Fossils (from Latin fossus, literally "having been dug up") are the preserved remains or traces of animals, plants, and other organisms from the remote past. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Trace fossils, also called ichnofossils (ˈɪknoʊfɒsɨl ιχνος or ikhnos meaning "trace" or "track" are geological records of biological 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. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) In Geology and related fields a stratum (plural strata) is a layer of rock or Soil with internally consistent characteristics that distinguishes 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. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other eVolution is the third Album by eLDee, it was due to be released in 2008 A taxon (plural taxa) or taxonomic unit, is a name designating an organism or a group of Organisms In Biological nomenclature according to Palaeontology redirects here For the Scientific journal, see Palaeontology (journal.
Fossils are typically distinguished by 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 several billion years old. The Holocene is a Geological epoch which began approximately 10000 years ago (about 8000 BC 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. Radiometric dating (often called radioactive dating) is a technique used to date materials usually based on a comparison between the observed abundance of a naturally occurring
Like extant organisms, fossils vary in size from microscopic, such as single bacterial cells [2] only one micrometer in diameter, to gigantic, such as dinosaurs and trees many meters long and weighing many tons. A microscope ( Greek: ( micron) = small + ( skopein) = to look or see is an instrument for viewing objects that are A micrometer (mаɪˈkrɒmɪtər ( enPR: mī-krŏmʹĭ-tər sometimes known as a micrometer screw gauge is a device used widely in Mechanical engineering 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 exoskeletons of invertebrates. Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine An exoskeleton is an external Skeleton that supports and protects an animal's body in contrast to the internal Endoskeleton of for example a Human. An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate Preservation of soft tissues is exquisitely 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. Feces, faeces, or fæces (see spelling differences) is a waste product from an animal's digestive tract expelled through the Anus A Coprolite is Fossilized animal dung Coprolites are classified as trace fossils as opposed to body fossils as they give evidence for the animal's behaviour (in Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers These types of fossil are called trace fossils (or ichnofossils), as opposed to body fossils. Trace fossils, also called ichnofossils (ˈɪknoʊfɒsɨl ιχνος or ikhnos meaning "trace" or "track" are geological records of biological 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. Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as
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Places of exceptional fossilization
Fossil sites with exceptional preservation — sometimes including preserved soft tissues — are known as Lagerstätten. A Lagerstätte ( German; literally place of storage; plural Lagerstätten) is a sedimentary deposit that exhibits extraordinary fossil These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying decomposition. For other uses of the term "hypoxia" see Hypoxia. Hypoxia or oxygen depletion is a phenomenon that occurs in aquatic environments Lagerstätten span geological time from the Cambrian period to the present. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with The Holocene is a Geological epoch which began approximately 10000 years ago (about 8000 BC 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. The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with In the Maotianshan shales is a lower Cambrian Konservat Lagerstätte named for Maotianshan Hill ( in Chengjiang County Yunnan Province See also Burgess shale type fauna The Burgess Shale is famous for the exceptional preservation of the fossils found within it in which the soft parts are preserved The Devonian is a geologic period and system of the Paleozoic era spanning from to million years ago. The Hunsrück Slate (Hunsrückschiefer is a Devonian Lagerstätte famous for exceptional preservation of a highly diverse Fossil fauna assemblage The Jurassic is a geologic period and system that extends from about Ma (million years ago to Ma that is from the end of the Triassic to the beginning The Solnhofen limestone is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of Fossilized organisms some of which such as sea jellies The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 The Mazon Creek fossils are conservation Lagerstätten found near Morris, in Grundy County Illinois.
Earliest fossiliferous sites
Earth’s oldest fossils are the stromatolites consisting of rock built from layer upon layer of sediment and precipitants. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. Stromatolites (from Greek στρώμα strōma, mattress bed stratum and λιθος lithos, rock are layered accretionary Structures formed in Stromatolites (from Greek στρώμα strōma, mattress bed stratum and λιθος lithos, rock are layered accretionary Structures formed in Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of [3] 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. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually 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 Archaean eon. In Biology, abiotic components are non-living Chemical and Physical factors in the environment.
