors parameter (link)
  15. ^ Passalacqua, Nicholas. "Introduction to Part VI: Forensic taphonomy".
  16. ^ admin (2011-12-08). "Forensic taphonomy". Crime Scene Investigator (CSI) and forensics information.
  17. ^ Pokines, James; Symes, Steven A. (2013). Front Matter. Manual of Forensic Taphonomy. pp. i–xiv. doi:10.1201/b15424-1. ISBN 978-1-4398-7841-5.
  18. ^ Fernandez Jalvo, Yolanda and Peter Andrews, “Methods in Taphonomy” in Atlas of Taphonomic Identifications: 1001+ Images of Fossil and Recent Mammal Bone Modification, ed. Eric Delson and Eric J. Sargis Vertebrate Paleobiology and Paleoanthropology Series (New York, NY, American Museum of Natural History, 2016).
  19. ^ Rainsford C., and O'Connor T. 2016. "Taphonomy and Contextual Zooarchaeology in Urban Deposits at York, UK." Archaeological and Anthropological Sciences 8 (2): 343–351. doi:10.1007/s12520-015-0268-x.
  20. ^ Kidwell, S. M.; P. J Brenchley; D. Jablonski; D. H. Erwin; J. H. Lipps (1996), "Evolution of the fossil record: thickness trends in marine skeletal accumulations and their implications", Evolutionary Paleobiology: In Honor of James W. Valentine: 290
  21. ^ http://search.ebscohost.com/login.aspx?direct=true&db=a9h&AN=96859831&site=eds-live&scope=site&profile=eds-main
  22. ^ Briggs, D.E.G.; Kear, A.J. (1993), "Decay and preservation of polychaetes; taphonomic thresholds in soft-bodied organisms", Paleobiology, 19 (1): 107–135, doi:10.1017/S0094837300012343
  23. ^ a b c d e f g h i j Briggs, D.E.G. (1999), "Molecular taphonomy of animal and plant cuticles: selective preservation and diagenesis", Philosophical Transactions of the Royal Society B: Biological Sciences, 354 (1379): 7–17, doi:10.1098/rstb.1999.0356, PMC 1692454
  24. ^ Butterfield, N.J. (1990), "Organic preservation of non-mineralizing organisms and the taphonomy of the Burgess Shale", Paleobiology, 16 (3): 272–286, doi:10.1017/S0094837300009994, JSTOR 2400788
  25. ^ Conway Morris, S. (2008), "A Redescription of a Rare Chordate, Metaspriggina walcotti Simonetta and Insom, from the Burgess Shale (Middle Cambrian), British Columbia, Canada", Journal of Paleontology, 82 (2): 424–430, doi:10.1666/06-130.1
  26. ^ Tegelaar, E.W.; De Leeuw, J.W.; Derenne, S.; Largeau, C. (1989), "A reappraisal of kerogen formation", Geochim. Cosmochim. Acta, 53 (3): 03–3106, Bibcode:1989GeCoA..53.3103T, doi:10.1016/0016-7037(89)90191-9
  27. ^ Behrensmeyer, A. K.; Kidwell, S. M.; Gastaldo, R. A. (2000). "Taphonomy and Paleobiology". Paleobiology. 26 (4): 103–147. doi:10.1666/0094-8373(2000)26[103:TAP]2.0.CO;2. ISSN 0094-8373.
  28. ^ http://search.ebscohost.com/login.aspx?direct=true&db=geh&AN=2004-032139&site=eds-live&scope=site&profile=eds-main
  29. ^ Lyman, R. Lee. Vertebrate taphonomy. Cambridge: Cambridge University Press, 1994.

