Editing Fossil (section)

== History of study ==
{{Main|History of paleontology}}
{{For timeline|Timeline of paleontology}}

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 [[Timeline of evolution|history of life on Earth]]. [[Paleontologist]]s examine the fossil record to understand the process of evolution and the way particular [[species]] have evolved.

=== Ancient civilizations ===
[[File:hyperborean-gryphon-persepolis-protoceratops-psittacosaurus-skeletons.jpg|thumb|right|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 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 [[echinoderm]]s set precisely at the hand grip, dating back to ''[[Homo heidelbergensis]]'' and [[Neanderthal]]s.<ref name=prehistoric /> 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 (deity)|Set]] was associated with the [[hippopotamus]], therefore fossilized bones of hippo-like species were kept in that deity's temples.<ref>{{Cite web |url=http://www.wondersandmarvels.com/2016/09/ancient-egyptians-collected-fossils.html |title=Ancient Egyptians Collected Fossils |access-date=9 February 2019 |archive-url=https://web.archive.org/web/20190210044430/http://www.wondersandmarvels.com/2016/09/ancient-egyptians-collected-fossils.html |archive-date=10 February 2019 |url-status=dead |date=5 September 2016 }}</ref> Five-rayed fossil sea urchin shells were associated with the deity [[Sopdu]], the Morning Star, equivalent of [[Venus (mythology)|Venus]] in Roman mythology.<ref name=prehistoric />

[[File:Micraster coranguinum.4 - Cretacico superior.JPG|thumb|right|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.]]
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 [[gryphon]]s protected golden treasure. There was indeed gold mining [[Dzungarian Gate#Hyperborean connection|in that approximate region]], where beaked ''[[Protoceratops]]'' skulls were common as fossils.

A later [[Ancient Greece|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 [[vapor]]ous [[exhalation]]s,<ref>{{Cite book|via=The Internet Classics Archive | title=[[Meteorology (Aristotle)|Meteorology]]
| author=Aristotle
| author-link=Aristotle
| translator= E. W. Webster
| orig-year = 350 {{sc|BCE}}
 | year = 1931
| chapter = Book {{sc|iii}} part 6
|chapter-url=http://classics.mit.edu/Aristotle/meteorology.3.iii.html|access-date=2023-02-20|archive-date=18 February 2014|archive-url=https://web.archive.org/web/20140218151153/http://classics.mit.edu/Aristotle/meteorology.3.iii.html|url-status=live}}</ref> which [[Persia]]n polymath [[Avicenna]] modified into the theory of [[Petrifaction|petrifying]] [[fluid]]s ({{lang|la|succus lapidificatus}}). Recognition of fossil seashells as originating in the sea was built upon in the 14th century by [[Albert of Saxony (philosopher)|Albert of Saxony]], and accepted in some form by most [[naturalist]]s by the 16th century.<ref>{{Cite book|title=The Meaning of Fossils: Episodes in the History of Palaeontology|first=M. J. S.|last=Rudwick|year=1985|publisher=[[University of Chicago Press]]|url=https://books.google.com/books?id=-NuYXr8BszwC&pg=PA24|isbn=978-0-226-73103-2|page=24|access-date=11 October 2018|archive-date=17 March 2023|archive-url=https://web.archive.org/web/20230317062708/https://books.google.com/books?id=-NuYXr8BszwC&pg=PA24|url-status=live}}</ref>

Roman naturalist [[Pliny the Elder]] wrote of "[[tongue stone]]s", which he called [[glossopetra]]. These were fossil shark teeth, thought by some classical cultures to look like the tongues of people or snakes.<ref name=sharkteeth /> He also wrote about the [[horns of Ammon]], which are fossil [[ammonite]]s, whence the group of shelled octopus-cousins ultimately draws its modern name. Pliny also makes one of the earlier known references to [[toadstone]]s, 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.<ref>{{Cite web |url=http://www.gwydir.demon.co.uk/jo/fossils/pliny.htm |title=References to fossils by Pliny the Elder |access-date=16 February 2019 |archive-url=https://web.archive.org/web/20190102155131/http://gwydir.demon.co.uk/jo/fossils/pliny.htm |archive-date=2 January 2019 |url-status=dead }}</ref>