It is most widely accepted that stromatolites from the late Archaean 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. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. This article is about a type of political territory For other uses see Colony (disambiguation. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. Banded iron formations (also known as banded ironstone formations or BIF s are a distinctive type of rock often found in primordial ( Precambrian) Sedimentary
Even though it is extra rare, microstructures resembling cells are sometimes found within stromatolites; but these are also the source of scientific contention. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called The Gunflint Chert contains abundant microfossils widely accepted as a diverse consortium of 2. The Gunflint chert (188 Ga) is a sequence of Banded iron formation rocks that are exposed in the Gunflint Range of northern Minnesota and western Micropaleontology (also sometimes spelled as micropalaeontology) is that branch of Paleontology which studies microfossils 0 bya microbes. In Astronomy, Geology, and Paleontology, bya or " bya " is an Acronym for billion years ago. A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually [4]
In contrast, putative fossil cyanobacteria cells from the 3. 4 bya Warrawoona Group in Western Australia are in dispute since abiotic processes cannot be ruled out. [5] 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 (reference). In the Natural sciences, Abiogenesis, or origin of life, is the study of how Life on Earth emerged from Inanimate Organic eVolution is the third Album by eLDee, it was due to be released in 2008 The continued study of these oldest fossils is paramount to calibrate complementary molecular phylogenetics models. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by
Developments in interpretation of the fossil record
- See also: History of paleontology
Ever since recorded history began, and probably before, people have found fossils, pieces of rock and minerals which have replaced the remains of biologic organisms or preserved their external form. The history of Paleontology traces the effort to understand the history of life on Earth by studying the Fossil record left behind by living organisms History is the study of the past particularly the written record Those who study history as a Profession are called Historians Etymology In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific These fossils, and the totality of their occurrence within the sequence of Earth's rock strata is referred to as the fossil record. In Geology and related fields a stratum (plural strata) is a layer of rock or Soil with internally consistent characteristics that distinguishes
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. eVolution is the third Album by eLDee, it was due to be released in 2008 This timeline of the evolution of life outlines the major events in the development Paleontologists examine the fossil record in order to understand the process of evolution and the way particular species have evolved. Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank.
Explanations
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. Homo erectus ( Latin: "upright man" is an extinct species of the genus Homo, believed to have been the first hominin The dragon is a Legendary creature of which some interpretation or depiction appears in almost every culture worldwide In the West the presence of fossilized sea creatures high up on mountainsides was seen as proof of the biblical deluge. Noah's Ark, according to the Book of Genesis (chapters 6-9 is the story of a large vessel built at God 's command to save Noah, his family More scientific views of fossils began to emerge during the Renaissance. For example, Leonardo Da Vinci noticed discrepancies with the use of the biblical flood narrative as an explanation for fossil origins:
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- "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. Leonardo di ser Piero da Vinci ( April 15 1452 – May 2 1519 was an Italian Polymath, having been a scientist Mathematician, Engineer
- 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. . . "[6]
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. William Smith ( March 23 1769 &ndash August 28 1839) was an English Geologist, credited with creating the first nationwide The law of superposition (or the principle of superposition) is a key axiom based on observations of Natural history that is a foundational principle of sedimentary 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. Charles Robert Darwin (February 12 1809 &ndash April 19 1882 was an English naturalist, who realised and demonstrated that all Species of life 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.
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. In Science, the term natural science refers to a naturalistic approach to the study of the Universe, which is understood as obeying rules or law of Carl Linnaeus (Latinized as Carolus Linnaeus, also known after his ennoblement as, May 23 new style (13 May old style 1707 who laid the foundations for 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.
