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Fossil

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Montage of multiple fossil taxa. Clockwise from top left: Onychocrinus and Palaeosinopa; bottom row: Gryphaea and Harpactocarcinus
Montage of multiple fossil taxa. Clockwise from top left: Onychocrinus and Palaeosinopa; bottom row: Gryphaea and Harpactocarcinus

A fossil (from Classical Latin fossilis, lit.'obtained by digging')[1] is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the fossil record.

Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old.[2] The oldest fossils are around 3.48 billion years old[3][4][5] to 4.1 billion years old.[6][7] The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ages of rocks and the fossils they host.

There are many processes that lead to fossilization, including permineralization, casts and molds, authigenic mineralization, replacement and recrystallization, adpression, carbonization, and bioimmuration.

Fossils vary in size from one-micrometre (1 µm) bacteria[8] to dinosaurs and trees, many meters long and weighing many tons. A fossil normally preserves only a portion of the deceased organism, usually that portion that was partially mineralized during life, such as the bones and teeth of vertebrates, or the chitinous or calcareous exoskeletons of invertebrates. Fossils may also consist of the marks left behind by the organism while it was alive, such as animal tracks or feces (coprolites). These types of fossil are called trace fossils or ichnofossils, as opposed to body fossils. Some fossils are biochemical and are called chemofossils or biosignatures.

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Classical Latin

Classical Latin

Classical Latin is the form of Literary Latin recognized as a literary standard by writers of the late Roman Republic and early Roman Empire. It was used from 75 BC to the 3rd century AD, when it developed into Late Latin. In some later periods, it was regarded as good or proper Latin, with following versions viewed as debased, degenerate, or corrupted. The word Latin is now understood by default to mean "Classical Latin"; for example, modern Latin textbooks almost exclusively teach Classical Latin.

Bone

Bone

A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility. Bones come in a variety of shapes and sizes and have complex internal and external structures. They are lightweight yet strong and hard and serve multiple functions.

DNA

DNA

Deoxyribonucleic acid is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.

Evolution

Evolution

In biology, evolution is the change in heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation.

Authigenesis

Authigenesis

Authigenesis is the process whereby a mineral or sedimentary rock deposit is generated where it is found or observed. Such deposits are described as authigenic. Authigenic sedimentary minerals form during sedimentation by precipitation or recrystallization instead of being transported from elsewhere (allogenic) by water or wind. Authigenic sediments are the main constituents of deep sea sedimentation. Authigenic clays tend to reduce the porosity of sediments, thus reducing permeability.

Carbonization

Carbonization

Carbonization is the conversion of organic matters like plants and dead animal remains into carbon through destructive distillation.

Dinosaur

Dinosaur

Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 245 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds.

Chitin

Chitin

Chitin (C8H13O5N)n ( KY-tin) is a long-chain polymer of N-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chitin are produced each year in the biosphere. It is a primary component of cell walls in fungi (especially basidiomycetes and filamentous fungi), the exoskeletons of arthropods such as crustaceans and insects, the radulae, cephalopod beaks and gladii of molluscs and in some nematodes and diatoms. It is also synthesised by at least some fish and lissamphibians. Commercially, chitin is extracted from the shells of crabs, shrimps, shellfish and lobsters, which are major by-products of the seafood industry. The structure of chitin is comparable to cellulose, forming crystalline nanofibrils or whiskers. It is functionally comparable to the protein keratin. Chitin has proved useful for several medicinal, industrial and biotechnological purposes.

Calcareous

Calcareous

Calcareous is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.

Coprolite

Coprolite

A coprolite is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour rather than morphology. The name is derived from the Greek words κόπρος and λίθος. They were first described by William Buckland in 1829. Before this, they were known as "fossil fir cones" and "bezoar stones". They serve a valuable purpose in paleontology because they provide direct evidence of the predation and diet of extinct organisms. Coprolites may range in size from a few millimetres to over 60 centimetres.

Biochemistry

Biochemistry

Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells, in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.

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 or chemical structures and its use of free energy and the production of biomass and wastes. A biosignature can provide evidence for living organisms outside the Earth and can be directly or indirectly detected by searching for their unique byproducts.

Reliability

Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give us a good understanding of the pattern of diversification of life on Earth.[9][10][11] In addition, the record can predict and fill gaps such as the discovery of Tiktaalik in the arctic of Canada.[12]

Fossilization processes

The process of fossilization varies according to tissue type and external conditions:

Permineralization

Permineralized bryozoan from the Devonian of Wisconsin.
Permineralized bryozoan from the Devonian of Wisconsin.

Permineralization is a process of fossilization that occurs when an organism is buried. The empty spaces within an organism (spaces filled with liquid or gas during life) become filled with mineral-rich groundwater. Minerals precipitate from the groundwater, occupying the empty spaces. This process can occur in very small spaces, such as within the cell wall of a plant cell. Small scale permineralization can produce very detailed fossils.[13] For permineralization to occur, the organism must become covered by sediment soon after death, otherwise the remains are destroyed by scavengers or decomposition.[14] The degree to which the remains are decayed when covered determines the later details of the fossil. Some fossils consist only of skeletal remains or teeth; other fossils contain traces of skin, feathers or even soft tissues.[15] This is a form of diagenesis.

Casts and molds

External mold of a bivalve from the Logan Formation, Lower Carboniferous, Ohio
External mold of a bivalve from the Logan Formation, Lower Carboniferous, Ohio

In some cases, the original remains of the organism completely dissolve or are otherwise destroyed. The remaining organism-shaped hole in the rock is called an external mold. If this void is later filled with sediment, the resulting cast resembles what the organism looked like. An endocast, or internal mold, is the result of sediments filling an organism's interior, such as the inside of a bivalve or snail or the hollow of a skull.[16] Endocasts are sometimes termed Steinkerns, especially when bivalves are preserved this way.[17]

Authigenic mineralization

This is a special form of cast and mold formation. If the chemistry is right, the organism (or fragment of organism) can act as a nucleus for the precipitation of minerals such as siderite, resulting in a nodule forming around it. If this happens rapidly before significant decay to the organic tissue, very fine three-dimensional morphological detail can be preserved. Nodules from the Carboniferous Mazon Creek fossil beds of Illinois, USA, are among the best documented examples of such mineralization.[18]

Replacement and recrystallization

Silicified (replaced with silica) fossils from the Road Canyon Formation (Middle Permian of Texas)
Silicified (replaced with silica) fossils from the Road Canyon Formation (Middle Permian of Texas)
Recrystallized scleractinian coral (aragonite to calcite) from the Jurassic of southern Israel
Recrystallized scleractinian coral (aragonite to calcite) from the Jurassic of southern Israel

Replacement occurs when the shell, bone, or other tissue is replaced with another mineral. In some cases mineral replacement of the original shell occurs so gradually and at such fine scales that microstructural features are preserved despite the total loss of original material. A shell is said to be recrystallized when the original skeletal compounds are still present but in a different crystal form, as from aragonite to calcite.[19]

Adpression (compression-impression)

Compression fossils, such as those of fossil ferns, are the result of chemical reduction of the complex organic molecules composing the organism's tissues. In this case the fossil consists of original material, albeit in a geochemically altered state. This chemical change is an expression of diagenesis. Often what remains is a carbonaceous film known as a phytoleim, in which case the fossil is known as a compression. Often, however, the phytoleim is lost and all that remains is an impression of the organism in the rock—an impression fossil. In many cases, however, compressions and impressions occur together. For instance, when the rock is broken open, the phytoleim will often be attached to one part (compression), whereas the counterpart will just be an impression. For this reason, one term covers the two modes of preservation: adpression.[20]

Soft tissue, cell and molecular preservation

Because of their antiquity, an unexpected exception to the alteration of an organism's tissues by chemical reduction of the complex organic molecules during fossilization has been the discovery of soft tissue in dinosaur fossils, including blood vessels, and the isolation of proteins and evidence for DNA fragments.[21][22][23][24] In 2014, Mary Schweitzer and her colleagues reported the presence of iron particles (goethite-aFeO(OH)) associated with soft tissues recovered from dinosaur fossils. Based on various experiments that studied the interaction of iron in haemoglobin with blood vessel tissue they proposed that solution hypoxia coupled with iron chelation enhances the stability and preservation of soft tissue and provides the basis for an explanation for the unforeseen preservation of fossil soft tissues.[25] However, a slightly older study based on eight taxa ranging in time from the Devonian to the Jurassic found that reasonably well-preserved fibrils that probably represent collagen were preserved in all these fossils and that the quality of preservation depended mostly on the arrangement of the collagen fibers, with tight packing favoring good preservation.[26] There seemed to be no correlation between geological age and quality of preservation, within that timeframe.

Carbonization and coalification

Fossils that are carbonized or coalified consist of the organic remains which have been reduced primarily to the chemical element carbon. Carbonized fossils consist of a thin film which forms a silhouette of the original organism, and the original organic remains were typically soft tissues. Coalified fossils consist primarily of coal, and the original organic remains were typically woody in composition.

Bioimmuration

The star-shaped holes (Catellocaula vallata) in this Upper Ordovician bryozoan represent a soft-bodied organism preserved by bioimmuration in the bryozoan skeleton.[27]
The star-shaped holes (Catellocaula vallata) in this Upper Ordovician bryozoan represent a soft-bodied organism preserved by bioimmuration in the bryozoan skeleton.[27]

Bioimmuration occurs when a skeletal organism overgrows or otherwise subsumes another organism, preserving the latter, or an impression of it, within the skeleton.[28] Usually it is a sessile skeletal organism, such as a bryozoan or an oyster, which grows along a substrate, covering other sessile sclerobionts. Sometimes the bioimmured organism is soft-bodied and is then preserved in negative relief as a kind of external mold. There are also cases where an organism settles on top of a living skeletal organism that grows upwards, preserving the settler in its skeleton. Bioimmuration is known in the fossil record from the Ordovician[29] to the Recent.[28]

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Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, 419.2 million years ago (Mya), to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, England, where rocks from this period were first studied.

Permineralization

Permineralization

Permineralization is a process of fossilization of bones and tissues in which mineral deposits form internal casts of organisms. Carried by water, these minerals fill the spaces within organic tissue. Because of the nature of the casts, permineralization is particularly useful in studies of the internal structures of organisms, usually of plants.

Groundwater

Groundwater

Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.

Cell wall

Cell wall

A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in many eukaryotes, including animals, but are present in some other ones like fungi, algae and plants, and in most prokaryotes. A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters.

Feather

Feather

Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premier example of a complex evolutionary novelty. They are among the characteristics that distinguish the extant birds from other living groups.

Diagenesis

Diagenesis

Diagenesis is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a role as sediments become buried much deeper in the Earth's crust. In the early stages, the transformation of poorly consolidated sediments into sedimentary rock (lithification) is simply accompanied by a reduction in porosity and water expulsion, while their main mineralogical assemblages remain unaltered. As the rock is carried deeper by further deposition above, its organic content is progressively transformed into kerogens and bitumens. The process of diagenesis excludes surface alteration (weathering) and deep metamorphism. There is no sharp boundary between diagenesis and metamorphism, but the latter occurs at higher temperatures and pressures. Hydrothermal solutions, meteoric groundwater, rock porosity, permeability, dissolution/precipitation reactions, and time are all influential factors.

Bivalvia

Bivalvia

Bivalvia, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bivalves have no head and they lack some usual molluscan organs, like the radula and the odontophore. The class includes the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some bivalves, such as the scallops and file shells, can swim. The shipworms bore into wood, clay, or stone and live inside these substances.

Logan Formation

Logan Formation

The Logan Formation is the name given to a Lower Carboniferous siltstone, sandstone and conglomeratic unit exposed in east-central Ohio and parts of western West Virginia, USA.

Carboniferous

Carboniferous

The Carboniferous is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 million years ago (Mya), to the beginning of the Permian Period, 298.9 million years ago. The name Carboniferous means "coal-bearing", from the Latin carbō ("coal") and ferō, and refers to the many coal beds formed globally during that time.

Endocast

Endocast

An endocast is the internal cast of a hollow object, often referring to the cranial vault in the study of brain development in humans and other organisms. Endocasts can be artificially made for examining the properties of a hollow, inaccessible space, or they may occur naturally through fossilization.