Further reading

  • Emig, C. C. (2002). "Death: a key information in marine palaeoecology" in Current topics on taphonomy and fossilization, Valencia". Col.lecio Encontres. 5: 21–26.
  • Greenwood, D. R. (1991), "The taphonomy of plant macrofossils". In, Donovan, S. K. (Ed.), The processes of fossilisation, p. 141–169. Belhaven Press.
  • Lyman, R. L. (1994), Vertebrate Taphonomy. Cambridge University Press.
  • Shipman, P. (1981), Life history of a fossil: An introduction to taphonomy and paleoecology. Harvard University Press.
  • Taylor, P. D.; Wilson, M. A. (2003). "Palaeoecology and evolution of marine hard substrate communities" (PDF). Earth-Science Reviews. 62 (1–2): 1–103. Bibcode:2003ESRv...62....1T. doi:10.1016/s0012-8252(02)00131-9. Archived from the original (PDF) on 2009-03-25.

External links

Athyris

Athyris is a brachiopod genus with a subequally biconvex shell that is generally wider than long and a range that extends from the Silurian into the Triassic. Athyris is the type genus for the Athyrididae, which belongs to the articulate order Athyridida. R.C. Moore (1952) gives a shorter range, from the Mid Devonian to the Lower Mississippian.

Alverezites, Bruntonites, and Meristospira are among related genera.

Barapasaurus

Barapasaurus ( bə-RAH-pə-SAWR-əs) is a genus of basal sauropod dinosaur from Early Jurassic rocks of India. The only species is B. tagorei. Barapasaurus comes from the lower part of the Kota Formation, that dates back to the Sinemurian and Pliensbachian stages of the early Jurassic. It is therefore one of the earliest known sauropods. Barapasaurus is known from approximately 300 bones from at least six individuals, so that the skeleton is almost completely known except for the anterior cervical vertebrae and the skull. This makes Barapasaurus one of the most completely known sauropods from the early Jurassic.

Biostratinomy

Biostratinomy is the study of the processes that take place after an organism dies but before its final burial. It is considered to be a subsection of the science of taphonomy, along with necrology (the study of the death of an organism) and diagenesis (the changes that take place after final burial). These processes are largely destructive, and include physical, chemical and biological effects:

Physical effects non-exhaustively include transport, breakage and exhumation.

Chemical effects include early changes in mineralogy and oxidation.

Biological effects include decay, scavenging, bioturbation, encrustation and boring.For the vast majority of organisms, biostratinomic destruction is total. However, if at least a few remnants of an organism make it to final burial, a fossil may eventually be formed unless destruction is completed by diagenesis. As the processes of biostratinomy are often dominated by sedimentological factors, analysis of the biostratinomy of a fossil can reveal important features about the physical environment it once lived in. The boundaries between the three disciplines within taphonomy are partly arbitrary. In particular, the role of microbes in sealing and preserving organisms, for example in a process called autolithification, is now recognised to be a very important and early event in the preservation of many exceptional fossils, often taking place before burial. Such mineralogical changes might equally be considered to be biostratinomic as diagenetic.

A school of investigation called Aktuopaläontologie, subsisting largely in Germany, attempts to investigate biostratinomic effects by experimentation and observation on extant organisms. William Schäfer's book "Ecology and palaeoecology of marine environments" is a classic product of this sort of investigation. More recently, D.E.G. Briggs and colleagues have made detailed studies of decay with the prime aim of understanding the profound halt to these processes that is required by exceptional preservation in lagerstätten.

Burgess Shale

The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At 508 million years (middle Cambrian) old, it is one of the earliest fossil beds containing soft-part imprints.

The rock unit is a black shale and crops out at a number of localities near the town of Field in Yoho National Park and the Kicking Horse Pass. Another outcrop is in Kootenay National Park 42 km to the south.

Cephalopod egg fossil

Cephalopod egg fossils are the fossilized remains of eggs laid by cephalopods. The fossil record of cephalopod eggs is scant since their soft, gelatinous eggs decompose quickly and have little chance to fossilize. Eggs laid by ammonoids are the best known and only a few putative examples of these have been discovered. The best preserved of these were discovered in the Jurassic Kimmeridge Clay of England. Currently no belemnoid egg fossils have ever been discovered although this may be because scientists have not properly searched for them rather than an actual absence from the fossil record.