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. Charles Darwin 's On the Origin of Species (published 24 November 1859) is a seminal work in Scientific literature and arguably the The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with 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. A phylum ( Plural: phyla) is a Taxonomic rank between Kingdom and above Class. [7]
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. [8] Most of these Precambrian fossils are microscopic bacteria or microfossils. Micropaleontology (also sometimes spelled as micropalaeontology) is that branch of Paleontology which studies microfossils However, macroscopic fossils are now known from the late Proterozoic. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The Ediacaran biota (also called Vendian biota) dating from 575 million years ago collectively constitutes a richly diverse assembly of early multicellular eukaryotes. The Ediacara (ˌiːdɪˈækərə formerly Vendian) biota are ancient lifeforms of the Ediacaran Period which represent the earliest known complex Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex
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. Biostratigraphy is the branch of Stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the Fossil assemblages contained For the first 150 years of geology, biostratigraphy and superposition were the only means for determining the relative age of rocks. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit Before the advent of Absolute dating in the 20th century Archaeologists and Geologists were largely limited to the use of relative dating techniques The geologic time scale was developed based on the relative ages of rock strata as determined by the early paleontologists and stratigraphers. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other Stratigraphy, a branch of Geology, studies rock layers and layering ( stratification)
Since the early years of the twentieth century, absolute dating methods, such as radiometric dating (including potassium/argon, argon/argon, uranium series, and carbon-14 dating) have been used to verify the relative ages obtained by fossils and to provide absolute ages for many fossils. Absolute dating is the process of determining a specific date for an archaeological or palaeontological site or artifact Radiometric dating (often called radioactive dating) is a technique used to date materials usually based on a comparison between the observed abundance of a naturally occurring Potassium-argon dating or K-Ar dating is a Radiometric dating method used in Geochronology and Archeology. Uranium-lead is one of the oldest and most refined Radiometric dating schemes with a routine age range of about 1 million years to over 4 Radiocarbon dating is a Radiometric dating method that uses the naturally occurring Radioisotope Carbon-14 (14C to determine the age of Radiometric dating has shown that the earliest known stromatolites are over 3. Stromatolites (from Greek στρώμα strōma, mattress bed stratum and λιθος lithos, rock are layered accretionary Structures formed in 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. In the Natural sciences under the umbrella of Natural history, Geochronology is the Science of determining the absolute age of rocks, Fossils Modern geologists and Geophysicists consider the age of Earth to be around 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. "[9] 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 Archaean is only "recounted by microscopic fossils and subtle chemical signals. "[10] 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. [11]
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. Niles Eldredge (born August 25 1943 is an American paleontologist, who along with Stephen Jay Gould, proposed the theory of Punctuated equilibrium The Devonian is a geologic period and system of the Paleozoic era spanning from to million years ago. [12] 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. Stephen Jay Gould (September 10 1941 &ndash May 20 2002 was a prominent American paleontologist, evolutionary biologist, and historian of science Niles Eldredge (born August 25 1943 is an American paleontologist, who along with Stephen Jay Gould, proposed the theory of Punctuated equilibrium Punctuated equilibrium is a theory of evolutionary biology which states that most sexually reproducing populations experience little change for most of their geological
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. A synchrotron is a particular type of cyclic Particle accelerator in which the magnetic field (to turn the particles so they circulate and the electric field (to accelerate X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Tomography is imaging by sections or sectioning A device used in tomography is called a tomograph, while the image produced is a tomogram. An embryo (from Greek:, plural, lit "that which grows" from en- "in" + bryein "to swell be full" is a multicellular 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. Markuelia is a Genus of Fossil worm-like bilaterian animals allied to Ecdysozoa and known from strata of Lower Cambrian to Lower Ordovician Protostomia (from the Greek: mouth first) are a Taxon of Animals Together with the Deuterostomes and a few smaller phyla A germ layer is a collection of cells formed during animal Embryogenesis. These 543-million-year-old embryos support the emergence of some aspects of arthropod development earlier than previously thought in the late Proterozoic. Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The preserved embryos from China and Siberia underwent rapid diagenetic phosphatization resulting in exquisite preservation, including cell structures. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Siberia (Сиби́рь Sibir) is the name given to the vast region constituting almost all of Northern Asia and for the most part currently serving In Geology and Oceanography, diagenesis is any chemical physical or biological change undergone by a Sediment after its initial deposition and during 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. Priapulida ( priapulid worms or penis worms, from Gr πριάπος priāpos ' Priapus ' + Lat The nematodes or roundworms ( Phylum Nematoda from Greek (nema "thread" + -ode "like" are one of the most common Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " [13]