Mazon Creek fossil beds

Mazon Creek fossil beds

The Mazon Creek fossil beds are a conservation lagerstätte found near Morris, in Grundy County, Illinois. The fossils are preserved in ironstone concretions, formed approximately 309 million years ago in the mid-Pennsylvanian epoch of the Carboniferous period. These concretions frequently preserve both hard and soft tissues of animal and plant materials, as well as many soft-bodied organisms that do not normally fossilize. The quality, quantity and diversity of fossils in the area, known since the mid-nineteenth century, make the Mazon Creek lagerstätte important to paleontologists, in attempting to reconstruct the paleoecology of the sites. The locality was declared a National Historic Landmark in 1997.

Jurassic

Jurassic

The Jurassic is a geologic period and stratigraphic system that spanned from the end of the Triassic Period 201.4 million years ago (Mya) to the beginning of the Cretaceous Period, approximately 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified.

Types

Examples of index fossils
Examples of index fossils

Index

Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages). They work on the premise that, although different sediments may look different depending on the conditions under which they were deposited, they may include the remains of the same species of fossil. The shorter the species' time range, the more precisely different sediments can be correlated, and so rapidly evolving species' fossils are particularly valuable. The best index fossils are common, easy to identify at species level and have a broad distribution—otherwise the likelihood of finding and recognizing one in the two sediments is poor.

Trace

Trace fossils consist mainly of tracks and burrows, but also include coprolites (fossil feces) and marks left by feeding.[30][31] Trace fossils are particularly significant because they represent a data source that is not limited to animals with easily fossilized hard parts, and they reflect animal behaviours. Many traces date from significantly earlier than the body fossils of animals that are thought to have been capable of making them.[32] Whilst exact assignment of trace fossils to their makers is generally impossible, traces may for example provide the earliest physical evidence of the appearance of moderately complex animals (comparable to earthworms).[31]

Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. They were first described by William Buckland in 1829. Prior to this they were known as "fossil fir cones" and "bezoar stones." They serve a valuable purpose in paleontology because they provide direct evidence of the predation and diet of extinct organisms.[33] Coprolites may range in size from a few millimetres to over 60 centimetres.

Transitional

A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group.[34] This is especially important where the descendant group is sharply differentiated by gross anatomy and mode of living from the ancestral group. Because of the incompleteness of the fossil record, there is usually no way to know exactly how close a transitional fossil is to the point of divergence. These fossils serve as a reminder that taxonomic divisions are human constructs that have been imposed in hindsight on a continuum of variation.

Microfossils

Microfossils about 1 mm
Microfossils about 1 mm

Microfossil is a descriptive term applied to fossilized plants and animals whose size is just at or below the level at which the fossil can be analyzed by the naked eye. A commonly applied cutoff point between "micro" and "macro" fossils is 1 mm. Microfossils may either be complete (or near-complete) organisms in themselves (such as the marine plankters foraminifera and coccolithophores) or component parts (such as small teeth or spores) of larger animals or plants. Microfossils are of critical importance as a reservoir of paleoclimate information, and are also commonly used by biostratigraphers to assist in the correlation of rock units.

Resin

The wasp Leptofoenus pittfieldae trapped in Dominican amber, from 20 to 16 million years ago. It is known only from this specimen.
The wasp Leptofoenus pittfieldae trapped in Dominican amber, from 20 to 16 million years ago. It is known only from this specimen.

Fossil resin (colloquially called amber) is a natural polymer found in many types of strata throughout the world, even the Arctic. The oldest fossil resin dates to the Triassic, though most dates to the Cenozoic. The excretion of the resin by certain plants is thought to be an evolutionary adaptation for protection from insects and to seal wounds. Fossil resin often contains other fossils called inclusions that were captured by the sticky resin. These include bacteria, fungi, other plants, and animals. Animal inclusions are usually small invertebrates, predominantly arthropods such as insects and spiders, and only extremely rarely a vertebrate such as a small lizard. Preservation of inclusions can be exquisite, including small fragments of DNA.

Derived, or reworked

Eroded Jurassic plesiosaur vertebral centrum found in the Lower Cretaceous Faringdon Sponge Gravels in Faringdon, England. An example of a remanié fossil.
Eroded Jurassic plesiosaur vertebral centrum found in the Lower Cretaceous Faringdon Sponge Gravels in Faringdon, England. An example of a remanié fossil.

A derived, reworked or remanié fossil is a fossil found in rock that accumulated significantly later than when the fossilized animal or plant died.[35] Reworked fossils are created by erosion exhuming (freeing) fossils from the rock formation in which they were originally deposited and their redeposition in a younger sedimentary deposit.

Wood

Petrified wood. The internal structure of the tree and bark are maintained in the permineralization process.Polished section of petrified wood showing annual rings
Petrified wood. The internal structure of the tree and bark are maintained in the permineralization process.
Petrified wood. The internal structure of the tree and bark are maintained in the permineralization process.Polished section of petrified wood showing annual rings
Polished section of petrified wood showing annual rings

Fossil wood is wood that is preserved in the fossil record. Wood is usually the part of a plant that is best preserved (and most easily found). Fossil wood may or may not be petrified. The fossil wood may be the only part of the plant that has been preserved;[36] therefore such wood may get a special kind of botanical name. This will usually include "xylon" and a term indicating its presumed affinity, such as Araucarioxylon (wood of Araucaria or some related genus), Palmoxylon (wood of an indeterminate palm), or Castanoxylon (wood of an indeterminate chinkapin).[37]

Subfossil

A subfossil dodo skeleton
A subfossil dodo skeleton

The term subfossil can be used to refer to remains, such as bones, nests, or fecal deposits, whose fossilization process is not complete, either because the length of time since the animal involved was living is too short (less than 10,000 years) or because the conditions in which the remains were buried were not optimal for fossilization.[38] Subfossils are often found in caves or other shelters where they can be preserved for thousands of years.[39] The main importance of subfossil vs. fossil 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 much 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, and small subfossils can also be ingested by living organisms. Subfossil remains that date from the Mesozoic are exceptionally rare, are usually in an advanced state of decay, and are consequently much disputed.[40] The vast bulk of subfossil material comes from Quaternary sediments, including many subfossilized chironomid head capsules, ostracod carapaces, diatoms, and foraminifera.

Subfossil Theba geminata
Subfossil Theba geminata

For remains such as molluscan seashells, which frequently do not change their chemical composition over geological time, and may occasionally even retain such features as the original color markings for millions of years, the label 'subfossil' is applied to shells that are understood to be thousands of years old, but are of Holocene age, and therefore are not old enough to be from the Pleistocene epoch.

Chemical fossils

Chemical fossils, or chemofossils, are chemicals found in rocks and fossil fuels (petroleum, coal, and natural gas) that provide an organic signature for ancient life. Molecular fossils and isotope ratios represent two types of chemical fossils.[41] The oldest traces of life on Earth are fossils of this type, including carbon isotope anomalies found in zircons that imply the existence of life as early as 4.1 billion years ago.[6][7]

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Sediment

Sediment

Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone through lithification.

Species

Species

In biology, a species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour, or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined.

Trace fossil

Trace fossil

A trace fossil, also known as an ichnofossil, is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or mineralization. The study of such trace fossils is ichnology and is the work of ichnologists.

Coprolite

Coprolite

A coprolite is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour rather than morphology. The name is derived from the Greek words κόπρος and λίθος. They were first described by William Buckland in 1829. Before this, they were known as "fossil fir cones" and "bezoar stones". They serve a valuable purpose in paleontology because they provide direct evidence of the predation and diet of extinct organisms. Coprolites may range in size from a few millimetres to over 60 centimetres.

Feces

Feces

Feces, known colloquially and in slang as poo, caca, scat and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relatively small amount of metabolic waste products such as bacterially altered bilirubin, and dead epithelial cells from the lining of the gut.

Earthworm

Earthworm

An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. They occur worldwide where soil, water, and temperature allow.

Bezoar

Bezoar

A bezoar is a mass often found trapped in the gastrointestinal system, though it can occur in other locations. A pseudobezoar is an indigestible object introduced intentionally into the digestive system.

Cambrian

Cambrian

The Cambrian Period is the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period 485.4 mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biology surpasses that of some later periods.

Rusophycus

Rusophycus

Rusophycus is a trace fossil ichnogenus allied to Cruziana. Rusophycus is the resting trace, recording the outline of the tracemaker; Cruziana is made when the organism moved. The sculpture of Rusophycus may reveal the approximate number of legs that the tracemaker had, although striations (scratchmarks) from a single leg may overlap or be repeated.

Saskatchewan

Saskatchewan

Saskatchewan is a province in Western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North Dakota. Saskatchewan and Alberta are the only landlocked provinces of Canada. In 2022, Saskatchewan's population was estimated at 1,214,618. Nearly 10% of Saskatchewan’s total area of 651,900 square kilometres (251,700 sq mi) is fresh water, mostly rivers, reservoirs and lakes.

Climactichnites

Climactichnites

Climactichnites is an enigmatic, Cambrian fossil formed on or within sandy tidal flats around 510 million years ago. It has been interpreted in many different ways in the past, but is now thought to be a trace fossil of a slug-like organism that moved by crawling to on-shore surfaces, or near-shore, or burrowing into the sediment.

Transitional fossil

Transitional fossil

A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group. This is especially important where the descendant group is sharply differentiated by gross anatomy and mode of living from the ancestral group. These fossils serve as a reminder that taxonomic divisions are human constructs that have been imposed in hindsight on a continuum of variation. Because of the incompleteness of the fossil record, there is usually no way to know exactly how close a transitional fossil is to the point of divergence. Therefore, it cannot be assumed that transitional fossils are direct ancestors of more recent groups, though they are frequently used as models for such ancestors.

Dating

Estimating dates

Paleontology seeks to map out how life evolved across geologic time. A substantial hurdle is the difficulty of working out fossil ages. Beds that preserve fossils typically lack the radioactive elements needed for radiometric dating. This technique is our only means of giving rocks greater than about 50 million years old an absolute age, and can be accurate to within 0.5% or better.[42] Although radiometric dating requires careful laboratory work, its basic principle is simple: the rates at which various radioactive elements decay are known, and so the ratio of the radioactive element to its decay products shows how long ago the radioactive element was incorporated into the rock. Radioactive elements are common only in rocks with a volcanic origin, and so the only fossil-bearing rocks that can be dated radiometrically are volcanic ash layers, which may provide termini for the intervening sediments.[42]

Stratigraphy

Consequently, palaeontologists rely on stratigraphy to date fossils. Stratigraphy is the science of deciphering the "layer-cake" that is the sedimentary record.[43] Rocks normally form relatively horizontal layers, with each layer younger than the one underneath it. If a fossil is found between two layers whose ages are known, the fossil's age is claimed to lie between the two known ages.[44] Because rock sequences are not continuous, but may be broken up by faults or periods of erosion, it is very difficult to match up rock beds that are not directly adjacent. However, fossils of species that survived for a relatively short time can be used to match isolated rocks: this technique is called biostratigraphy. For instance, the conodont Eoplacognathus pseudoplanus has a short range in the Middle Ordovician period.[45] If rocks of unknown age have traces of E. pseudoplanus, they have a mid-Ordovician age. Such index fossils must be distinctive, be globally distributed and occupy a short time range to be useful. Misleading results are produced if the index fossils are incorrectly dated.[46] Stratigraphy and biostratigraphy can in general provide only relative dating (A was before B), which is often sufficient for studying evolution. However, this is difficult for some time periods, because of the problems involved in matching rocks of the same age across continents.[46] Family-tree relationships also help to narrow down the date when lineages first appeared. For instance, if fossils of B or C date to X million years ago and the calculated "family tree" says A was an ancestor of B and C, then A must have evolved earlier.

It is also possible to estimate how long ago two living clades diverged, in other words approximately how long ago their last common ancestor must have lived, by assuming that DNA mutations accumulate at a constant rate. These "molecular clocks", however, are fallible, and provide only approximate timing: for example, they are not sufficiently precise and reliable for estimating when the groups that feature in the Cambrian explosion first evolved,[47] and estimates produced by different techniques may vary by a factor of two.[48]

Limitations

Some of the most remarkable gaps in the fossil record (as of October 2013) show slanting toward organisms with hard parts.
Some of the most remarkable gaps in the fossil record (as of October 2013) show slanting toward organisms with hard parts.