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 (mythology)|thunderbird]].<ref>{{Cite book|url=https://books.google.com/books?id=jb9dAQAAQBAJ&q=fossil+legends+of+the+first+americans|title=Fossil Legends of the First Americans|first=Adrienne|last=Mayor|date=24 October 2013|publisher=Princeton University Press|access-date=18 October 2019|via=Google Books|isbn=978-1-4008-4931-4|archive-date=17 March 2023|archive-url=https://web.archive.org/web/20230317062708/https://books.google.com/books?id=jb9dAQAAQBAJ&q=fossil+legends+of+the+first+americans|url-status=live}}</ref>

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.<ref>{{Cite web |url=http://theconversation.com/how-we-know-that-ancient-african-people-valued-fossils-and-rocks-110321 |title=How we know that ancient African people valued fossils and rocks |date=29 January 2019 |access-date=9 February 2019 |archive-url=https://web.archive.org/web/20190210152607/http://theconversation.com/how-we-know-that-ancient-african-people-valued-fossils-and-rocks-110321 |archive-date=10 February 2019 |url-status=live }}</ref>

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.<ref name=sharkteeth>{{Cite web |url=http://www.gwydir.demon.co.uk/jo/fossils/cartilage.htm |title=Cartilaginous fish |access-date=16 February 2019 |archive-url=https://web.archive.org/web/20170730044544/http://gwydir.demon.co.uk/jo/fossils/cartilage.htm |archive-date=30 July 2017 |url-status=dead }}</ref>

In medieval China, the fossil bones of ancient mammals including ''[[Homo erectus]]'' were often mistaken for "[[dragon]] bones" and used as medicine and [[aphrodisiac]]s. 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.<ref>{{cite news |url=http://culture.people.com.cn/BIG5/n/2013/0517/c22219-21521301.html |title=4億年前"書法化石"展出 黃庭堅曾刻下四行詩[圖] |trans-title=400 million-year-old fossil appeared in exhibition with poem by Huang Tingjian |date=17 May 2013 |access-date=7 June 2018 |newspaper=[[People's Daily|People's Daily Net]] |language=zh-hant |archive-url=https://web.archive.org/web/20180612141515/http://culture.people.com.cn/BIG5/n/2013/0517/c22219-21521301.html |archive-date=12 June 2018 |url-status=live }}</ref> In his ''[[Dream Pool Essays]]'' published in 1088, Song dynasty Chinese [[scholar-official]] [[Shen Kuo]] hypothesized that marine fossils found in a [[stratum|geological stratum]] of mountains located hundreds of miles from the [[Pacific Ocean]] was evidence that a prehistoric seashore had once existed there and [[Geomorphology|shifted over centuries of time]].<ref>Sivin, Nathan (1995). ''Science in Ancient China: Researches and Reflections''. Brookfield, Vermont: VARIORUM, Ashgate Publishing. III, p. 23</ref><ref name=nj>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.</ref> His observation of [[petrified]] [[bamboo]]s 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 (general concept)|climate change]] due to bamboo naturally growing in wetter climate areas.<ref name=nj /><ref>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}}.</ref><ref name="Rafferty 2012 p. 6">Rafferty, John P. (2012). ''Geological Sciences; Geology: Landforms, Minerals, and Rocks''. New York: Britannica Educational Publishing, p. 6. {{ISBN|9781615305445}}</ref>

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 [[List of ancient Greek philosophers|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.<ref>Desmond, Adrian. "The Discovery of Marine Transgressions and the Explanation of Fossils in Antiquity", ''American Journal of Science'', 1975, Volume 275: 692–707.</ref><ref name="Rafferty 2012 pp 5–6">Rafferty, John P. (2012). ''Geological Sciences; Geology: Landforms, Minerals, and Rocks''. New York: Britannica Educational Publishing, pp. 5–6. {{ISBN|9781615305445}}.</ref>

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

{{blockquote|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.<ref>{{cite book|title=Science, optics, and music in medieval and early modern thought|author=Alistair Cameron Crombie|publisher=Continuum International Publishing Group|year=1990|url=https://books.google.com/books?id=zWrH7h9jNgUC&pg=PA108|isbn=978-0-907628-79-8|pages=108–109|access-date=11 October 2018|archive-date=17 March 2023|archive-url=https://web.archive.org/web/20230317062732/https://books.google.com/books?id=zWrH7h9jNgUC&pg=PA108|url-status=live}}</ref>}}

