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Definição e significado de Fossils

fossils

  • plural of fossil (noun)

Definição

Fossils (n.)

1.(MeSH)the remains (or an impression) of a plant or animal that existed in a past geological age and that has been excavated from the soil

2.(MeSH)Remains, impressions, or traces of animals or plants of past geological times which have been preserved in the earth's crust.

fossil (adj.)

1.characteristic of a fossil

fossil (n.)

1.the remains (or an impression) of a plant or animal that existed in a past geological age and that has been excavated from the soil

2.Remains, impressions, or traces of animals or plants of past geological times which have been preserved in the earth's crust.

3.someone whose style is out of fashion

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Merriam Webster

FossilFos"sil (?), a. [L. fossilis, fr. fodere to dig: cf. F. fossile. See Fosse.]
1. Dug out of the earth; as, fossil coal; fossil salt.

2. preserved from a previous geological age; as, fossil water from deep wells; -- usually implying that the object so described has had its substance modified by long residence in the ground, but also used (as with fossil water) in cases where chemical composition is not altered.

3. (Paleon.) Like or pertaining to fossils; contained in rocks, whether petrified or not; as, fossil plants, shells.

Fossil copal, a resinous substance, first found in the blue clay at Highgate, near London, and apparently a vegetable resin, partly changed by remaining in the earth. -- Fossil cork, Fossil flax, Fossil paper, or Fossil wood, varieties of amianthus. -- Fossil farina, a soft carbonate of lime. -- Fossil ore, fossiliferous red hematite. Raymond.

FossilFos"sil, n.
1. A substance dug from the earth. [Obs.]

☞ Formerly all minerals were called fossils, but the word is now restricted to express the remains of animals and plants found buried in the earth. Ure.

2. (Paleon.) The remains of an animal or plant found in stratified rocks. Most fossils belong to extinct species, but many of the later ones belong to species still living.

3. A person whose views and opinions are extremely antiquated; one whose sympathies are with a former time rather than with the present. [Colloq.]

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Definiciones (más)

definição - Wikipedia

Sinónimos

Fossils (n.) (MeSH)

fossil

fossil (n.)

dodo, fogey, fogy, old fart, Fossils  (MeSH)

Ver também

Fossils (n.)

fossil, fossiliferous

fossil (n.)

fossiliferous prehistoric

fossil (adj.)

Locuções

2009 extinct fossil octopus discoveries • Agate Fossil Beds National Monument • Ashfall Fossil Beds • Ashfall Fossil Beds State Historical Park • Assistant Secretary of Energy for Fossil Energy • Bitter Springs (fossil locality) • Bob Fossil • Bull Run Fossil Plant • Byblos Fossil Museum • Canadian Fossil Discovery Centre • Clarkia fossil beds • Coliseum Mineral, Fossil, Gem, and Jewelry Show • Colorado state fossil • Compression fossil • Costa da Caparica Fossil Cliff Protected Landscape • Daedalus (trace fossil) • Dakota (fossil) • Dali (fossil) • Danny Dunn and the Fossil Cave • Derived fossil • Florissant Fossil Beds National Monument • Flue gas emissions from fossil fuel combustion • Fossil (disambiguation) • Fossil (file system) • Fossil (novel) • Fossil (software) • Fossil Bluff • Fossil Butte National Monument • Fossil Cabin • Fossil Coral Reef • Fossil Creek • Fossil Creek Bridge • Fossil Cycad National Monument • Fossil Detectives • Fossil Falls • Fossil Fighters • Fossil Fools Day • Fossil Forest • Fossil Forest, Dorset • Fossil Fuel Beta • Fossil Fuel Levy • Fossil Fuel Records • Fossil Fuels Brewing Company • Fossil Fun Games • Fossil Grove • Fossil Hill Public School • Fossil Hunter • Fossil Monotremes • Fossil Mountain • Fossil Mountain (Alberta) • Fossil Mountain (Wyoming) • Fossil Parks of India • Fossil Ridge High School • Fossil Ridge High School (Fort Collins, Colorado) • Fossil Ridge High School (Fort Worth, Texas) • Fossil Ridge Wilderness • Fossil Rim Wildlife Center • Fossil Springs Wilderness • Fossil alkali • Fossil beach • Fossil collecting • Fossil collecting code • Fossil embryos • Fossil fuel • Fossil fuel exporters • Fossil fuel phase out • Fossil fuel power station • Fossil fuel reforming • Fossil group • Fossil park • Fossil record of fire • Fossil springsnail • Fossil trackway • Fossil trade • Fossil water • Fossil wood • Fossil word • Fossil, Inc. • Fossil, Oregon • Future Fossil Records • Gilboa Fossil Forest • God-Apes and Fossil Men • Gray Fossil Site • Hagerman Fossil Beds National Monument • Ida (fossil) • Index fossil • Indroda Dinosaur and Fossil Park • John Day Fossil Beds National Monument • Kingston Fossil Plant • Kingston Fossil Plant coal fly ash slurry spill • Kromdraai fossil site • List of fossil birds • List of fossil parks • List of fossil primates • List of fossil sites • List of marine gastropod genera in the fossil record • List of non-Dinosauria fossil trackway articles • Living fossil • Mazon Creek fossil beds • Montana state fossil • Mt. Blanco Fossil Museum • National Fossil Wood Park, Tiruvakkarai • New Mexico state fossil • Non-Fossil Fuel Obligation • Pauline Fossil • Petrova Fossil • Polystrate fossil • Posy Fossil • Pseudo-fossil • Riker Hill Fossil Site • Saketi Fossil Park • Shaniko-Fossil Highway • Shivalik Fossil Park • Stonerose Interpretive Center and Fossil Site • The Fossil • The Fossil Island • Trace fossil • Trace fossil classification • Transitional fossil • Upright fossil • Upstream (fossil-fuel industry) • West coast fossil park • Wheeler High School (Fossil, Oregon) • Windley Key Fossil Reef Geological State Park • Wyoming state fossil • Zero Emission Fossil Fuel Power Plants