Organisms are only rarely preserved as fossils in the best of circumstances, and only a fraction of such fossils have been discovered. This is illustrated by the fact that the number of species known through the fossil record is less than 5% of the number of known living species, suggesting that the number of species known through fossils must be far less than 1% of all the species that have ever lived.[49] Because of the specialized and rare circumstances required for a biological structure to fossilize, only a small percentage of life-forms can be expected to be represented in discoveries, and each discovery represents only a snapshot of the process of evolution. The transition itself can only be illustrated and corroborated by transitional fossils, which will never demonstrate an exact half-way point.[50]

The fossil record is strongly biased toward organisms with hard-parts, leaving most groups of soft-bodied organisms with little to no role.[49] It is replete with the mollusks, the vertebrates, the echinoderms, the brachiopods and some groups of arthropods.[51]

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Geochronology

Geochronology

Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves. Absolute geochronology can be accomplished through radioactive isotopes, whereas relative geochronology is provided by tools such as paleomagnetism and stable isotope ratios. By combining multiple geochronological indicators the precision of the recovered age can be improved.

Radiometric dating

Radiometric dating

Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay. The use of radiometric dating was first published in 1907 by Bertram Boltwood and is now the principal source of information about the absolute age of rocks and other geological features, including the age of fossilized life forms or the age of Earth itself, and can also be used to date a wide range of natural and man-made materials.

Radioactive decay

Radioactive decay

Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha decay, beta decay, and gamma decay, all of which involve emitting one or more particles. The weak force is the mechanism that is responsible for beta decay, while the other two are governed by the electromagnetism and nuclear force. A fourth type of common decay is electron capture, in which an unstable nucleus captures an inner electron from one of the electron shells. The loss of that electron from the shell results in a cascade of electrons dropping down to that lower shell resulting in emission of discrete X-rays from the transitions. A common example is iodine-125 commonly used in medical settings.

Fault (geology)

Fault (geology)

In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep.

Erosion

Erosion

Erosion is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres.

Continent

Continent

A continent is any of several large geographical regions. Continents are generally identified by convention rather than any strict criteria. A continent could be a single landmass or a part of a very large landmass, as in the case of Asia or Europe. Due to this, the number of continents varies; up to seven or as few as four geographical regions are commonly regarded as continents. Most English-speaking countries recognize seven regions as continents. In order from largest to smallest in area, these seven regions are Asia, Africa, North America, South America, Antarctica, Europe, and Australia. Different variations with fewer continents merge some of these regions, examples of this are merging North America and South America into America, Asia and Europe into Eurasia, and Africa, Asia, and Europe into Afro-Eurasia.

Mutation

Mutation

In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA, which then may undergo error-prone repair, cause an error during other forms of repair, or cause an error during replication. Mutations may also result from insertion or deletion of segments of DNA due to mobile genetic elements.

Molecular clock

Molecular clock

The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleotide sequences for DNA, RNA, or amino acid sequences for proteins. The benchmarks for determining the mutation rate are often fossil or archaeological dates. The molecular clock was first tested in 1962 on the hemoglobin protein variants of various animals, and is commonly used in molecular evolution to estimate times of speciation or radiation. It is sometimes called a gene clock or an evolutionary clock.

Cambrian explosion

Cambrian explosion

The Cambrian explosion, Cambrian radiation, Cambrian diversification, or the Biological Big Bang refers to an interval of time approximately 538.8 million years ago in the Cambrian Period when practically all major animal phyla started appearing in the fossil record. It lasted for about 13 – 25 million years and resulted in the divergence of most modern metazoan phyla. The event was accompanied by major diversification in other groups of organisms as well.

Ghost lineage

Ghost lineage

A ghost lineage is a hypothesized ancestor in a species lineage that has left no fossil evidence yet can be inferred to exist because of gaps in the fossil record or genomic evidence. The process of determining a ghost lineage relies on fossilized evidence before and after the hypothetical existence of the lineage and extrapolating relationships between organisms based on phylogenetic analysis. Ghost lineages assume unseen diversity in the fossil record and serve as predictions for what the fossil record could eventually yield; these hypotheses can be tested by unearthing new fossils or running phylogenetic analyses.

Biostratigraphy

Biostratigraphy

Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. The primary objective of biostratigraphy is correlation, demonstrating that a particular horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossils are used to help identify biozones, as they make up the basic biostratigraphy units, and define geological time periods based upon the fossil species found within each section.

Echinoderm

Echinoderm

An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian.

Sites

Lagerstätten

Fossil sites with exceptional preservation—sometimes including preserved soft tissues—are known as Lagerstätten—German for "storage places". These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus slowing decomposition. Lagerstätten span geological time from the Cambrian period to the present. Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan shales and Burgess Shale, the Devonian Hunsrück Slates, the Jurassic Solnhofen limestone, and the Carboniferous Mazon Creek localities.

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Lagerstätte

Lagerstätte

A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying the decomposition of both gross and fine biological features until long after a durable impression was created in the surrounding matrix. Lagerstätten span geological time from the Neoproterozoic era to the present. Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan shales and Burgess Shale, the Silurian Waukesha Biota, the Devonian Hunsrück Slates and Gogo Formation, the Carboniferous Mazon Creek, the Jurassic Posidonia Shale and Solnhofen Limestone, the Cretaceous Yixian, Santana, and Agua Nueva formations, the Eocene Green River Formation, the Miocene Foulden Maar and Ashfall Fossil Beds, the Pliocene Gray Fossil Site, the Pleistocene Naracoorte Caves, the La Brea Tar Pits, and the Tanis Fossil Site.

List of fossil sites

List of fossil sites

This list of fossil sites is a worldwide list of localities known well for the presence of fossils. Some entries in this list are notable for a single, unique find, while others are notable for the large number of fossils found there. Many of the entries in this list are considered Lagerstätten. Lagerstätten are indicated by a note in the noteworthiness column.

Hypoxia (environmental)

Hypoxia (environmental)

Hypoxia refers to low oxygen conditions. Normally, 20.9% of the gas in the atmosphere is oxygen. The partial pressure of oxygen in the atmosphere is 20.9% of the total barometric pressure. In water, oxygen levels are much lower, approximately 7 ppm or 0.0007% in good quality water, and fluctuate locally depending on the presence of photosynthetic organisms and relative distance to the surface.

Cambrian

Cambrian

The Cambrian Period is the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period 485.4 mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biology surpasses that of some later periods.

Holocene

Holocene

The Holocene is the current geological epoch. It began approximately 11,650 cal years Before Present, after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.

Burgess Shale

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 old, it is one of the earliest fossil beds containing soft-part imprints.

Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, 419.2 million years ago (Mya), to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, England, where rocks from this period were first studied.

Jurassic

Jurassic

The Jurassic is a geologic period and stratigraphic system that spanned from the end of the Triassic Period 201.4 million years ago (Mya) to the beginning of the Cretaceous Period, approximately 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified.

Carboniferous

Carboniferous

The Carboniferous is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 million years ago (Mya), to the beginning of the Permian Period, 298.9 million years ago. The name Carboniferous means "coal-bearing", from the Latin carbō ("coal") and ferō, and refers to the many coal beds formed globally during that time.

Stromatolites

Lower Proterozoic stromatolites from Bolivia, South America
Lower Proterozoic stromatolites from Bolivia, South America

Stromatolites are layered accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria.[52] Stromatolites provide some of the most ancient fossil records of life on Earth, dating back more than 3.5 billion years ago.[53]

Stromatolites were much more abundant in Precambrian times. While older, Archean fossil remains are presumed to be colonies of cyanobacteria, younger (that is, Proterozoic) fossils may be primordial forms of the eukaryote chlorophytes (that is, green algae). One genus of stromatolite very common in the geologic record is Collenia. The earliest stromatolite of confirmed microbial origin dates to 2.724 billion years ago.[54]

A 2009 discovery provides strong evidence of microbial stromatolites extending as far back as 3.45 billion years ago.[55][56]

Stromatolites are a major constituent of the fossil record for life's first 3.5 billion years, peaking about 1.25 billion years ago.[55] They subsequently declined in abundance and diversity,[57] which by the start of the Cambrian had fallen to 20% of their peak. The most widely supported explanation is that stromatolite builders fell victims to grazing creatures (the Cambrian substrate revolution), implying that sufficiently complex organisms were common over 1 billion years ago.[58][59][60]

The connection between grazer and stromatolite abundance is well documented in the younger Ordovician evolutionary radiation; stromatolite abundance also increased after the end-Ordovician and end-Permian extinctions decimated marine animals, falling back to earlier levels as marine animals recovered.[61] Fluctuations in metazoan population and diversity may not have been the only factor in the reduction in stromatolite abundance. Factors such as the chemistry of the environment may have been responsible for changes.[62]

While prokaryotic cyanobacteria themselves reproduce asexually through cell division, they were instrumental in priming the environment for the evolutionary development of more complex eukaryotic organisms. Cyanobacteria (as well as extremophile Gammaproteobacteria) are thought to be largely responsible for increasing the amount of oxygen in the primeval earth's atmosphere through their continuing photosynthesis. Cyanobacteria use water, carbon dioxide and sunlight to create their food. A layer of mucus often forms over mats of cyanobacterial cells. In modern microbial mats, debris from the surrounding habitat can become trapped within the mucus, which can be cemented by the calcium carbonate to grow thin laminations of limestone. These laminations can accrete over time, resulting in the banded pattern common to stromatolites. The domal morphology of biological stromatolites is the result of the vertical growth necessary for the continued infiltration of sunlight to the organisms for photosynthesis. Layered spherical growth structures termed oncolites are similar to stromatolites and are also known from the fossil record. Thrombolites are poorly laminated or non-laminated clotted structures formed by cyanobacteria common in the fossil record and in modern sediments.[54]

The Zebra River Canyon area of the Kubis platform in the deeply dissected Zaris Mountains of southwestern Namibia provides an extremely well exposed example of the thrombolite-stromatolite-metazoan reefs that developed during the Proterozoic period, the stromatolites here being better developed in updip locations under conditions of higher current velocities and greater sediment influx.[63]

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Bolivia

Bolivia

Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in western-central South America. It is bordered by Brazil to the north and east, Paraguay to the southeast, Argentina to the south, Chile to the southwest and Peru to the west. The seat of government and executive capital is La Paz, while the constitutional capital is Sucre. The largest city and principal industrial center is Santa Cruz de la Sierra, located on the Llanos Orientales, a mostly flat region in the east of the country.

Accretion (geology)

Accretion (geology)

Accretion, in geology, is a process by which material is added to a tectonic plate at a subduction zone, frequently on the edge of existing continental landmasses. The added material may be sediment, volcanic arcs, seamounts, oceanic crust or other igneous features.

Biofilm

Biofilm

A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPSs). The cells within the biofilm produce the EPS components, which are typically a polymeric conglomeration of extracellular polysaccharides, proteins, lipids and DNA. Because they have three-dimensional structure and represent a community lifestyle for microorganisms, they have been metaphorically described as "cities for microbes".

Cyanobacteria

Cyanobacteria

Cyanobacteria, also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name cyanobacteria refers to their color, which similarly forms the basis of cyanobacteria's common name, blue-green algae, although they are not usually scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment. Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria.

Archean

Archean

The Archean Eon, in older sources sometimes called the Archaeozoic, is the second of four geologic eons of Earth's history and by definition representing the time from 4 to 2.5 billion years ago. The Archean was preceded by the Hadean Eon and followed by the Proterozoic.

Colony (biology)

Colony (biology)

In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger prey.

Chlorophyta

Chlorophyta

Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophytes. The name is used in two very different senses, so care is needed to determine the use by a particular author. In older classification systems, it refers to a highly paraphyletic group of all the green algae within the green plants (Viridiplantae) and thus includes about 7,000 species of mostly aquatic photosynthetic eukaryotic organisms. In newer classifications, it refers to the sister clade of the streptophytes/charophytes. The clade Streptophyta consists of the Charophyta in which the Embryophyta emerged. In this latter sense the Chlorophyta includes only about 4,300 species. About 90% of all known species live in freshwater. Like the land plants, green algae contain chlorophyll a and chlorophyll b and store food as starch in their plastids.