Rarity of fossils
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. Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of However there are exceptions to this, such as if an organism becomes frozen, desiccated, or comes to rest in an anoxic (oxygen-free) environment. Desiccation is the state of extreme dryness or the process of extreme drying Anoxic sea water is sea water depleted of Oxygen. It is generally found in areas with restricted water exchange Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the 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 lived for a long time. Taphonomy is the study of a decaying Organism over time The term taphonomy (from the Greek taphos - τάφος meaning burial and nomos - 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. Macrofossils (occasionally spelled " macro-fossil " are preserved organic remains large enough to be visible without a Microscope. Micropaleontology (also sometimes spelled as micropalaeontology) is that branch of Paleontology which studies microfossils
Some casual observers have been perplexed by the rarity of transitional species within the fossil record. Transitional fossils are the Fossilized remains of transitional forms of life that illustrate an evolutionary transition 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. Charles Robert Darwin (February 12 1809 &ndash April 19 1882 was an English naturalist, who realised and demonstrated that all Species of life 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. Punctuated equilibrium is a theory of evolutionary biology which states that most sexually reproducing populations experience little change for most of their geological
Types of preservation
Permineralization
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. Trilobites ("three-lobes" are extinct Arthropods that form the class Trilobita. Asaphus kowalewskii is one of the 35 species of Trilobite of the Genus Asaphus (this particular species is sometimes placed in its own 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. The skin is the outer covering of living tissue of an animal (or plant Feathers are one of the epidermal growths that form the distinctive outer covering or Plumage, on Birds They are considered the most complex integumentary structures This is a form of diagenesis. In Geology and Oceanography, diagenesis is any chemical physical or biological change undergone by a Sediment after its initial deposition and during
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 internal mold is formed when sediments or minerals fill the internal cavity of an organism, such as the inside of a bivalve or snail.
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 minerals are still present but in a different crystal form, as from aragonite to calcite. Aragonite is a Carbonate mineral, one of the two common naturally occurring polymorphs of Calcium carbonate, Ca[[carbon C]] O 3 Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3
Compression 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. A compression fossil is a Fossil preserved in Sedimentary rock that has undergone Physical compression. In this case the fossil consists of original material, albeit in a geochemically altered state. This chemical change is an expression of diagenesis. In Geology and Oceanography, diagenesis is any chemical physical or biological change undergone by a Sediment after its initial deposition and during
Bioimmuration
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. [15] Usually it is a sessile skeletal organism, such as a bryozoan or an oyster, which grows along a substrate, covering other sessile encrusters. 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 which grows upwards, preserving the settler in its skeleton. Bioimmuration is known in the fossil record from the Ordovician[16] to the Recent. [17]
To sum up, fossilization processes proceed differently for different kinds of tissues and under different kinds of conditions.
Trace fossils
Trace fossils are the remains of trackways, burrows, bioerosion, eggs and eggshells, nests, droppings and other types of impressions. Trace fossils, also called ichnofossils (ˈɪknoʊfɒsɨl ιχνος or ikhnos meaning "trace" or "track" are geological records of biological Trace fossils, also called ichnofossils (ˈɪknoʊfɒsɨl ιχνος or ikhnos meaning "trace" or "track" are geological records of biological Bioerosion describes the Erosion of hard ocean substrates by living organisms by a number of mechanisms In most Birds and Reptiles an egg ( Latin ovum) is the Zygote, resulting from Fertilization of the Ovum. Fossilized droppings, called coprolites, can give insight into the feeding behavior of animals and can therefore be of great importance. A Coprolite is Fossilized animal dung Coprolites are classified as trace fossils as opposed to body fossils as they give evidence for the animal's behaviour (in