Dicionario analógico

Fossils (n.) [MeSH]

fossil[ClasseHyper.]

fossil[ClasseHyper.]

géologie (fr)[DomainRegistre]

Paleontology[Hyper.]


Wikipedia - ver também

Wikipedia

Fossil

                   
  Three small ammonite fossils, each approximately 1.5 cm across
  Eocene fossil fish Priscacara liops from Green River Formation of Wyoming
  Petrified wood. The internal structure of the tree and bark are maintained in the permineralization process.

Fossils (from Latin fossus, literally "having been dug up") are the preserved remains or traces of animals (also known as zoolites), plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record.

The study of fossils across geological time, how they were formed, and the evolutionary relationships between taxa (phylogeny) are some of the most important functions of the science of paleontology. Such a preserved specimen is called a "fossil" if it is older than some minimum age, most often the arbitrary date of 10,000 years ago.[1] Hence, fossils range in age from the youngest at the start of the Holocene Epoch to the oldest from the Archaean Eon, up to 3.4 billion years old.[2][3] The observations that certain fossils were associated with certain rock strata led early geologists to recognize a geological timescale in the 19th century. The development of radiometric dating techniques in the early 20th century allowed geologists to determine the numerical or "absolute" age of the various strata and thereby the included fossils.

Like extant organisms, fossils vary in size from microscopic, such as single bacterial cells[4] only one micrometer in diameter, to gigantic, such as 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. Preservation of soft tissues is rare in the fossil record. Fossils may also consist of the marks left behind by the organism while it was alive, such as the footprint or feces (coprolites) of a reptile. These types of fossil are called trace fossils (or ichnofossils), as opposed to body fossils. Finally, past life leaves some markers that cannot be seen but can be detected in the form of biochemical signals; these are known as chemofossils or biomarkers.

Contents

Developments in interpretation of the fossil record

  Silurian Orthoceras Fossil

Ever since recorded history began, and probably before, people have noticed and gathered fossils, including pieces of rock and minerals that have replaced the remains of biologic organisms, or preserved their external form. Fossils themselves, and the totality of their occurrence within the sequence of Earth's rock strata, is referred to as the fossil record.

The fossil record was one of the early sources of data relevant to the study of evolution and continues to be relevant to the history of life on Earth. Paleontologists examine the fossil record in order to understand the process of evolution and the way particular species have evolved.

Explanations

  Fossil shrimp (Cretaceous)
  A fossil gastropod from the Pliocene of Cyprus. A serpulid worm is attached.

Various explanations have been put forth throughout history to explain what fossils are and how they came to be where they were found. Many of these explanations relied on folktales or mythologies. In China the fossil bones of ancient mammals including Homo erectus were often mistaken for “dragon bones” and used as medicine and aphrodisiacs. In the West the presence of fossilized sea creatures high up on mountainsides was seen as proof of the biblical deluge.