Green algae

Green algae

The green algae are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as sister of the Zygnematophyceae. Since the realization that the Embryophytes emerged within the green algae, some authors are starting to include them. The completed clade that includes both green algae and embryophytes is monophyletic and is referred to as the clade Viridiplantae and as the kingdom Plantae. The green algae include unicellular and colonial flagellates, most with two flagella per cell, as well as various colonial, coccoid and filamentous forms, and macroscopic, multicellular seaweeds. There are about 22,000 species of green algae. Many species live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds.

Genus

Genus

Genus is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.E.g. Panthera leo (lion) and Panthera onca (jaguar) are two species within the genus Panthera. Panthera is a genus within the family Felidae.

Geologic time scale

Geologic time scale

The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy and geochronology. It is used primarily by Earth scientists to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardized international units of geologic time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precisely define global chronostratigraphic units of the International Chronostratigraphic Chart (ICC) that are used to define divisions of geologic time. The chronostratigraphic divisions are in turn used to define geochronologic units.

Collenia

Collenia

Collenia is genus of fossil cyanobacteria that form a particular type of stromatolites.

Cambrian substrate revolution

Cambrian substrate revolution

The "Cambrian substrate revolution" or "Agronomic revolution", evidenced in trace fossils, is a sudden diversification of animal burrowing during the early Cambrian period.

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.[64]

On 24 January 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.[65][66][67][68] The search for evidence of habitability, taphonomy (related to fossils), and organic carbon on the planet Mars is now a primary NASA objective.[65][66]

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Biomineralization

Biomineralization

Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often to harden or stiffen existing tissues. Such tissues are called mineralized tissues. It is an extremely widespread phenomenon; all six taxonomic kingdoms contain members that are able to form minerals, and over 60 different minerals have been identified in organisms. Examples include silicates in algae and diatoms, carbonates in invertebrates, and calcium phosphates and carbonates in vertebrates. These minerals often form structural features such as sea shells and the bone in mammals and birds.

Extraterrestrial life

Extraterrestrial life

Extraterrestrial life, colloquially referred to as alien life, is life that may occur outside of Earth and which did not originate on Earth. No extraterrestrial life has yet been conclusively detected, although efforts are underway. Such life might range from simple forms like prokaryotes to intelligent beings, possibly bringing forth civilizations that might be far more advanced than humankind. The Drake equation speculates about the existence of sapient life elsewhere in the universe. The science of extraterrestrial life is known as astrobiology.

Mars

Mars

Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, larger only than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmosphere and has a crust primarily composed of elements similar to Earth's crust, as well as a core made of iron and nickel. Mars has surface features such as impact craters, valleys, dunes, and polar ice caps. Mars has two small, irregularly shaped moons, Phobos and Deimos.

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 or chemical structures and its use of free energy and the production of biomass and wastes. A biosignature can provide evidence for living organisms outside the Earth and can be directly or indirectly detected by searching for their unique byproducts.

Biotic material

Biotic material

Biotic material or biological derived material is any material that originates from living organisms. Most such materials contain carbon and are capable of decay.

Curiosity (rover)

Curiosity (rover)

Curiosity is a car-sized Mars rover designed to explore the Gale crater on Mars as part of NASA's Mars Science Laboratory (MSL) mission. Curiosity was launched from Cape Canaveral (CCAFS) on November 26, 2011, at 15:02:00 UTC and landed on Aeolis Palus inside Gale crater on Mars on August 6, 2012, 05:17:57 UTC. The Bradbury Landing site was less than 2.4 km (1.5 mi) from the center of the rover's touchdown target after a 560 million km (350 million mi) journey.

Mars rover

Mars rover

A Mars rover is a motor vehicle designed to travel on the surface of Mars. 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. They serve a different purpose than orbital spacecraft like Mars Reconnaissance Orbiter. A more recent development is the Mars helicopter.

Biosphere

Biosphere

The biosphere, also known as the ecosphere, is the worldwide sum of all ecosystems. It can also be termed the zone of life on Earth. The biosphere is virtually a closed system with regard to matter, with minimal inputs and outputs. Regarding energy, it is an open system, with photosynthesis capturing solar energy at a rate of around 130 terawatts per year. By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning with a process of biopoiesis or biogenesis, at least some 3.5 billion years ago.

Autotroph

Autotroph

An autotroph is an organism that produces complex organic compounds using carbon from simple substances such as carbon dioxide, generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They convert an abiotic source of energy into energy stored in organic compounds, which can be used by other organisms. Autotrophs do not need a living source of carbon or energy and are the producers in a food chain, such as plants on land or algae in water. Autotrophs can reduce carbon dioxide to make organic compounds for biosynthesis and as stored chemical fuel. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide.

Chemotroph

Chemotroph

A chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototrophs, which use photons. Chemotrophs can be either autotrophic or heterotrophic. Chemotrophs can be found in areas where electron donors are present in high concentration, for instance around hydrothermal vents.

Lacustrine plain

Lacustrine plain

A lacustrine plain or lake plain is a plain formed due to the past existence of a lake and its accompanying sediment accumulation. Lacustrine plains can be formed through one of three major mechanisms: glacial drainage, differential uplift, and inland lake creation and drainage. Lake plains can have various uses depending on where and how they form.

Lake

Lake

A lake is a naturally occurring, relatively large body of water localized in a basin completely surrounded by dry land, with much slower-moving flow than any inflow or outflow streams that serve to feed or drain it. Lakes lie completely on land and are separate from the ocean, although, like the much larger oceans, they form part of the Earth's water cycle by serving as large standing pools of storage water. Most lakes are freshwater, but some are salt lakes with salinities even higher than that of seawater.

Pseudofossils

An example of a pseudofossil: Manganese dendrites on a limestone bedding plane from Solnhofen, Germany; scale in mm
An example of a pseudofossil: Manganese dendrites on a limestone bedding plane from Solnhofen, Germany; scale in mm

Pseudofossils are visual patterns in rocks that are produced by geologic processes rather than biologic processes. They can easily be mistaken for real fossils. Some pseudofossils, such as geological dendrite crystals, are formed by naturally occurring fissures in the rock that get filled up by percolating minerals. Other types of pseudofossils are kidney ore (round shapes in iron ore) and moss agates, which look like moss or plant leaves. Concretions, spherical or ovoid-shaped nodules found in some sedimentary strata, were once thought to be dinosaur eggs, and are often mistaken for fossils as well.

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Solnhofen

Solnhofen

Solnhofen is a municipality in the district of Weißenburg-Gunzenhausen in the region of Middle Franconia in the Land of Bavaria in Germany. It is in the Altmühl valley.

Dendrite (crystal)

Dendrite (crystal)

A crystal dendrite is a crystal that develops with a typical multi-branching form. The name comes from the Greek word dendron (δενδρον) which means "tree", since the crystal's structure resembles that of a tree. These crystals can be synthesised by using a supercooled pure liquid, however they are also quite common in nature. The most common crystals in nature exhibit dendritic growth are snowflakes and frost on windows, but many minerals and metals can also be found in dendritic structures.

Moss agate

Moss agate

Moss agate is a semi-precious gemstone formed from silicon dioxide. It is a form of chalcedony which includes minerals of a green color embedded in the stone, forming filaments and other patterns suggestive of moss. The field is a clear or milky-white quartz, and the included minerals are mainly oxides of manganese or iron. It is not a true form of agate, because it does not have concentric banding.

Concretion

Concretion

A concretion is a hard, compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin concretio "(act of) compacting, condensing, congealing, uniting", itself from con meaning 'together' and crescere meaning "to grow". Concretions form within layers of sedimentary strata that have already been deposited. They usually form early in the burial history of the sediment, before the rest of the sediment is hardened into rock. This concretionary cement often makes the concretion harder and more resistant to weathering than the host stratum.

Dinosaur

Dinosaur

Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 245 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds.

History of the study of fossils

Gathering fossils dates at least to the beginning of recorded history. The fossils themselves are referred to as the fossil record. The fossil record was one of the early sources of data underlying the study of evolution and continues to be relevant to the history of life on Earth. Paleontologists examine the fossil record to understand the process of evolution and the way particular species have evolved.

Ancient civilizations

Fossils have been visible and common throughout most of natural history, and so documented human interaction with them goes back as far as recorded history, or earlier.

There are many examples of paleolithic stone knives in Europe, with fossil echinoderms set precisely at the hand grip, going all the way back to Homo heidelbergensis and Neanderthals.[69] These ancient peoples also drilled holes through the center of those round fossil shells, apparently using them as beads for necklaces.

The ancient Egyptians gathered fossils of species that resembled the bones of modern species they worshipped. The god Set was associated with the hippopotamus, therefore fossilized bones of hippo-like species were kept in that deity's temples.[70] Five-rayed fossil sea urchin shells were associated with the deity Sopdu, the Morning Star, equivalent of Venus in Roman mythology.[69]

Ceratopsian skulls are common in the Dzungarian Gate mountain pass in Asia, an area once famous for gold mines, as well as its endlessly cold winds. This has been attributed to legends of both gryphons and the land of Hyperborea.
Ceratopsian skulls are common in the Dzungarian Gate mountain pass in Asia, an area once famous for gold mines, as well as its endlessly cold winds. This has been attributed to legends of both gryphons and the land of Hyperborea.

Fossils appear to have directly contributed to the mythology of many civilizations, including the ancient Greeks. Classical Greek historian Herodotos wrote of an area near Hyperborea where gryphons protected golden treasure. There was indeed gold mining in that approximate region, where beaked Protoceratops skulls were common as fossils.

A later Greek scholar, Aristotle, eventually realized that fossil seashells from rocks were similar to those found on the beach, indicating the fossils were once living animals. He had previously explained them in terms of vaporous exhalations,[71] which Persian polymath Avicenna modified into the theory of petrifying fluids (succus lapidificatus). Recognition of fossil seashells as originating in the sea was built upon in the 14th century by Albert of Saxony, and accepted in some form by most naturalists by the 16th century.[72]

Roman naturalist Pliny the Elder wrote of "tongue stones", which he called glossopetra. These were fossil shark teeth, thought by some classical cultures to look like the tongues of people or snakes.[73] He also wrote about the horns of Ammon, which are fossil ammonites, from whence the group of shelled octopus-cousins ultimately draws its modern name. Pliny also makes one of the earlier known references to toadstones, thought until the 18th century to be a magical cure for poison originating in the heads of toads, but which are fossil teeth from Lepidotes, a Cretaceous ray-finned fish.[74]

The Plains tribes of North America are thought to have similarly associated fossils, such as the many intact pterosaur fossils naturally exposed in the region, with their own mythology of the thunderbird.[75]

There is no such direct mythological connection known from prehistoric Africa, but there is considerable evidence of tribes there excavating and moving fossils to ceremonial sites, apparently treating them with some reverence.[76]

In Japan, fossil shark teeth were associated with the mythical tengu, thought to be the razor-sharp claws of the creature, documented some time after the 8th century AD.[73]

In medieval China, the fossil bones of ancient mammals including Homo erectus were often mistaken for "dragon bones" and used as medicine and aphrodisiacs. In addition, some of these fossil bones are collected as "art" by scholars, who left scripts on various artifacts, indicating the time they were added to a collection. One good example is the famous scholar Huang Tingjian of the Song Dynasty during the 11th century, who kept a specific seashell fossil with his own poem engraved on it.[77] In his Dream Pool Essays published in 1088, Song dynasty Chinese scholar-official Shen Kuo hypothesized that marine fossils found in a geological stratum of mountains located hundreds of miles from the Pacific Ocean was evidence that a prehistoric seashore had once existed there and shifted over centuries of time.[78][79] His observation of petrified bamboos in the dry northern climate zone of what is now Yan'an, Shaanxi province, China, led him to advance early ideas of gradual climate change due to bamboo naturally growing in wetter climate areas.[79][80][81]

In medieval Christendom, fossilized sea creatures on mountainsides were seen as proof of the biblical deluge of Noah's Ark. After observing the existence of seashells in mountains, the ancient Greek philosopher Xenophanes (c. 570 – 478 BC) speculated that the world was once inundated in a great flood that buried living creatures in drying mud.[82][83]

In 1027, the Persian Avicenna explained fossils' stoniness in The Book of Healing:

If what is said concerning the petrifaction of animals and plants is true, the cause of this (phenomenon) is a powerful mineralizing and petrifying virtue which arises in certain stony spots, or emanates suddenly from the earth during earthquake and subsidences, and petrifies whatever comes into contact with it. As a matter of fact, the petrifaction of the bodies of plants and animals is not more extraordinary than the transformation of waters.[84]

From the 13th century to the present day, scholars pointed out that the fossil skulls of Deinotherium giganteum, found in Crete and Greece, might have been interpreted as being the skulls of the Cyclopes of Greek mythology, and are possibly the origin of that Greek myth.[85][86] Their skulls appear to have a single eye-hole in the front, just like their modern elephant cousins, though in fact it's actually the opening for their trunk.