Daemonosaurus

Daemonosaurus (pron.:"DAY-mow-no-SORE-us") is an extinct genus of theropod dinosaur from the Late Triassic of New Mexico. Fossils have been found from deposits in the Chinle Formation, which is latest Triassic in age. While theropods had diversified into several specialized groups by this time, Daemonosaurus is a basal theropod that lies outside the clade Neotheropoda. Daemonosaurus is unusual among early theropods in that it had a short skull and long protruding teeth.

Decomposition

Decomposition is the process by which organic substances are broken down into simpler organic matter. The process is a part of the nutrient cycle and is essential for recycling the finite matter that occupies physical space in the biosphere. Bodies of living organisms begin to decompose shortly after death. Animals, such as worms, also help decompose the organic materials. Organisms that do this are known as decomposers. Although no two organisms decompose in the same way, they all undergo the same sequential stages of decomposition. The science which studies decomposition is generally referred to as taphonomy from the Greek word taphos, meaning tomb.

One can differentiate abiotic from biotic substance (biodegradation). The former means "degradation of a substance by chemical or physical processes, e.g., hydrolysis. The latter means "the metabolic breakdown of materials into simpler components by living organisms", typically by microorganisms.

Egg taphonomy

Egg taphonomy is the study of the decomposition and fossilization of eggs. The processes of egg taphonomy begin when the egg either hatches or dies. Eggshell fragments are robust and can often travel great distances before burial. More complete egg specimens gradually begin to fill with sediment, which hardens as minerals precipitate out of water percolating through pores or cracks in the shell. Throughout the fossilization process the calcium carbonate composing the eggshell generally remains unchanged, allowing scientists to study its original structure. However, egg fossils buried under sediments at great depth can be subjected to heat, pressure and chemical processes that can alter the structure of its shell through a process called diagenesis.

Elands Bay Cave

Elands Bay Cave is located near the mouth of the Verlorenvlei estuary on the Atlantic coast of South Africa's Western Cape Province. The climate has continuously become drier since the habitation of hunter-gatherers in the Later Pleistocene. The archaeological remains recovered from previous excavations at Elands Bay Cave have been studied to help answer questions regarding the relationship of people and their landscape, the role of climate change that could have determined or influenced subsistence changes, and the impact of pastoralism and agriculture on hunter-gatherer communities.

Forensic anthropology

Forensic anthropology is the application of the anatomical science of anthropology and its various subfields, including forensic archaeology and forensic taphonomy, in a legal setting. A forensic anthropologist can assist in the identification of deceased individuals whose remains are decomposed, burned, mutilated or otherwise unrecognizable, as might happen in a plane crash. Forensic anthropologists are also instrumental to the investigation and documentation of genocide and mass graves. Along with forensic pathologists, forensic dentists, and homicide investigators, forensic anthropologists commonly testify in court as expert witnesses. Using physical markers present on a skeleton, a forensic anthropologist can potentially determine a victim's age, sex, stature, and ancestry. In addition to identifying physical characteristics of the individual, forensic anthropologists can use skeletal abnormalities to potentially determine cause of death, past trauma such as broken bones or medical procedures, as well as diseases such as bone cancer.

The methods used to identify a person from a skeleton relies on the past contributions of various anthropologists and the study of human skeletal differences. Through the collection of thousands of specimens and the analysis of differences within a population, estimations can be made based on physical characteristics. Through these, a set of remains can potentially be identified. The field of forensic anthropology grew during the twentieth century into a fully recognized forensic specialty involving trained anthropologists as well as numerous research institutions gathering data on decomposition and the effects it can have on the skeleton.

Ivan Yefremov

Ivan Antonovich (real patronymic Antipovich) Yefremov (Russian: Ива́н Анто́нович (Анти́пович) Ефре́мов; April 22, 1908 – October 5, 1972), last name sometimes spelled Efremov, was a Soviet paleontologist, science fiction author and social thinker. He is the originator of the concept of taphonomy, the study of fossilization patterns.