In 1027, the Persian Avicenna explained how the stoniness of fossils was caused in The Book of Healing. Avicenna gave the following explanation for the origin of fossils from the petrifaction of plants and animals:

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.[5]

Greek scholar Aristotle realized that fossil seashells from rocks were similar to those found on the beach, indicating the fossils were once living animals. Leonardo da Vinci concurred with Aristotle's view that fossils were the remains of ancient life.[6] Aristotle previously explained it in terms of vaporous exhalations, which Avicenna modified into the theory of petrifying fluids (succus lapidificatus), which was elaborated on by Albert of Saxony in the 14th century and accepted in some form by most naturalists by the 16th century.[7]

More scientific views of fossils emerged during the Renaissance. For example, Leonardo Da Vinci noticed discrepancies with the use of 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...."[8]
  Ichthyosaurus and Plesiosaurus from the 1834 Czech edition of Cuvier's Discours sur les revolutions de la surface du globe.

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.

Smith, who preceded Charles Darwin, was unaware of biological evolution and did not know why faunal succession occurred. Biological evolution explains why faunal succession exists: as different organisms evolve, change and go extinct, they leave behind fossils. Faunal succession was one of the chief pieces of evidence cited by Darwin that biological evolution had occurred.

Georges Cuvier came to believe that most if not all the animal fossils he examined were remains of species that were now extinct. 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.[9]

Biological explanations

Early naturalists well understood the similarities and differences of living species leading Linnaeus to develop a hierarchical classification system still in use today. It was Darwin and his contemporaries who first linked the hierarchical structure of the great tree of life in living organisms 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.

  Petrified cone of Araucaria mirabilis from Patagonia, Argentina dating from the Jurassic Period (approx. 210 Ma)

When Charles 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. The absence of older fossils worried Darwin about the implications for 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.[10]

Further discoveries

Since Darwin's time, the fossil record has been pushed back to between 2.3 and 3.5 billion years before the present.[11] 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 the fossils they contain. 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. Various dating methods have been used and are used today depending on local geology and context, and while there is some variance in the results from these dating methods, nearly all of them provide evidence for a very old Earth, approximately 4.6 billion years.

Modern view

"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."[12] The earth’s climate, tectonics, atmosphere, oceans, and periodic disasters invoked the primary selective pressures on all organisms, which they either adapted to, or they perished with or without leaving descendants. Modern paleontology has joined with evolutionary biology to share the interdisciplinary task of unfolding the tree of life, which inevitably leads backwards in time to the microscopic life of the Precambrian 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."[13] Molecular biologists, using phylogenetics, can compare protein amino acid or nucleotide sequence homology (i.e., similarity) to infer taxonomy and evolutionary distances among organisms, but with limited statistical confidence. The study of fossils, on the other hand, can more specifically pinpoint when and in what organism branching occurred in the tree of life. Modern phylogenetics and paleontology work together in the clarification of science’s still dim view of the appearance of life and its evolution during deep time on earth.[14]

  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; scale in mm

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.[15] 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 the seminal paper on punctuated equilibrium in 1971.

Example of modern development

An example of modern paleontological progress is the application of synchrotron X-ray tomographic techniques to early Cambrian bilaterian embryonic microfossils that has recently 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.[16]

Rarity of fossils

  Megalodon and Carcharodontosaurus teeth. The latter was found in the Sahara Desert.
  Eocene fossil flower, collected August 2010 from Clare family fossil quarry, Florissant, Colorado

Fossilization is an exceptionally rare occurrence, because most components of formerly living things tend to decompose relatively quickly following death. In order for an organism to be fossilized, the remains normally need to be covered by sediment as soon as possible. However there are exceptions to this, such as if an organism becomes frozen, desiccated, or comes to rest in an anoxic (oxygen-free) environment. There are several different types of fossils and fossilization processes.

Due to the combined effect of taphonomic processes and simple mathematical chance, fossilization tends to favor organisms with hard body parts, those that were widespread, and those that existed for a long time before going extinct. On the other hand, it is very unusual to find fossils of small, soft bodied, geographically restricted and geologically ephemeral organisms, because of their relative rarity and low likelihood of preservation.

Larger specimens (macrofossils) are more often observed, dug up and displayed, although microscopic remains (microfossils) are actually far more common in the fossil record.