Fossil shells from the cretaceous era sea urchin, Micraster, were used in medieval times as both shepherd's crowns to protect houses, and as painted fairy loaves by bakers to bring luck to their bread-making.
Fossil shells from the cretaceous era sea urchin, Micraster, were used in medieval times as both shepherd's crowns to protect houses, and as painted fairy loaves by bakers to bring luck to their bread-making.

In Norse mythology, echinoderm shells (the round five-part button left over from a sea urchin) were associated with the god Thor, not only being incorporated in thunderstones, representations of Thor's hammer and subsequent hammer-shaped crosses as Christianity was adopted, but also kept in houses to garner Thor's protection.[69]

These grew into the shepherd's crowns of English folklore, used for decoration and as good luck charms, placed by the doorway of homes and churches.[87] In Suffolk, a different species was used as a good-luck charm by bakers, who referred to them as fairy loaves, associating them with the similarly shaped loaves of bread they baked.[88][89]

Early modern explanations

More scientific views of fossils emerged during the Renaissance. Leonardo da Vinci concurred with Aristotle's view that fossils were the remains of ancient life.[90] For example, Leonardo noticed discrepancies with the biblical flood narrative as an explanation for fossil origins:

If the Deluge had carried the shells for distances of three and four hundred miles from the sea it would have carried them mixed with various other natural objects all heaped up together; but even at such distances from the sea we see the oysters all together and also the shellfish and the cuttlefish and all the other shells which congregate together, found all together dead; and the solitary shells are found apart from one another as we see them every day on the sea-shores.

And we find oysters together in very large families, among which some may be seen with their shells still joined together, indicating that they were left there by the sea and that they were still living when the strait of Gibraltar was cut through. In the mountains of Parma and Piacenza multitudes of shells and corals with holes may be seen still sticking to the rocks....[91]

Ichthyosaurus and Plesiosaurus from the 1834 Czech edition of Cuvier's Discours sur les revolutions de la surface du globe
Ichthyosaurus and Plesiosaurus from the 1834 Czech edition of Cuvier's Discours sur les revolutions de la surface du globe

In 1666, Nicholas Steno examined a shark, and made the association of its teeth with the "tongue stones" of ancient Greco-Roman mythology, concluding that those were not in fact the tongues of venomous snakes, but the teeth of some long-extinct species of shark.[73]

Robert Hooke (1635–1703) included micrographs of fossils in his Micrographia and was among the first to observe fossil forams. His observations on fossils, which he stated to be the petrified remains of creatures some of which no longer existed, were published posthumously in 1705.[92]

William Smith (1769–1839), an English canal engineer, observed that rocks of different ages (based on the law of superposition) preserved different assemblages of fossils, and that these assemblages succeeded one another in a regular and determinable order. He observed that rocks from distant locations could be correlated based on the fossils they contained. He termed this the principle of faunal succession. This principle became one of Darwin's chief pieces of evidence that biological evolution was real.

Georges Cuvier came to believe that most if not all the animal fossils he examined were remains of extinct species. This led Cuvier to become an active proponent of the geological school of thought called catastrophism. Near the end of his 1796 paper on living and fossil elephants he said:

All of these facts, consistent among themselves, and not opposed by any report, seem to me to prove the existence of a world previous to ours, destroyed by some kind of catastrophe.[93]

Interest in fossils, and geology more generally, expanded during the early nineteenth century. In Britain, Mary Anning's discoveries of fossils, including the first complete ichthyosaur and a complete plesiosaurus skeleton, sparked both public and scholarly interest.[94]

Linnaeus and Darwin

Early naturalists well understood the similarities and differences of living species leading Linnaeus to develop a hierarchical classification system still in use today. Darwin and his contemporaries first linked the hierarchical structure of the tree of life with the then very sparse fossil record. Darwin eloquently described a process of descent with modification, or evolution, whereby organisms either adapt to natural and changing environmental pressures, or they perish.

When Darwin wrote On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, the oldest animal fossils were those from the Cambrian Period, now known to be about 540 million years old. He worried about the absence of older fossils because of the implications on the validity of his theories, but he expressed hope that such fossils would be found, noting that: "only a small portion of the world is known with accuracy." Darwin also pondered the sudden appearance of many groups (i.e. phyla) in the oldest known Cambrian fossiliferous strata.[95]

After Darwin

Since Darwin's time, the fossil record has been extended to between 2.3 and 3.5 billion years.[96] Most of these Precambrian fossils are microscopic bacteria or microfossils. However, macroscopic fossils are now known from the late Proterozoic. The Ediacara biota (also called Vendian biota) dating from 575 million years ago collectively constitutes a richly diverse assembly of early multicellular eukaryotes.

The fossil record and faunal succession form the basis of the science of biostratigraphy or determining the age of rocks based on embedded fossils. For the first 150 years of geology, biostratigraphy and superposition were the only means for determining the relative age of rocks. The geologic time scale was developed based on the relative ages of rock strata as determined by the early paleontologists and stratigraphers.

Since the early years of the twentieth century, absolute dating methods, such as radiometric dating (including potassium/argon, argon/argon, uranium series, and, for very recent fossils, radiocarbon dating) have been used to verify the relative ages obtained by fossils and to provide absolute ages for many fossils. Radiometric dating has shown that the earliest known stromatolites are over 3.4 billion years old.

Modern era

The fossil record is life's evolutionary epic that unfolded over four billion years as environmental conditions and genetic potential interacted in accordance with natural selection.

The Virtual Fossil Museum[97]

Paleontology has joined with evolutionary biology to share the interdisciplinary task of outlining the tree of life, which inevitably leads backwards in time to Precambrian microscopic life when cell structure and functions evolved. Earth's deep time in the Proterozoic and deeper still in the Archean is only "recounted by microscopic fossils and subtle chemical signals."[98] Molecular biologists, using phylogenetics, can compare protein amino acid or nucleotide sequence homology (i.e., similarity) to evaluate taxonomy and evolutionary distances among organisms, with limited statistical confidence. The study of fossils, on the other hand, can more specifically pinpoint when and in what organism a mutation first appeared. Phylogenetics and paleontology work together in the clarification of science's still dim view of the appearance of life and its evolution.[99]

Phacopid trilobite Eldredgeops rana crassituberculata. The genus is named after Niles Eldredge.
Phacopid trilobite Eldredgeops rana crassituberculata. The genus is named after Niles Eldredge.
Crinoid columnals (Isocrinus nicoleti) from the Middle Jurassic Carmel Formation at Mount Carmel Junction, Utah
Crinoid columnals (Isocrinus nicoleti) from the Middle Jurassic Carmel Formation at Mount Carmel Junction, Utah

Niles Eldredge's study of the Phacops trilobite genus supported the hypothesis that modifications to the arrangement of the trilobite's eye lenses proceeded by fits and starts over millions of years during the Devonian.[100] Eldredge's interpretation of the Phacops fossil record was that the aftermaths of the lens changes, but not the rapidly occurring evolutionary process, were fossilized. This and other data led Stephen Jay Gould and Niles Eldredge to publish their seminal paper on punctuated equilibrium in 1971.

Synchrotron X-ray tomographic analysis of early Cambrian bilaterian embryonic microfossils yielded new insights of metazoan evolution at its earliest stages. The tomography technique provides previously unattainable three-dimensional resolution at the limits of fossilization. Fossils of two enigmatic bilaterians, the worm-like Markuelia and a putative, primitive protostome, Pseudooides, provide a peek at germ layer embryonic development. These 543-million-year-old embryos support the emergence of some aspects of arthropod development earlier than previously thought in the late Proterozoic. The preserved embryos from China and Siberia underwent rapid diagenetic phosphatization resulting in exquisite preservation, including cell structures. This research is a notable example of how knowledge encoded by the fossil record continues to contribute otherwise unattainable information on the emergence and development of life on Earth. For example, the research suggests Markuelia has closest affinity to priapulid worms, and is adjacent to the evolutionary branching of Priapulida, Nematoda and Arthropoda.[101]

Despite significant advances in uncovering and identifying paleontological specimens, it is generally accepted that the fossil record is vastly incomplete.[102][103] Approaches for measuring the completeness of the fossil record have been developed for numerous subsets of species, including those grouped taxonomically,[104][105] temporally,[106] environmentally/geographically,[107] or in sum.[108][109] This encompasses the subfield of taphonomy and the study of biases in the paleontological record.[110][111][112]

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History of paleontology

History of paleontology

The history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms. Since it is concerned with understanding living organisms of the past, paleontology can be considered to be a field of biology, but its historical development has been closely tied to geology and the effort to understand the history of Earth itself.

Evolution

Evolution

In biology, evolution is the change in heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation.

Paleolithic

Paleolithic

The Paleolithic or Palaeolithic, also called the Old Stone Age, is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehistoric technology. It extends from the earliest known use of stone tools by hominins, c. 3.3 million years ago, to the end of the Pleistocene, c. 11,650 cal BP.

Echinoderm

Echinoderm

An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian.

Homo heidelbergensis

Homo heidelbergensis

Homo heidelbergensis is an extinct species or subspecies of archaic human which existed during the Middle Pleistocene. It was subsumed as a subspecies of H. erectus in 1950 as H. e. heidelbergensis, but towards the end of the century, it was more widely classified as its own species. It is debated whether or not to constrain H. heidelbergensis to only Europe or to also include African and Asian specimens, and this is further confounded by the type specimen being a jawbone, because jawbones feature few diagnostic traits and are generally missing among Middle Pleistocene specimens. Thus, it is debated if some of these specimens could be split off into their own species or a subspecies of H. erectus. Because the classification is so disputed, the Middle Pleistocene is often called the "muddle in the middle."

Neanderthal

Neanderthal

Neanderthals, also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. The reasons for Neanderthal extinction are disputed. Theories for their extinction include demographic factors such as small population size and inbreeding; competitive replacement; interbreeding and assimilation with modern humans; climate change; disease; or a combination of these factors.

Set (deity)

Set (deity)

Set is a god of deserts, storms, disorder, violence, and foreigners in ancient Egyptian religion. In Ancient Greek, the god's name is given as Sēth (Σήθ). Set had a positive role where he accompanies Ra on his barque to repel Apep, the serpent of Chaos. Set had a vital role as a reconciled combatant. He was lord of the Red Land (desert), where he was the balance to Horus' role as lord of the Black Land.

Hippopotamus

Hippopotamus

The hippopotamus or hippo, further qualified as the common hippopotamus, Nile hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extant species in the family Hippopotamidae, the other being the pygmy hippopotamus. Its name comes from the ancient Greek for "river horse" (ἱπποπόταμος).

Sopdu

Sopdu

Sopdu was a god of the sky and of eastern border regions in the religion of Ancient Egypt. He was Khensit's husband.

Dzungarian Gate

Dzungarian Gate

The Dzungarian Gate is a geographically and historically significant mountain pass between China and Central Asia. It has been described as the "one and only gateway in the mountain-wall which stretches from Manchuria to Afghanistan, over a distance of three thousand miles [4,800 km]." Given its association with details in a story related by Herodotus, it has been linked to the location of legendary Hyperborea.

Hyperborea

Hyperborea

In Greek mythology, the Hyperboreans were a mythical people who lived in the far northern part of the known world. Their name appears to derive from the Greek ὑπέρ Βορέᾱ, "beyond Boreas", although some scholars prefer a derivation from ὑπερφέρω.