Microfossils
'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. Micropaleontology (also sometimes spelled as micropalaeontology) is that branch of Paleontology which studies microfossils A commonly applied cut-off point between "micro" and "macro" fossils is 1 mm, although this is only an approximate guide. Macrofossils (occasionally spelled " macro-fossil " are preserved organic remains large enough to be visible without a Microscope. 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. The Foraminifera, ("Hole Bearers" or forams for short are a large group of Amoeboid Protists with reticulating Pseudopods fine Coccolithophores (also called coccolithophorids) are single-celled Algae, Protists and Phytoplankton belonging to the Division Palynology is the science that studies contemporary and fossil Palynomorphs including Pollen, Spores, Dinoflagellate Cysts Acritarchs 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. Paleoclimatology (also Palaeoclimatology) is the study of Climate change taken on the scale of the entire History of Earth. Biostratigraphy is the branch of Stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the Fossil assemblages contained
Resin fossils
Fossil resin (colloquially called amber) is a natural polymer found in many types of strata throughout the world, even the Arctic. Mosquitoes are insects in the family Culicidae. They have a pair of scaled wings a pair of Halteres, a slender body and long legs True flies are Insects of the Order Diptera ( Greek: di = two and pteron = wing possessing a single pair of Amber is Fossil tree Resin, which is appreciated for its color and beauty Amber is Fossil tree Resin, which is appreciated for its color and beauty A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds The Arctic is the Region around the Earth 's North Pole, opposite the Antarctic region around the South Pole. The oldest fossil resin dates to the Triassic, though most dates to the Tertiary. The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago The chuprichondira geological time interval covers roughly the time span between the demise of the non- avian Dinosaurs and beginning of the most recent Ice Age, approximately 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. An adaptation is a characteristic of an Organism that has been favored by Natural selection and 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. An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes Preservation of inclusions can be exquisite, including small fragments of DNA. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known
Pseudofossils
Pseudofossils are visual patterns in rocks that are produced by naturally occurring geologic processes rather than biologic processes. Pseudofossils are Inorganic objects markings or impressions that might be mistaken for Fossils Pseudofossils may be misleading as some types of mineral deposits 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. A crystal dendrite is a crystal that develops with a typical multi-branching tree-like form Other types of pseudofossils are kidney ore (round shapes in iron ore) and moss agates, which look like moss or plant leaves. This article is about the semi-precious stone For other uses see Agate (disambiguation. 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. A concretion is a volume of Sedimentary rock in which a Mineral cement fills the porosity (i
Living fossils
Living fossil is an informal term used for any living species which closely resembles a species known from fossils -- that is, it is as if the ancient fossil had "come to life. Living fossil is an informal term for any living Species (or Clade) of organism which appears In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. "
This can be (a) a species or taxon known only from fossils until living representatives were discovered, such as the lobed-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, primoidial 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 group in the fossil record. A taxon (plural taxa) or taxonomic unit, is a name designating an organism or a group of Organisms In Biological nomenclature according to Coelacanth (ˈsiːləkænθ adaptation of Modern Latin Cœlacanthus > cœl-us + acanth-us from Greek κοῖλ-ος + ἄκανθ-α) is the common name for Monoplacophora, meaning “bearing one plate” is a class of shelled Mollusks These organisms were known only from the Fossil record ranging from the Ginkgo is a genus of highly unusual non-flowering plants with one extant species G For the former North American fur-trading district see New Caledonia (Canada, and for the Scottish colony in Panama see Darien scheme. KAGU is a Classical music Radio station run by Gonzaga University in Spokane Washington. The Sunbittern, Eurypyga helias is a Bittern -like Bird of tropical regions of the Americas, and the sole member of the family Stromatolites (from Greek στρώμα strōma, mattress bed stratum and λιθος lithos, rock are layered accretionary Structures formed in Brachiopods (from Latin brachium, arm + New Latin -poda, foot are a small phylum of Benthic Invertebrates Also Nautilus (from Greek ναυτίλος, 'sailor' is the common name of any marine creatures of the Cephalopod family Nautilidae, the sole Psilotum ( whisk fern) is a genus of Fern -like Vascular plants one of two genera in the family Psilotaceae, order The horseshoe crab or Atlantic horseshoe crab ( Limulus polyphemus) is a marine Chelicerate Arthropod. The tuatara is a reptile endemic to New Zealand which though it resembles most lizards is actually part of a distinct lineage order Sphenodontia.