Some casual observers have been perplexed by the rarity of transitional species within the fossil record. The conventional explanation for this rarity was given by Darwin, who stated that "the extreme imperfection of the geological record," combined with the short duration and narrow geographical range of transitional species, made it unlikely that many such fossils would be found. Simply put, the conditions under which fossilization takes place are quite rare; and it is highly unlikely that any given organism will leave behind a fossil. Eldredge and Gould developed their theory of punctuated equilibrium in part to explain the pattern of stasis and sudden appearance in the fossil record. Furthermore, in the strictest sense, nearly all fossils are "transitional," due to the improbability that any given fossil represents the absolute termination of an evolutionary path.

Types of preservation

Permineralization

  A permineralized trilobite, Asaphus kowalewskii

Permineralization occurs after burial, as the empty spaces within an organism (spaces filled with liquid or gas during life) become filled with mineral-rich groundwater and the minerals precipitate from the groundwater, thus 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. For permineralization to occur, the organism must become covered by sediment soon after death or soon after the initial decaying process. 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. This is a form of diagenesis.

  External mold of a bivalve from the Logan Formation, Lower Carboniferous, Ohio
  Recrystallized scleractinian coral (aragonite to calcite) from the Jurassic of southern Israel

Casts and molds

In some cases the original remains of the organism have been completely dissolved or otherwise destroyed. When all that is left is an organism-shaped hole in the rock, it is called an external mold. If this hole is later filled with other minerals, it is a cast. An endocast or internal mold is formed when sediments or minerals fill the internal cavity of an organism, such as the inside of a bivalve or snail or the hollow of a skull.

Authigenic mineralisation

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 authigenic mineralisation.

Replacement and recrystallization

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.

Adpression (compression-impression) fossils

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, it has proved to convenient to have a combined term for both modes of preservation: adpression.[17]

Bioimmuration

  The star-shaped holes (Catellocaula vallata) in this Upper Ordovician bryozoan represent a soft-bodied organism preserved by bioimmuration in the bryozoan skeleton.[18]

Bioimmuration is a type of preservation in which a skeletal organism overgrows or otherwise subsumes another organism, preserving the latter, or an impression of it, within the skeleton.[19] 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 and grows upwards, preserving the settler in its skeleton. Bioimmuration is known in the fossil record from the Ordovician[20] to the Recent.[19]

To sum up, fossilization processes proceed differently for different kinds of tissues and under different kinds of conditions.

Fossil sites

Fossil sites with exceptional preservation—sometimes including preserved soft tissues—are known as Lagerstätten. These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying 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.

Earliest fossiliferous sites

  Lower Proterozoic Stromatolites from Bolivia, South America

Earth’s oldest fossils are the stromatolites consisting of rock built from layer upon layer of sediment and other precipitants.[21] Based on studies of now-rare (but living) stromatolites (specifically, certain blue-green bacteria), the growth of fossil stromatolitic structures was biogenetically mediated by mats of microorganisms through their entrapment of sediments. However, abiotic mechanisms for stromatolitic growth are also known, leading to a decades-long and sometimes-contentious scientific debate regarding biogenesis of certain formations, especially those from the lower to middle Archean eon.

It is most widely accepted that stromatolites from the late Archean and through the middle Proterozoic eon were mostly formed by massive colonies of cyanobacteria (formerly known as blue-green "algae"), and that the oxygen byproduct of their photosynthetic metabolism first resulted in earth’s massive banded iron formations and subsequently oxygenated earth’s atmosphere.

Even though it is extremely rare, microstructures resembling cells are sometimes found within stromatolites; but these are also the source of scientific contention. The Gunflint Chert contains abundant microfossils widely accepted as a diverse consortium of 2.0 Ga Microorganisms.[22]

In contrast, putative fossil cyanobacteria cells from the 3.4 Ga Warrawoona Group in Western Australia are in dispute since abiotic processes cannot be ruled out.[23] Confirmation of the Warrawoona microstructures as cyanobacteria would profoundly impact our understanding of when and how early life diversified, pushing important evolutionary milestones further back in time. The continued study of these oldest fossils is paramount to calibrate complementary molecular phylogenetics models.

Types

Index fossil

  Examples of index fossils

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 laid down, they may include the remains of the same species of fossil. If the species concerned were short-lived (in geological terms, lasting a few hundred thousand years), then it is certain that the sediments in question were deposited within that narrow time period. The shorter the lifespan of a species, the more precisely different sediments can be correlated, and so rapidly evolving types of 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 minor.