Protoceratops

Protoceratops

Protoceratops is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 75 to 71 million years ago. The genus Protoceratops includes two species: P. andrewsi and the larger P. hellenikorhinus. The former was described in 1923 with fossils from the Mongolian Djadokhta Formation, and the latter in 2001 with fossils from the Chinese Bayan Mandahu Formation. Protoceratops was initially believed to be an ancestor of ankylosaurians and larger ceratopsians, such as Triceratops and relatives, until the discoveries of other protoceratopsids. Populations of P. andrewsi may have evolved into Bagaceratops through anagenesis.

Art

According to one hypothesis, a Corinthian vase from the 6th century B.C. C. is the oldest artistic record of a vertebrate fossil, perhaps a Miocene giraffe combined with elements from other species.[113][114] However, a subsequent study using artificial intelligence and expert evaluations reject this idea, because mammals do not have the eye bones shown in the painted monster. Morphologically, the vase painting correspond to a carnivorous reptile of the Varanidae family that still lives in regions occupied by the ancient Greek.[115]

Trading and collecting

Fossil trading is the practice of buying and selling fossils. This is many times done illegally with artifacts stolen from research sites, costing many important scientific specimens each year.[116] The problem is quite pronounced in China, where many specimens have been stolen.[117]

Fossil collecting (sometimes, in a non-scientific sense, fossil hunting) is the collection of fossils for scientific study, hobby, or profit. Fossil collecting, as practiced by amateurs, is the predecessor of modern paleontology and many still collect fossils and study fossils as amateurs. Professionals and amateurs alike collect fossils for their scientific value.

As medicine

The use of fossils to address health issues is rooted in traditional medicine and include the use of fossils as talismans. The specific fossil to use to alleviate or cure an illness is often based on its resemblance to the symptoms or affected organ. The usefulness of fossils as medicine is almost entirely a placebo effect, though fossil material might conceivably have some antacid activity or supply some essential minerals.[118] The use of dinosaur bones as "dragon bones" has persisted in Traditional Chinese medicine into modern times, with mid-Cretaceous dinosaur bones being used for the purpose in Ruyang County during the early 21st century.[119]

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Traditional medicine

Traditional medicine

Traditional medicine comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the era of modern medicine. The World Health Organization (WHO) defines traditional medicine as "the sum total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement or treatment of physical and mental illness". Traditional medicine is often contrasted with scientific medicine.

Talisman

Talisman

A talisman is any object ascribed with religious or magical powers intended to protect, heal, or harm individuals for whom they are made. Talismans are often portable objects carried on someone in a variety of ways, but can also be installed permanently in architecture. Talismans are closely linked with amulets, fulfilling many of the same roles, but a key difference is in their form and materiality, with talismans often taking the form of objects which are inscribed with magic texts.

Antacid

Antacid

An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. Some antacids have been used in the treatment of constipation and diarrhea. Marketed antacids contain salts of aluminium, calcium, magnesium, or sodium. Some preparations contain a combination of two salts, such as magnesium carbonate and aluminium hydroxide.

Traditional Chinese medicine

Traditional Chinese medicine

Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of action.

Ruyang County

Ruyang County

Ruyang County is a county in the west of Henan province, China, under the jurisdiction of the prefecture-level city of Luoyang.

Gallery

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Dhankar Gompa

Dhankar Gompa

Dhankar Gompa is a village and also a Gompa, a Buddhist temple in the district of Lahaul and Spiti in India. It is situated at an elevation of 3,894 metres in the Spiti Valley above Dhankar Village, between the towns of Kaza and Tabo. The complex is built on a 1000-foot (300-metre) high spur overlooking the confluence of the Spiti and Pin Rivers - one of the world's most spectacular settings for a gompa. Dhang or dang means cliff, and kar or khar means fort. Hence Dhangkar means fort on a cliff.

Eocene

Eocene

The Eocene Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name Eocene comes from the Ancient Greek ἠώς and καινός and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.

Green River Formation

Green River Formation

The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in the dry season. Each pair of layers is called a varve and represents one year. The sediments of the Green River Formation present a continuous record of six million years. The mean thickness of a varve here is 0.18 mm, with a minimum thickness of 0.014 mm and maximum of 9.8 mm.

Asaphus kowalewskii

Asaphus kowalewskii

Asaphus kowalewskii is one of the 35 species of trilobites of the genus Asaphus. Fossils of this species are popular among collectors because of their prominent stalked eyes, many an inch or more in length.

Megalodon

Megalodon

Megalodon, meaning "big tooth", is an extinct species of mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. It was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark. However, it is now classified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous.

Carcharodontosaurus

Carcharodontosaurus

Carcharodontosaurus is a genus of large carcharodontosaurid theropod dinosaur that existed during the Cenomanian age of the Late Cretaceous in Northern Africa. The genus Carcharodontosaurus is named after the shark genus Carcharodon, itself composed of the Greek karchar[os] and odōn, and the suffix -saurus ("lizard"). It is currently known to have two species: C. saharicus and C. iguidensis.

Cretaceous

Cretaceous

The Cretaceous is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation Kreide.

Petrified Forest National Park

Petrified Forest National Park

Petrified Forest National Park is an American national park in Navajo and Apache counties in northeastern Arizona. Named for its large deposits of petrified wood, the park covers about 346 square miles, encompassing semi-desert shrub steppe as well as highly eroded and colorful badlands. The park's headquarters is about 26 miles (42 km) east of Holbrook along Interstate 40 (I-40), which parallels the BNSF Railway's Southern Transcon, the Puerco River, and historic U.S. Route 66, all crossing the park roughly east–west. The site, the northern part of which extends into the Painted Desert, was declared a national monument in 1906 and a national park in 1962. The park received 644,922 recreational visitors in 2018.

Conifer cone

Conifer cone

A conifer cone is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in conifers and cycads. The cone of Pinophyta contains the reproductive structures. The woody cone is the female cone, which produces seeds. The male cone, which produces pollen, is usually herbaceous and much less conspicuous even at full maturity. The name "cone" derives from Greek konos, which also gave name to the geometric cone. The individual plates of a cone are known as scales. The umbo of a conifer cone refers to the first year's growth of a seed scale on the cone, showing up as a protuberance at the end of the two-year-old scale.

Araucaria mirabilis

Araucaria mirabilis

Araucaria mirabilis is an extinct species of coniferous tree from Patagonia, Argentina. It belongs to the genus Araucaria.

Patagonia

Patagonia

Patagonia refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and glaciers in the west and deserts, tablelands and steppes to the east. Patagonia is bounded by the Pacific Ocean on the west, the Atlantic Ocean to the east, and many bodies of water that connect them, such as the Strait of Magellan, the Beagle Channel, and the Drake Passage to the south.

Argentina

Argentina

Argentina, officially the Argentine Republic, is a country in the southern half of South America. Argentina covers an area of 2,780,400 km2 (1,073,500 sq mi), making it the second-largest country in South America after Brazil, the fourth-largest country in the Americas, and the eighth-largest country in the world. It shares the bulk of the Southern Cone with Chile to the west, and is also bordered by Bolivia and Paraguay to the north, Brazil to the northeast, Uruguay and the South Atlantic Ocean to the east, and the Drake Passage to the south. Argentina is a federal state subdivided into twenty-three provinces, and one autonomous city, which is the federal capital and largest city of the nation, Buenos Aires. The provinces and the capital have their own constitutions, but exist under a federal system. Argentina claims sovereignty over the Falkland Islands, South Georgia and the South Sandwich Islands, and a part of Antarctica.

Source: "Fossil", Wikipedia, Wikimedia Foundation, (2023, March 24th), https://en.wikipedia.org/wiki/Fossil.