See also
- Bioerosion
- Elvis taxon
- Fossil collecting
- History of paleontology
- Ichnology
- Lazarus taxon
- List of transitional fossils
- List of fossils
- List of fossil sites
- Paleobiology
- Petrification
- Shark teeth
- Taphonomy
- Trace fossil
References
- ^ Frequently Asked Questions about Paleontology. San Diego Natural History Museum
- ^ {{cite journal | last = Westall | first = Frances | coauthors = et al. Bioerosion describes the Erosion of hard ocean substrates by living organisms by a number of mechanisms In Paleontology, an Elvis taxon (plural Elvis taxa) is a Taxon which has been misidentified as having re-emerged in the Fossil record after a Fossil collecting describes the extraction of fossilised material for profit pleasure or scientific study The history of Paleontology traces the effort to understand the history of life on Earth by studying the Fossil record left behind by living organisms Ichnology is the branch of Biology that deals with traces of organismal behavior In Paleontology, a Lazarus taxon (plural taxa) is a Taxon that disappears from one or more periods of the Fossil record, only to appear This is a very tentative list of Transitional fossils (fossil remains of a creature that exhibits primitive traits in comparison with more derived life-forms to which it is related This is a list of notable fossils. Note this does not attempt to be an exhausive list of fossils of which there are millions but those that are of enough significance to merit This is a worldwide list of important and/or well-known localities where Fossils have been found Paleobiology (sometimes spelled palaeobiology) is a growing and comparatively new discipline which combines the methods and findings of the Natural science Biology In Geology, petrifaction or petrification is the process by which Organic material is converted into stone or a similar substance without Shark teeth are relics of Shark Evolution and Biology. Shark skeletons are composed entirely of Cartilage. Taphonomy is the study of a decaying Organism over time The term taphonomy (from the Greek taphos - τάφος meaning burial and nomos - Trace fossils, also called ichnofossils (ˈɪknoʊfɒsɨl ιχνος or ikhnos meaning "trace" or "track" are geological records of biological | title = Early Archean fossil bacteria and biofilms in hydrothermally-influenced sediments from the Barberton greenstone belt, South Africa | journal = Precambrian Research | volume = 106 | issue = 1-2 | pages = 93-116 | url = http://ieg.or.kr:8080/abstractII/E0210601006.html
- ^ Stromatolites, the Oldest Fossils. Retrieved on 2007-03-04. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 51 - Nero, later to become Roman Emperor, is given the title Princeps iuventutis (head of the youth
- ^ Knoll, A. H. , Barghorn, E. S, Awramik, S. M,. (1978). New organisms from the Aphebian Gunflint Iron Formation. Journal of Paleontology(52), 1074-1082.
- ^ Lowe, D. R. (1994). Abiological origin of described stromatolites older than 3. 2 Ga. Geology, 22, 387-390
- ^ da Vinci, Leonardo. Leonardo di ser Piero da Vinci ( April 15 1452 – May 2 1519 was an Italian Polymath, having been a scientist Mathematician, Engineer The Notebooks of Leonardo Da Vinci. Oxford: Oxford University Press, 28-29. ISBN 0-19-283897-0.
- ^ Darwin, C (1859) On the Origin of Species. Chapter 10: On the Imperfection of the Geological Record.
- ^ Schopf JW (1999) Cradle of Life: The Discovery of the Earth's Earliest Fossils, Princeton University Press, Princeton, NJ.
- ^ The Virtual Fossil Museum - Fossils Across Geological Time and Evolution. Retrieved on 2007-03-04. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 51 - Nero, later to become Roman Emperor, is given the title Princeps iuventutis (head of the youth
- ^ Knoll, A, (2003) Life on a Young Planet. (Princeton University Press, Princeton, NJ)
- ^ 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).
- ^ Fortey R, Trilobite!: Eyewitness to Evolution. Alfred A. Knopf, New York, 2000.
- ^ 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
- ^ Palmer, TJ, and Wilson, MA (1988) Parasitism of Ordovician bryozoans and the origin of pseudoborings. Palaeontology 31,939-949
- ^ Taylor, PD. (1990) Preservation of soft-bodied and other organisms by bioimmuration: A review. Palaeontology 33,1-17
- ^ Wilson, MA, Palmer, TJ and Taylor, PD (1994) Earliest preservation of soft-bodied fossils by epibiont bioimmuration: Upper Ordovician of Kentucky. Lethaia 27, 269-270
- ^ Taylor, PD. (1990) Preservation of soft-bodied and other organisms by bioimmuration: A review. Palaeontology 33,1-17
External links
- The Virtual Fossil Museum throughout Time and Evolution
- Paleoportal, geology and fossils of the United States
- Palaeos, a multi-authored wiki encyclopedia on the history of life on Earth
- The Fossil Record, a complete listing of the families, orders, class and phyla found in the fossil record
- Bioerosion website, including fossil record
Dictionary
fossil
-noun
- in paleontology, the mineralized remains of an animal or plant
- (linguistics) a fossilized term
- (metaphorically) anything extremely old, extinct, or outdated
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