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.<ref>{{Cite web |url=https://www.nationalgeographic.com/science/2003/02/news-deinotherium-fossils-crete-mythology-paleontology/ |title=Cyclops Myth Spurred by 'One-Eyed' Fossils? |website=[[National Geographic Society]] |access-date=16 February 2019 |archive-url=https://web.archive.org/web/20190217030312/https://www.nationalgeographic.com/science/2003/02/news-deinotherium-fossils-crete-mythology-paleontology/ |archive-date=17 February 2019 |url-status=dead |date=5 February 2003 }}</ref><ref>{{Cite web |url=http://mentalfloss.com/article/64093/8-types-imaginary-creatures-discovered-fossils |title=8 Types of Imaginary Creatures "Discovered" In Fossils |access-date=16 February 2019 |archive-url=https://web.archive.org/web/20190216044433/http://mentalfloss.com/article/64093/8-types-imaginary-creatures-discovered-fossils |archive-date=16 February 2019 |url-status=dead |date=19 May 2015 }}</ref> 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.

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 [[Thunderstone (folklore)#Fossils as thunderstones|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.<ref name=prehistoric>{{Cite web |url=https://www.geolsoc.org.uk/Geoscientist/Archive/June-2012/Prehistoric-fossil-collectors |title=Prehistoric Fossil Collectors |access-date=16 February 2019 |archive-url=https://web.archive.org/web/20190217090444/https://www.geolsoc.org.uk/Geoscientist/Archive/June-2012/Prehistoric-fossil-collectors |archive-date=17 February 2019 |url-status=live }}</ref>

These grew into the [[shepherd's crown]]s of English folklore, used for decoration and as good luck charms, placed by the doorway of homes and churches.<ref name=echinoderm>{{Cite web |url=https://depositsmag.com/2017/04/04/folklore-of-fossil-echinoderms/ |title=Folklore of Fossil Echinoderms |access-date=16 February 2019 |archive-url=https://web.archive.org/web/20190217142211/https://depositsmag.com/2017/04/04/folklore-of-fossil-echinoderms/ |archive-date=17 February 2019 |url-status=live |date=4 April 2017 }}</ref> In [[Suffolk]], a different species was used as a good-luck charm by bakers, who referred to them as [[fairy loaf|fairy loaves]], associating them with the similarly shaped loaves of bread they baked.<ref>{{Cite journal |url=http://sp.lyellcollection.org/content/273/1/279 |title=Shepherds' crowns, fairy loaves and thunderstones: the mythology of fossil echinoids in England |journal=Geological Society, London, Special Publications |volume=273 |issue=1 |pages=279–294 |access-date=16 February 2019 |archive-url=https://web.archive.org/web/20190221225625/http://sp.lyellcollection.org/content/273/1/279 |archive-date=21 February 2019 |url-status=dead |doi=10.1144/GSL.SP.2007.273.01.22 |year=2007 |last1=McNamara |first1=Kenneth J. |bibcode=2007GSLSP.273..279M |s2cid=129384807 }}</ref><ref>{{Cite web |url=http://echinoblog.blogspot.com/2009/01/archaeological-echinoderm-fairy-loaves.html |title=Archaeological Echinoderm! Fairy Loaves & Thunderstones! |access-date=16 February 2019 |archive-url=https://web.archive.org/web/20190217084856/http://echinoblog.blogspot.com/2009/01/archaeological-echinoderm-fairy-loaves.html |archive-date=17 February 2019 |url-status=dead |date=12 January 2009 }}</ref>

=== Early modern explanations ===
[[File:Anoplotherium 1812 Skeleton Sketch.jpg|thumb|Georges Cuvier's 1812 skeletal reconstruction of ''[[Anoplotherium]] commune'' based on fossil remains of the extinct [[artiodactyl]] from [[Montmartre]] in Paris, France]]
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.<ref>{{ cite journal
| title= Leonardo da Vinci, the founding father of ichnoogy
| first = Andrea | last = Baucon
| journal = PALAIOS
| volume = 25 | number= 5/6 
| date = 2010
| pages = 361–367
| publisher = SEPM Society for Sedimentary Geology
| doi = 10.2110/palo.2009.p09-049r | jstor=40606506
| bibcode = 2010Palai..25..361B | s2cid = 86011122 }}</ref>{{rp|361}} For example, Leonardo noticed discrepancies with the biblical flood narrative as an explanation for fossil origins:

{{blockquote|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.}}

{{blockquote|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....<ref>{{cite book | last =da Vinci | first =Leonardo | author-link =Leonardo da Vinci | title =The Notebooks of Leonardo da Vinci | publisher =Reynal & Hitchcock | date =1956 | orig-year =1938 | location =London | page =335 | url ={{google books |plainurl=y |id=qMoQAAAAIAAJ|page335}} | isbn =978-0-9737837-3-5 }}{{Dead link|date=September 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>}}

[[File:Rozprawa o přewratech kůry zemnj, Ichthyosaurus and Plesiosaurus.jpg|thumb|upright=1.2|''[[Ichthyosaurus]]'' and ''[[Plesiosaurus]]'' from the 1834 Czech edition of [[Georges Cuvier|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.<ref name=sharkteeth />

[[Robert Hooke]] (1635–1703) included [[micrograph]]s of fossils in his ''[[Micrographia]]'' and was among the first to observe fossil [[foram]]s. 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.<ref>{{Cite news |url=https://blogs.scientificamerican.com/history-of-geology/july-2-1635-robert-hooke-the-last-virtuoso-of-silly-science/ |title=July 18, 1635: Robert Hooke – The Last Virtuoso of Silly Science |last=Bressan |first=David |work=Scientific American Blog Network |access-date=11 February 2018 |language=en |archive-url=https://web.archive.org/web/20180212142108/https://blogs.scientificamerican.com/history-of-geology/july-2-1635-robert-hooke-the-last-virtuoso-of-silly-science/ |archive-date=12 February 2018 |url-status=dead }}</ref>

[[William Smith (geologist)|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:

{{blockquote|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.<ref>{{cite web|url=http://palaeo.gly.bris.ac.uk/Palaeofiles/History/cuvier.xhtml|title=Cuvier|website=palaeo.gly.bris.ac.uk|access-date=3 November 2008|archive-url=https://web.archive.org/web/20140525001629/http://palaeo.gly.bris.ac.uk/palaeofiles/history/cuvier.xhtml|archive-date=25 May 2014|url-status=dead}}</ref>}}

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.<ref>{{cite web |title=Mary Anning |url=http://www.lymeregismuseum.co.uk/collection/mary-anning/ |website=Lyme Regis Museum |access-date=21 August 2018 |archive-url=https://web.archive.org/web/20180822051829/http://www.lymeregismuseum.co.uk/collection/mary-anning/ |archive-date=22 August 2018 |url-status=dead }}</ref>

=== Linnaeus and Darwin ===
Early [[natural science|naturalists]] well understood the similarities and differences of living species leading [[Carl Linnaeus|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|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&nbsp;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. [[phylum|phyla]]) in the oldest known Cambrian fossiliferous strata.<ref>{{Citation|last=Darwin|first=Charles|chapter=[[:s:The Origin of Species (1872)/Chapter X|Chapter X: On the Imperfection of the Geological Record]]|title=[[On the Origin of Species|The Origin of Species]]
| author-link= Charles Darwin
| year = 1872
| place= London| publisher= John Murray
}}</ref>

=== After Darwin ===
Since Darwin's time, the fossil record has been extended to between 2.3 and 3.5&nbsp;billion years.<ref>Schopf JW (1999) Cradle of Life: The Discovery of the Earth's Earliest Fossils, Princeton University Press, Princeton, NJ.</ref> Most of these Precambrian fossils are microscopic bacteria or [[micropaleontology|microfossils]]. However, macroscopic fossils are now known from the late Proterozoic. The [[Ediacara biota]] (also called Vendian biota) dating from 575&nbsp;million years ago collectively constitutes a richly diverse assembly of early multicellular [[eukaryote]]s.

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 dating|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 [[stratigraphy|stratigraphers]].

Since the early years of the twentieth century, [[absolute dating]] methods, such as [[radiometric dating]] (including [[K–Ar dating|potassium/argon]], [[Argon–argon dating|argon/argon]], [[uranium–lead dating|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&nbsp;billion years old.