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References
  1. ^ Oxford English Dictionary. Oxford University Press. Archived from the original on 11 January 2008. Retrieved 17 June 2013.
  2. ^ "theNAT :: San Diego Natural History Museum :: Your Nature Connection in Balboa Park :: Frequently Asked Questions". Sdnhm.org. Archived from the original on 10 May 2012. Retrieved 5 November 2012.
  3. ^ Borenstein, Seth (13 November 2013). "Oldest fossil found: Meet your microbial mom". Associated Press. Archived from the original on 29 June 2015. Retrieved 15 November 2013.
  4. ^ Noffke, Nora; Christian, Christian; Wacey, David; Hazen, Robert M. (8 November 2013). "Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ca. 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia". Astrobiology. 13 (12): 1103–24. Bibcode:2013AsBio..13.1103N. doi:10.1089/ast.2013.1030. PMC 3870916. PMID 24205812.
  5. ^ Brian Vastag (21 August 2011). "Oldest 'microfossils' raise hopes for life on Mars". The Washington Post. Archived from the original on 19 October 2011. Retrieved 21 August 2011.
    Wade, Nicholas (21 August 2011). "Geological Team Lays Claim to Oldest Known Fossils". The New York Times. Archived from the original on 1 May 2013. Retrieved 21 August 2011.
  6. ^ a b Borenstein, Seth (19 October 2015). "Hints of life on what was thought to be desolate early Earth". Excite. Yonkers, NY: Mindspark Interactive Network. Associated Press. Archived from the original on 23 October 2015. Retrieved 20 October 2015.
  7. ^ a b Bell, Elizabeth A.; Boehnike, Patrick; Harrison, T. Mark; et al. (19 October 2015). "Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon" (PDF). Proc. Natl. Acad. Sci. U.S.A. 112 (47): 14518–21. Bibcode:2015PNAS..11214518B. doi:10.1073/pnas.1517557112. ISSN 1091-6490. PMC 4664351. PMID 26483481. Archived (PDF) from the original on 6 November 2015. Retrieved 20 October 2015. Early edition, published online before print.
  8. ^ Westall, Frances; et al. (2001). "Early Archean fossil bacteria and biofilms in hydrothermally influenced sediments from the Barberton greenstone belt, South Africa". Precambrian Research. 106 (1–2): 93–116. Bibcode:2001PreR..106...93W. doi:10.1016/S0301-9268(00)00127-3.
  9. ^ Jablonski, David; Roy, Kaustuv; Valentine, James W.; Price, Rebecca M.; Anderson, Philip S. (16 May 2003). "The impact of the pull of the recent on the history of marine diversity". Science. 300 (5622): 1133–1135. Bibcode:2003Sci...300.1133J. doi:10.1126/science.1083246. ISSN 1095-9203. PMID 12750517. S2CID 42468747. Archived from the original on 15 December 2022. Retrieved 15 December 2022.
  10. ^ Sahney, Sarda; Benton, Michael J.; Ferry, Paul A. (23 August 2010). "Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land". Biology Letters. 6 (4): 544–547. doi:10.1098/rsbl.2009.1024. PMC 2936204. PMID 20106856.
  11. ^ Sahney, Sarda; Benton, Michael (2017). "The impact of the Pull of the Recent on the fossil record of tetrapods" (PDF). Evolutionary Ecology Research. 18: 7–23. Archived (PDF) from the original on 15 December 2022. Retrieved 15 December 2022.
  12. ^ Edward B. Daeschler, Neil H. Shubin and Farish A. Jenkins Jr. (6 April 2006). "A Devonian tetrapod-like fish and the evolution of the tetrapod body plan" (PDF). Nature. 440 (7085): 757–763. Bibcode:2006Natur.440..757D. doi:10.1038/nature04639. PMID 16598249. Archived (PDF) from the original on 15 December 2022. Retrieved 15 December 2022.
  13. ^ Prothero, Donald R. (2013). Bringing fossils to life : an introduction to paleobiology (Third ed.). New York: Columbia University Press. p. 8. ISBN 978-0-231-15893-0.
  14. ^ Prothero 2013, pp. 12–13.
  15. ^ Prothero 2013, p. 16.
  16. ^ Prothero 2013, pp. 9–10.
  17. ^ "Definition of Steinkern". Merriam-Webster. Archived from the original on 13 May 2021. Retrieved 13 May 2021. a fossil consisting of a stony mass that entered a hollow natural object (such as a bivalve shell) in the form of mud or sediment, was consolidated, and remained as a cast after dissolution of the mold
  18. ^ Prothero 2013, p. 579.
  19. ^ Prothero 2013, pp. 8–9.
  20. ^ Shute, C. H.; Cleal, C. J. (1986). "Palaeobotany in museums". Geological Curator. 4 (9): 553–559. doi:10.55468/GC865. S2CID 251638416.
  21. ^ Fields H (May 2006). "Dinosaur Shocker – Probing a 68-million-year-old T. rex, Mary Schweitzer stumbled upon astonishing signs of life that may radically change our view of the ancient beasts". Smithsonian Magazine. Archived from the original on 18 January 2015.
  22. ^ Schweitzer MH, Wittmeyer JL, Horner JR, Toporski JK (25 March 2005). "Soft-tissue vessels and cellular preservation in Tyrannosaurus rex". Science. 307 (5717): 1952–5. Bibcode:2005Sci...307.1952S. doi:10.1126/science.1108397. PMID 15790853. S2CID 30456613.
  23. ^ Schweitzer MH, Zheng W, Cleland TP, Bern M (January 2013). "Molecular analyses of dinosaur osteocytes support the presence of endogenous molecules". Bone. 52 (1): 414–23. doi:10.1016/j.bone.2012.10.010. PMID 23085295.
  24. ^ Embery G, Milner AC, Waddington RJ, Hall RC, Langley ML, Milan AM (2003). "Identification of Proteinaceous Material in the Bone of the Dinosaur Iguanodon". Connective Tissue Research. 44 (Suppl 1): 41–6. doi:10.1080/03008200390152070. PMID 12952172. S2CID 2249126.
  25. ^ Schweitzer MH, Zheng W, Cleland TP, Goodwin MB, Boatman E, Theil E, Marcus MA, Fakra SC (November 2013). "A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time". Proceedings of the Royal Society. 281 (1774): 20132741. doi:10.1098/rspb.2013.2741. PMC 3866414. PMID 24285202.
  26. ^ Zylberberg, L.; Laurin, M. (2011). "Analysis of fossil bone organic matrix by transmission electron microscopy". Comptes Rendus Palevol. 11 (5–6): 357–366. doi:10.1016/j.crpv.2011.04.004.
  27. ^ Palmer, T. J.; Wilson, MA (1988). "Parasitism of Ordovician bryozoans and the origin of pseudoborings". Palaeontology. 31: 939–949.
  28. ^ a b Taylor, P. D. (1990). "Preservation of soft-bodied and other organisms by bioimmuration: A review". Palaeontology. 33: 1–17.
  29. ^ Wilson, MA; Palmer, T. J.; Taylor, P. D. (1994). "Earliest preservation of soft-bodied fossils by epibiont bioimmuration: Upper Ordovician of Kentucky". Lethaia. 27 (3): 269–270. doi:10.1111/j.1502-3931.1994.tb01420.x.
  30. ^ "What is paleontology?". University of California Museum of Paleontology. Archived from the original on 16 September 2008. Retrieved 17 September 2008.
  31. ^ a b Fedonkin, M.A.; Gehling, J.G.; Grey, K.; Narbonne, G.M.; Vickers-Rich, P. (2007). The Rise of Animals: Evolution and Diversification of the Kingdom Animalia. JHU Press. pp. 213–216. ISBN 978-0-8018-8679-9. Archived from the original on 17 March 2023. Retrieved 14 November 2008.
  32. ^ e.g. Seilacher, A. (1994). "How valid is Cruziana Stratigraphy?". International Journal of Earth Sciences. 83 (4): 752–758. Bibcode:1994GeoRu..83..752S. doi:10.1007/BF00251073. S2CID 129504434.
  33. ^ "coprolites". Dictionary.com. Archived from the original on 17 December 2008. Retrieved 29 February 2012.
  34. ^ Herron, Scott; Freeman, Jon C. (2004). Evolutionary analysis (3rd ed.). Upper Saddle River, NJ: Pearson Education. p. 816. ISBN 978-0-13-101859-4. Archived from the original on 17 March 2023. Retrieved 11 October 2018.
  35. ^ Neuendorf, Klaus K. E.; Institute, American Geological (2005). Glossary of Geology. Springer Science & Business Media. ISBN 978-0-922152-76-6. Archived from the original on 17 March 2023. Retrieved 7 June 2020.
  36. ^ Ed Strauss (2001). "Petrified Wood from Western Washington". Archived from the original on 11 December 2010. Retrieved 8 April 2011.
  37. ^ Wilson Nichols Stewart; Gar W. Rothwell (1993). Paleobotany and the evolution of plants (2 ed.). Cambridge University Press. p. 31. ISBN 978-0-521-38294-6.
  38. ^ "Subfossils Collections". South Australian Museum. Archived from the original on 17 April 2021. Retrieved 28 August 2020.
  39. ^ "Subfossils Collections". South Australian Museum. Archived from the original on 17 June 2011. Retrieved 23 January 2014.
  40. ^ Peterson, Joseph E.; Lenczewski, Melissa E.; Scherer, Reed P. (October 2010). Stepanova, Anna (ed.). "Influence of Microbial Biofilms on the Preservation of Primary Soft Tissue in Fossil and Extant Archosaurs". PLOS ONE. 5 (10): 13A. Bibcode:2010PLoSO...513334P. doi:10.1371/journal.pone.0013334. PMC 2953520. PMID 20967227.
  41. ^ "Chemical or Molecular Fossils". petrifiedwoodmuseum.org. Archived from the original on 20 April 2014. Retrieved 15 September 2013.
  42. ^ a b Martin, M.W.; Grazhdankin, D.V.; Bowring, S.A.; Evans, D.A.D.; Fedonkin, M.A.; Kirschvink, J.L. (5 May 2000). "Age of Neoproterozoic Bilaterian Body and Trace Fossils, White Sea, Russia: Implications for Metazoan Evolution". Science. 288 (5467): 841–5. Bibcode:2000Sci...288..841M. doi:10.1126/science.288.5467.841. PMID 10797002. S2CID 1019572.
  43. ^ Pufahl, P.K.; Grimm, K.A.; Abed, A.M. & Sadaqah, R.M.Y. (October 2003). "Upper Cretaceous (Campanian) phosphorites in Jordan: implications for the formation of a south Tethyan phosphorite giant". Sedimentary Geology. 161 (3–4): 175–205. Bibcode:2003SedG..161..175P. doi:10.1016/S0037-0738(03)00070-8.
  44. ^ "Geologic Time: Radiometric Time Scale". U.S. Geological Survey. Archived from the original on 21 September 2008. Retrieved 20 September 2008.
  45. ^ Löfgren, A. (2004). "The conodont fauna in the Middle Ordovician Eoplacognathus pseudoplanus Zone of Baltoscandia". Geological Magazine. 141 (4): 505–524. Bibcode:2004GeoM..141..505L. doi:10.1017/S0016756804009227. S2CID 129600604.
  46. ^ a b Gehling, James; Jensen, Sören; Droser, Mary; Myrow, Paul; Narbonne, Guy (March 2001). "Burrowing below the basal Cambrian GSSP, Fortune Head, Newfoundland". Geological Magazine. 138 (2): 213–218. Bibcode:2001GeoM..138..213G. doi:10.1017/S001675680100509X. S2CID 131211543.
  47. ^ Hug, L.A.; Roger, A.J. (2007). "The Impact of Fossils and Taxon Sampling on Ancient Molecular Dating Analyses". Molecular Biology and Evolution. 24 (8): 889–1897. doi:10.1093/molbev/msm115. PMID 17556757.
  48. ^ Peterson, Kevin J.; Butterfield, N.J. (2005). "Origin of the Eumetazoa: Testing ecological predictions of molecular clocks against the Proterozoic fossil record". Proceedings of the National Academy of Sciences. 102 (27): 9547–52. Bibcode:2005PNAS..102.9547P. doi:10.1073/pnas.0503660102. PMC 1172262. PMID 15983372.
  49. ^ a b Prothero, Donald R. (2007). Evolution: What the Fossils Say and Why It Matters. Columbia University Press. pp. 50–53. ISBN 978-0-231-51142-1.
  50. ^ Isaak, M (5 November 2006). "Claim CC200: There are no transitional fossils". TalkOrigins Archive. Archived from the original on 27 February 2009. Retrieved 30 April 2009.
  51. ^ Donovan, S. K.; Paul, C. R. C., eds. (1998). The Adequacy of the Fossil Record. New York: Wiley. p. 312. ISBN 978-0-471-96988-4.
  52. ^ Riding, R. (2007). "The term stromatolite: towards an essential definition". Lethaia. 32 (4): 321–330. doi:10.1111/j.1502-3931.1999.tb00550.x. Archived from the original on 2 May 2015.
  53. ^ "Stromatolites, the Oldest Fossils". Archived from the original on 9 March 2007. Retrieved 4 March 2007.
  54. ^ a b Lepot, Kevin; Benzerara, Karim; Brown, Gordon E.; Philippot, Pascal (2008). "Microbially influenced formation of 2.7 billion-year-old stromatolites". Nature Geoscience. 1 (2): 118–21. Bibcode:2008NatGe...1..118L. doi:10.1038/ngeo107.
  55. ^ a b Allwood, Abigail C.; Grotzinger, John P.; Knoll, Andrew H.; Burch, Ian W.; Anderson, Mark S.; Coleman, Max L.; Kanik, Isik (2009). "Controls on development and diversity of Early Archean stromatolites". Proceedings of the National Academy of Sciences. 106 (24): 9548–9555. Bibcode:2009PNAS..106.9548A. doi:10.1073/pnas.0903323106. PMC 2700989. PMID 19515817.
  56. ^ Schopf, J. William (1999). Cradle of life: the discovery of earth's earliest fossils. Princeton, N.J: Princeton University Press. pp. 87–89. ISBN 978-0-691-08864-8. Archived from the original on 17 March 2023. Retrieved 11 October 2018.
  57. ^ McMenamin, M. A. S. (1982). "Precambrian conical stromatolites from California and Sonora". Bulletin of the Southern California Paleontological Society. 14 (9&10): 103–105.
  58. ^ McNamara, K.J. (20 December 1996). "Dating the Origin of Animals". Science. 274 (5295): 1993–1997. Bibcode:1996Sci...274.1993M. doi:10.1126/science.274.5295.1993f.