Trace fossils

  A coprolite of a carnivorous dinosaur found in southwestern Saskatchewan.

Trace fossils are the remains of trackways, burrows, bioerosion, eggs and eggshells, nests, droppings and other types of impressions. Fossilized droppings, called coprolites, can give insight into the feeding behavior of animals and can therefore be of great importance. 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.[24] Coprolites may range in size from a few millimetres to over 60 centimetres.

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.[25] 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

'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, although this is only an approximate guide. 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 fossils

  Leptofoenus pittfieldae trapped in Dominican amber, from 20 to 16 million years ago

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 Tertiary. The excretion of the resin by certain plants is thought to be an evolutionary adaptation for protection from insects and to seal wounds caused by damage elements. 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 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 made significantly later than when the fossilized animal or plant died:[26][27] it happens when a hard fossil is freed from a soft rock formation by erosion and redeposited in a currently forming sedimentary deposit.

Fossil wood

  petrified softwood

Fossil wood is wood that is preserved in the fossil record. Over time the wood will usually be 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, with the rest of the plant completely unknown:[28] 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).[29]

Mistaken for fossils

Pseudofossils

  Manganese dendrites on a limestone bedding plane from Solnhofen, Germany; scale in mm

Pseudofossils are visual patterns in rocks that are produced by naturally occurring geologic processes rather than biologic processes. They can easily be mistaken for real fossils. Some pseudofossils, such as dendrites, 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.

  Ginkgo biloba Eocene fossil, McAbee, B.C., Canada

Living fossils

Living fossil is an informal term used for any living species that is apparently identical or closely resembles a species previously known only from fossils—that is, it is as if the ancient fossil had "come to life."

This can be (a) a species or taxon known only from fossils until living representatives were discovered, such as the lobe-finned coelacanth, primitive monoplacophoran mollusk, and the Chinese maidenhair tree, or (b) a single living species with no close relatives, such as the New Caledonian Kagu, or the Sunbittern, or (c) a small group of closely related species with no other close relatives, such as the oxygen-producing, primordial stromatolite, inarticulate lampshell Lingula, many-chambered pearly Nautilus, rootless whisk fern, armored horseshoe crab, and dinosaur-like tuatara that are the sole survivors of a once large and widespread groups in the fossil record.

Fossil trading and collecting

Fossil Trading

Fossil trading is the practice of buying and selling fossils. This is many times done illegally with stolen fossils, and many important scientific specimens are lost each year.[30][31][32][33] Much focus has been put on the illegal fossil dealing in China, where many specimens have been stolen.[34]

Fossil collecting

Fossil collecting (some times, 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.