Lotosaurus

Lotosaurus is an extinct genus of sail-backed poposauroid known from Hunan Province of central China.

Mars rover

A Mars rover is a motor vehicle that travels across the surface of the planet Mars upon arrival. Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control.

There have been four successful robotically operated Mars rovers, all managed by the Jet Propulsion Laboratory: Sojourner, Opportunity, Spirit and Curiosity. On January 24, 2016, NASA reported that current studies on Mars by Curiosity and Opportunity (the latter now defunct) would be searching for evidence of ancient life, including a biosphere based on autotrophic, chemotrophic or chemolithoautotrophic microorganisms, as well as ancient water, including fluvio-lacustrine environments (plains related to ancient rivers or lakes) that may have been habitable. The search for evidence of habitability, taphonomy (related to fossils), and organic carbon on Mars is now a primary NASA objective. In June 2018, Opportunity went out of contact after going into hibernation mode in a dust storm. NASA declared the end of the Opportunity mission on February 13, 2019, after numerous failures to wake up the rover.Mars 2, Mars 3 were physically tethered probes; Sojourner was dependent on the Mars Pathfinder base station for communication with Earth; MER-A & B and Curiosity were on their own. As of June 2019, Curiosity is still active, while Spirit, Opportunity, and Sojourner completed their missions before losing contact.

Metoposauridae

Metoposauridae is an extinct family of trematosaurian temnospondyls. The family is known from the Triassic period. Most members are large, approximately 1.5 metres (4.9 ft) long and could reach 3 m long. Metoposaurids can be distinguished from the very similar mastodonsauroids by the position of their eyes, placed far forward on the snout.

Palaeontology (journal)

Palaeontology is one of the two scientific journals of the Palaeontological Association (the other being Papers in Palaeontology). It was established in 1957 and is published on behalf of the Association by Wiley-Blackwell. The editor-in-chief is Andrew Smith (Natural History Museum, London). Palaeontology publishes articles on a range of palaeontological topics, including taphonomy, functional morphology, systematics, palaeo-environmental reconstruction and biostratigraphy. According to the Journal Citation Reports, the journal has a 2017 impact factor of 3.730, ranking it 1st out of 55 journals in the category "Paleontology".

Phyllopod bed

The Phyllopod bed, designated by USNM locality number 35k, is the most famous fossil-bearing member of the Burgess shale fossil Lagerstätte. It was quarried by Charles Walcott from 1911–1917 (and later named Walcott Quarry), and was the source of 95% of the fossils he collected during this time;

tens of thousands of soft-bodied fossils representing over 150 genera have been recovered from the Phyllopod bed alone.

Pisidium

Pisidium is a genus of very small or minute freshwater clams known as pill clams or pea clams, aquatic bivalve molluscs in the family Sphaeriidae, the pea clams and fingernail clams.

In some bivalve classification systems, the family Sphaeriidae is referred to as Pisidiidae, and occasionally Pisidium species are grouped in a subfamily known as Pisidiinae.

Segisaurus

Segisaurus (meaning "Segi canyon lizard") is a genus of small coelophysoid theropod dinosaur, that measured approximately 1 metre (3.3 feet) in length. The only known specimen was discovered in early Jurassic strata in Tsegi Canyon, Arizona, for which it was named. Segisaurus is the only dinosaur to have ever been excavated from the area.

Soumyasaurus

Soumyasaurus is a small silesaurid dinosauriform from the Late Triassic (Norian) Cooper Canyon Formation of western Texas.

Chemical weathering
Physical weathering
Related topics
Cenozoic era
(present–66.0 Mya)
Mesozoic era
(66.0–251.902 Mya)
Paleozoic era
(251.902–541.0 Mya)
Proterozoic eon
(541.0 Mya–2.5 Gya)
Archean eon (2.5–4 Gya)
Hadean eon (4–4.6 Gya)

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