  59. ^ Awramik, S.M. (19 November 1971). "Precambrian columnar stromatolite diversity: Reflection of metazoan appearance". Science. 174 (4011): 825–827. Bibcode:1971Sci...174..825A. doi:10.1126/science.174.4011.825. PMID 17759393. S2CID 2302113.
  60. ^ Bengtson, S. (2002). "Origins and early evolution of predation" (PDF). In Kowalewski, M.; Kelley, P.H. (eds.). The fossil record of predation. The Paleontological Society Papers. Vol. 8. The Paleontological Society. pp. 289–317. Archived (PDF) from the original on 10 September 2008. Retrieved 29 December 2014.
  61. ^ Sheehan, P.M.; Harris, M.T. (2004). "Microbialite resurgence after the Late Ordovician extinction". Nature. 430 (6995): 75–78. Bibcode:2004Natur.430...75S. doi:10.1038/nature02654. PMID 15229600. S2CID 4423149.
  62. ^ Riding R (March 2006). "Microbial carbonate abundance compared with fluctuations in metazoan diversity over geological time" (PDF). Sedimentary Geology. 185 (3–4): 229–38. Bibcode:2006SedG..185..229R. doi:10.1016/j.sedgeo.2005.12.015. Archived from the original (PDF) on 26 April 2012. Retrieved 9 December 2011.
  63. ^ Adams, E. W.; Grotzinger, J. P.; Watters, W. A.; Schröder, S.; McCormick, D. S.; Al-Siyabi, H. A. (2005). "Digital characterization of thrombolite-stromatolite reef distribution in a carbonate ramp system (terminal Proterozoic, Nama Group, Namibia)" (PDF). AAPG Bulletin. 89 (10): 1293–1318. doi:10.1306/06160505005. Archived from the original (PDF) on 7 March 2016. Retrieved 8 December 2011.
  64. ^ The MEPAG Astrobiology Field Laboratory Science Steering Group (26 September 2006). "Final report of the MEPAG Astrobiology Field Laboratory Science Steering Group (AFL-SSG)" (.doc). In Steele, Andrew; Beaty, David (eds.). The Astrobiology Field Laboratory. U.S.A.: Mars Exploration Program Analysis Group (MEPAG) – NASA. p. 72. Archived from the original on 11 May 2020. Retrieved 29 December 2014.
  65. ^ a b 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.
  66. ^ a b Various (24 January 2014). "Special Issue – Table of Contents – Exploring Martian Habitability". Science. 343 (6169): 345–452. Archived from the original on 29 January 2014. Retrieved 24 January 2014.
  67. ^ Various (24 January 2014). "Special Collection – Curiosity – Exploring Martian Habitability". Science. Archived from the original on 28 January 2014. Retrieved 24 January 2014.
  68. ^ Grotzinger, J.P.; et al. (24 January 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. S2CID 52836398.
  69. ^ a b c "Prehistoric Fossil Collectors". Archived from the original on 17 February 2019. Retrieved 16 February 2019.
  70. ^ "Ancient Egyptians Collected Fossils". 5 September 2016. Archived from the original on 10 February 2019. Retrieved 9 February 2019.
  71. ^ "The Internet Classics Archive | Meteorology by Aristotle". classics.mit.edu. Archived from the original on 18 February 2014. Retrieved 20 February 2023.
  72. ^ Rudwick, M. J. S. (1985). The Meaning of Fossils: Episodes in the History of Palaeontology. University of Chicago Press. p. 24. ISBN 978-0-226-73103-2. Archived from the original on 17 March 2023. Retrieved 11 October 2018.
  73. ^ a b c "Cartilaginous fish". Archived from the original on 30 July 2017. Retrieved 16 February 2019.
  74. ^ "References to fossils by Pliny the Elder". Archived from the original on 2 January 2019. Retrieved 16 February 2019.
  75. ^ Mayor, Adrienne (24 October 2013). Fossil Legends of the First Americans. Princeton University Press. ISBN 978-1-4008-4931-4. Archived from the original on 17 March 2023. Retrieved 18 October 2019 – via Google Books.
  76. ^ "How we know that ancient African people valued fossils and rocks". Archived from the original on 10 February 2019. Retrieved 9 February 2019.
  77. ^ "4億年前"書法化石"展出 黃庭堅曾刻下四行詩[圖]" [400 million-year-old fossil appeared in exhibition with poem by Huang Tingjian]. People's Daily Net (in Traditional Chinese). 17 May 2013. Archived from the original on 12 June 2018. Retrieved 7 June 2018.
  78. ^ Sivin, Nathan (1995). Science in Ancient China: Researches and Reflections. Brookfield, Vermont: VARIORUM, Ashgate Publishing. III, p. 23
  79. ^ a b Needham, Joseph. (1959). Science and Civilization in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth. Cambridge University Press. pp. 603–618.
  80. ^ Chan, Alan Kam-leung and Gregory K. Clancey, Hui-Chieh Loy (2002). Historical Perspectives on East Asian Science, Technology and Medicine. Singapore: Singapore University Press. p. 15. ISBN 9971-69-259-7.
  81. ^ Rafferty, John P. (2012). Geological Sciences; Geology: Landforms, Minerals, and Rocks. New York: Britannica Educational Publishing, p. 6. ISBN 9781615305445
  82. ^ Desmond, Adrian. "The Discovery of Marine Transgressions and the Explanation of Fossils in Antiquity," American Journal of Science, 1975, Volume 275: 692–707.
  83. ^ Rafferty, John P. (2012). Geological Sciences; Geology: Landforms, Minerals, and Rocks. New York: Britannica Educational Publishing, pp. 5–6. ISBN 9781615305445.
  84. ^ Alistair Cameron Crombie (1990). Science, optics, and music in medieval and early modern thought. Continuum International Publishing Group. pp. 108–109. ISBN 978-0-907628-79-8. Archived from the original on 17 March 2023. Retrieved 11 October 2018.
  85. ^ "Cyclops Myth Spurred by 'One-Eyed' Fossils?". National Geographic Society. 5 February 2003. Archived from the original on 17 February 2019. Retrieved 16 February 2019.
  86. ^ "8 Types of Imaginary Creatures "Discovered" In Fossils". 19 May 2015. Archived from the original on 16 February 2019. Retrieved 16 February 2019.
  87. ^ "Folklore of Fossil Echinoderms". 4 April 2017. Archived from the original on 17 February 2019. Retrieved 16 February 2019.
  88. ^ McNamara, Kenneth J. (2007). "Shepherds' crowns, fairy loaves and thunderstones: the mythology of fossil echinoids in England". Geological Society, London, Special Publications. 273 (1): 279–294. Bibcode:2007GSLSP.273..279M. doi:10.1144/GSL.SP.2007.273.01.22. S2CID 129384807. Archived from the original on 21 February 2019. Retrieved 16 February 2019.
  89. ^ "Archaeological Echinoderm! Fairy Loaves & Thunderstones!". 12 January 2009. Archived from the original on 17 February 2019. Retrieved 16 February 2019.
  90. ^ "WMNH - Geology and Astronomy". www.wmnh.com. Archived from the original on 13 February 2019. Retrieved 20 February 2023.
  91. ^ da Vinci, Leonardo (1956) [1938]. The Notebooks of Leonardo da Vinci. London: Reynal & Hitchcock. p. 335. ISBN 978-0-9737837-3-5.
  92. ^ Bressan, David. "July 18, 1635: Robert Hooke – The Last Virtuoso of Silly Science". Scientific American Blog Network. Archived from the original on 12 February 2018. Retrieved 11 February 2018.
  93. ^ "Cuvier". palaeo.gly.bris.ac.uk. Archived from the original on 25 May 2014. Retrieved 3 November 2008.
  94. ^ "Mary Anning". Lyme Regis Museum. Archived from the original on 22 August 2018. Retrieved 21 August 2018.
  95. ^ Darwin, Charles, "Chapter X: On the Imperfection of the Geological Record", The Origin of Species, archived from the original on 6 February 2023, retrieved 20 February 2023
  96. ^ Schopf JW (1999) Cradle of Life: The Discovery of the Earth's Earliest Fossils, Princeton University Press, Princeton, NJ.
  97. ^ "The Virtual Fossil Museum – Fossils Across Geological Time and Evolution". Archived from the original on 8 March 2007. Retrieved 4 March 2007.
  98. ^ Knoll, A, (2003) Life on a Young Planet. (Princeton University Press, Princeton, NJ)
  99. ^ Donovan, S. K.; Paul, C. R. C., eds. (1998). "An Overview of the Completeness of the Fossil Record". The Adequacy of the Fossil Record. New York: Wiley. pp. 111–131. ISBN 978-0-471-96988-4.
  100. ^ Fortey, Richard, Trilobite!: Eyewitness to Evolution. Alfred A. Knopf, New York, 2000.
  101. ^ Donoghue, PCJ; Bengtson, S; Dong, X; Gostling, NJ; Huldtgren, T; Cunningham, JA; Yin, C; Yue, Z; Peng, F; et al. (2006). "Synchrotron X-ray tomographic microscopy of fossil embryos". Nature. 442 (7103): 680–683. Bibcode:2006Natur.442..680D. doi:10.1038/nature04890. PMID 16900198. S2CID 4411929.
  102. ^ Foote, M.; Sepkoski, J.J. Jr (1999). "Absolute measures of the completeness of the fossil record". Nature. 398 (6726): 415–417. Bibcode:1999Natur.398..415F. doi:10.1038/18872. PMID 11536900. S2CID 4323702.
  103. ^ Benton, M. (2009). "The completeness of the fossil record". Significance. 6 (3): 117–121. doi:10.1111/j.1740-9713.2009.00374.x. S2CID 84441170.
  104. ^ Žliobaitė, I.; Fortelius, M. (2021). "On calibrating the completometer for the mammalian fossil record". Paleobiology. 48: 1–11. doi:10.1017/pab.2021.22. S2CID 238686414.
  105. ^ Eiting, T.P.; Gunnell, G.G (2009). "Global Completeness of the Bat Fossil Record". Journal of Mammalian Evolution. 16 (3): 151–173. doi:10.1007/s10914-009-9118-x. S2CID 5923450.
  106. ^ Brocklehurst, N.; Upchurch, P.; Mannion, P.D.; O'Connor, J. (2012). "The Completeness of the Fossil Record of Mesozoic Birds: Implications for Early Avian Evolution". PLOS ONE. 7 (6): e39056. Bibcode:2012PLoSO...739056B. doi:10.1371/journal.pone.0039056. PMC 3382576. PMID 22761723.
  107. ^ Retallack, G. (1984). "Completeness of the rock and fossil record: some estimates using fossil soils". Paleobiology. 10 (1): 59–78. doi:10.1017/S0094837300008022. S2CID 140168970.
  108. ^ Benton, M.J.; Storrs, G.Wm. (1994). "Testing the quality of the fossil record: Paleontological knowledge is improving". Geology. 22 (2): 111–114. Bibcode:1994Geo....22..111B. doi:10.1130/0091-7613(1994)0222.3.CO;2.
  109. ^ Holland, S.M.; Patzkowsky, M.E. (1999). "Models for simulating the fossil record". Geology. 27 (6): 491–494. Bibcode:1999Geo....27..491H. doi:10.1130/0091-7613(1999)0272.3.CO;2.
  110. ^ Koch, C. (1978). "Bias in the published fossil record". Paleobiology. 4 (3): 367–372. doi:10.1017/S0094837300006060. S2CID 87368101.
  111. ^ Signore, P.W. III; Lipps, J.H. (1982). "Sampling bias, gradual extinction patterns and catastrophes in the fossil record". In Silver, L.T.; Schultz, P.H. (eds.). Geological Implications of Impacts of Large Asteroids and Comets on the Earth. Geological Society of America Special Papers. Vol. 190. pp. 291–296. doi:10.1130/SPE190-p291. ISBN 0-8137-2190-3.
  112. ^ Vilhena, D.A.; Smith, A.B. (2013). "Spatial Bias in the Marine Fossil Record". PLOS ONE. 8 (10): e74470. Bibcode:2013PLoSO...874470V. doi:10.1371/journal.pone.0074470. PMC 3813679. PMID 24204570.
  113. ^ Bosscher, M. (2014). Mythical monsters and ancient fossils [Message on a blog]
  114. ^ Mayor, A. (2000). The “Monster of Troy” Vase: The Earliest Artistic Record of a Vertebrate Fossil Discovery? Oxford Journal of Archaeology, 19(1), 57-63. doi https://doi.org/10.1111/1468-0092.00099
  115. ^ Monge-Nájera, Julián (31 January 2020). "Evaluation of the hypothesis of the Monster of Troy vase as the earliest artistic record of a vertebrate fossil". Uniciencia. 34 (1): 147–151. doi:10.15359/ru.34-1.9. ISSN 2215-3470. S2CID 208591414. Archived from the original on 20 February 2023. Retrieved 20 February 2023.
  116. ^ Milmo, Cahal (25 November 2009). "Fossil theft: One of our dinosaurs is missing". The Independent. London. Archived from the original on 28 November 2009. Retrieved 2 May 2010.
    Simons, Lewis. "Fossil Wars". National Geographic. The National Geographic Society. Archived from the original on 27 February 2012. Retrieved 29 February 2012.
    Willis, Paul; Clark, Tim; Dennis, Carina (18 April 2002). "Fossil Trade". Catalyst. Archived from the original on 24 May 2012. Retrieved 29 February 2012.
    Farrar, Steve (5 November 1999). "Cretaceous crimes that fuel the fossil trade". Times Higher Education. Archived from the original on 20 August 2012. Retrieved 2 November 2011.
  117. ^ Williams, Paige. "The Black Market for Dinosaurs". The New Yorker. Archived from the original on 22 September 2020. Retrieved 7 September 2020.
  118. ^ van der Geer, Alexandra; Dermitzakis, Michael (2010). "Fossils in pharmacy: from "snake eggs" to "Saint's bones"; an overview" (PDF). Hellenic Journal of Geosciences. 45: 323–332. Archived from the original (PDF) on 19 June 2013.
  119. ^ "Chinese villagers ate dinosaur 'dragon bones'". MSNBC. Associated Press. 5 July 2007. Archived from the original on 22 January 2020. Retrieved 7 March 2020.
External links
Preceded by Stages of human development
Fossilization
Succeeded by
None

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