See also

References

  1. ^ Frequently Asked Questions about Paleontology. San Diego Natural History Museum
  2. ^ "Oldest ‘microfossils’ raise hopes for life on Mars". The Washington Post. 21 August 2011. http://www.washingtonpost.com/national/health-science/oldest-microfossils-hail-from-34-billion-years-ago-raise-hopes-for-life-on-mars/2011/08/19/gIQAHK8UUJ_story.html?hpid=z3. Retrieved 2011-08-21. 
  3. ^ Wade, Nicholas (21 August 2011). "Geological Team Lays Claim to Oldest Known Fossils". The New York Times. http://www.nytimes.com/2011/08/22/science/earth/22fossil.html?_r=1&partner=rss&emc=rss&src=ig. Retrieved 2011-08-21. 
  4. ^ 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. DOI:10.1016/S0301-9268(00)00127-3. http://ieg.or.kr:8080/abstractII/E0210601006.html. 
  5. ^ Alistair Cameron Crombie (1990). Science, optics, and music in medieval and early modern thought. Continuum International Publishing Group. pp. 108–109. ISBN 0-907628-79-6. 
  6. ^ Correlating Earth's History, Paul R. Janke
  7. ^ Rudwick, M. J. S. (1985). The Meaning of Fossils: Episodes in the History of Palaeontology. University of Chicago Press. p. 24. ISBN 0-226-73103-0 
  8. ^ da Vinci, Leonardo (1938/1956). The Notebooks of Leonardo Da Vinci. London: Reynal & Hitchcock. p. 335. ISBN (OCLC) 67650193. http://books.google.com/?id=qMoQAAAAIAAJ&q=%22If+the+Deluge+had+carried%22&dq=%22If+the+Deluge+had+carried%22. 
  9. ^ Georges Cuvier—Fossil discoveries
  10. ^ Darwin, C (1859) On the Origin of Species. Chapter 10: On the Imperfection of the Geological Record.
  11. ^ Schopf JW (1999) Cradle of Life: The Discovery of the Earth's Earliest Fossils, Princeton University Press, Princeton, NJ.
  12. ^ "The Virtual Fossil Museum - Fossils Across Geological Time and Evolution". http://www.fossilmuseum.net/. Retrieved 2007-03-04. 
  13. ^ Knoll, A, (2003) Life on a Young Planet. (Princeton University Press, Princeton, NJ)
  14. ^ Paul CRC and Donovan SK, (1998) An overview of the completeness of the fossil record. in The Adequacy of the Fossil Record (Paul CRC and Donovan SK eds). 111–131 (John Wiley, New York).
  15. ^ Fortey R, Trilobite!: Eyewitness to Evolution. Alfred A. Knopf, New York, 2000.
  16. ^ Donoghue, PCJ, Bengtson, S, Dong, X, Gostling NJ, Huldtgren, T, Cunningham, JA, Yin, C, Yue, Z, Peng, F and Stampanoni, M (2006) Synchrotron X-ray tomographic microscopy of fossil embryos. Nature 442, 680–683
  17. ^ Shute, C. H. and Cleal, C. J. (1986) Palaeobotany in museums. Geological Curator, 4, 553–559
  18. ^ Palmer, T. J., and Wilson, MA (1988) Parasitism of Ordovician bryozoans and the origin of pseudoborings. Palaeontology 31, 939–949
  19. ^ a b Taylor, P. D. (1990) Preservation of soft-bodied and other organisms by bioimmuration: A review. Palaeontology 33, 1–17
  20. ^ Wilson, MA, Palmer, T. J. and Taylor, P. D. (1994) Earliest preservation of soft-bodied fossils by epibiont bioimmuration: Upper Ordovician of Kentucky. Lethaia 27, 269–270
  21. ^ "Stromatolites, the Oldest Fossils". http://www.fossilmuseum.net/Tree_of_Life/Stromatolites.htm. Retrieved 2007-03-04. 
  22. ^ Knoll, A. H., Barghorn, E. S., Awramik, S. M. (1978). New organisms from the Aphebian Gunflint Iron Formation. Journal of Paleontology(52), 1074–1082.
  23. ^ Lowe, D. R. (1994). Abiological origin of described stromatolites older than 3.2 Ga. Geology, 22, 387–390
  24. ^ "coprolites - Definitions from Dictionary.com". http://dictionary.reference.com/search?q=coprolites. 
  25. ^ Herron, Scott Freeman, Jon C. (2004). Evolutionary analysis (3rd ed. ed.). Upper Saddle River, NJ: Pearson Education. pp. 816. ISBN 978-0-13-101859-4. 
  26. ^ Derived fossil
  27. ^ "Reworked fossil" in Glossary of Geology
  28. ^ Ed Strauss (2001). "Petrified Wood from Western Washington". http://www.edstrauss.com/pwoodfx.html. Retrieved April 8, 2011. 
  29. ^ 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. http://books.google.com/books?id=Fhm-oed74JgC&dq=naming+fossil+wood&source=gbs_navlinks_s. 
  30. ^ Milmo, Cahal (2009-11-25). "Fossil theft: One of our dinosaurs is missing". The Independent (London). http://www.independent.co.uk/news/science/fossil-theft-one-of-our-dinosaurs-is-missing-1826931.html. Retrieved 2010-05-02. 
  31. ^ Simons, Lewis. "Fossil Wars". National Geographic. The National Geographic Society. http://science.nationalgeographic.com/science/prehistoric-world/fossil-wars.html. 
  32. ^ Willis, Paul; Clark, Tim; Dennis, Carina (18 April 2002). "Fossil Trade". Catalyst. http://www.abc.net.au/catalyst/stories/s532586.htm. 
  33. ^ Farrar, Steve (5 November 1999). "Cretaceous crimes that fuel the fossil trade". Times Higher Education. http://www.timeshighereducation.co.uk/story.asp?storyCode=148688&sectioncode=26. Retrieved 2 November 2011. 
  34. ^ http://www.globaltimes.cn/www/english/language/bilingual/2009-11/483395.html[dead link]

Further reading

External links

   
               

 

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