=== Modern era ===
{{Quote box
|quote = The fossil record is life's evolutionary epic that unfolded over four&nbsp;billion years as environmental conditions and genetic potential interacted in accordance with natural selection.|source = The Virtual Fossil Museum<ref>{{cite web| url=http://www.fossilmuseum.net/| title=The Virtual Fossil Museum – Fossils Across Geological Time and Evolution| access-date=4 March 2007| archive-url=https://web.archive.org/web/20070308145410/http://www.fossilmuseum.net/| archive-date=8 March 2007| url-status=live}}</ref>|width = 40%|bgcolor =}}

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."<ref>Knoll, A, (2003) Life on a Young Planet. (Princeton University Press, Princeton, NJ)</ref> 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.<ref>{{cite book |editor=Donovan, S. K.|editor2=Paul, C. R. C.|date= 1998 |chapter=An Overview of the Completeness of the Fossil Record |title=The Adequacy of the Fossil Record |pages=111–131 |publisher=Wiley |location= New York |isbn=978-0-471-96988-4}}</ref>

[[File:Eldredgeops-rana-crassituberculata.jpg|thumb|[[Phacopid]] [[trilobite]] ''Eldredgeops rana crassituberculata''. The genus is named after [[Niles Eldredge]]]]

[[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]].<ref>[[Fortey, Richard]], ''Trilobite!: Eyewitness to Evolution''. Alfred A. Knopf, New York, 2000.</ref> 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]] [[Tomography|tomographic]] analysis of early Cambrian bilaterian [[embryo]]nic microfossils yielded new insights of [[Animal|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 [[Diagenesis|diagenetic]] phosphatization resulting in exquisite preservation, including cell structures.{{Technical inline|date=May 2021}} 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]], [[Nematode|Nematoda]] and [[Arthropod]]a.<ref>{{cite journal | last1 = Donoghue | first1 = PCJ | last2 = Bengtson | first2 = S | last3 = Dong | first3 = X | last4 = Gostling | first4 = NJ | last5 = Huldtgren | first5 = T | last6 = Cunningham | first6 = JA | last7 = Yin | first7 = C | last8 = Yue | first8 = Z | last9 = Peng | first9 = F | year = 2006 | title = Synchrotron X-ray tomographic microscopy of fossil embryos | journal = Nature | volume = 442 | issue = 7103| pages = 680–683 | doi=10.1038/nature04890| pmid = 16900198 |display-authors= etal | bibcode = 2006Natur.442..680D | s2cid = 4411929 }}</ref>{{Technical inline|date=May 2021}}

Despite significant advances in uncovering and identifying paleontological specimens, it is generally accepted that the fossil record is vastly incomplete.<ref name="foote1999">{{cite journal | last1 = Foote | first1 = M. | last2 = Sepkoski | first2 = J.J. Jr | title = Absolute measures of the completeness of the fossil record | date = 1999 | journal = Nature | volume = 398 | issue = 6726 | pages = 415–417 | doi = 10.1038/18872| pmid = 11536900 | bibcode = 1999Natur.398..415F | s2cid = 4323702 }}</ref><ref name="benton2009">{{cite journal | last = Benton | first = M. | date = 2009 | title = The completeness of the fossil record | journal = Significance | volume = 6 | issue = 3 | pages = 117–121 | doi = 10.1111/j.1740-9713.2009.00374.x| s2cid = 84441170 | doi-access = free }}</ref> Approaches for measuring the completeness of the fossil record have been developed for numerous subsets of species, including those grouped taxonomically,<ref name="zliobaite2021">{{cite journal | last1 = Žliobaitė | first1 = I. | last2 = Fortelius | first2 = M. | date = 2021 | title = On calibrating the completometer for the mammalian fossil record | journal = Paleobiology | volume = 48 | pages = 1–11 | doi = 10.1017/pab.2021.22| s2cid = 238686414 | doi-access = free }}</ref><ref name="eiting2009">{{cite journal | last1 = Eiting | first1 = T.P. | last2 = Gunnell | first2 = G.G | title = Global Completeness of the Bat Fossil Record | journal = Journal of Mammalian Evolution | date = 2009 | volume = 16 | issue = 3 | pages = 151–173 | doi = 10.1007/s10914-009-9118-x| s2cid = 5923450 }}</ref> temporally,<ref name="brocklehurst2012">{{cite journal | title = The Completeness of the Fossil Record of Mesozoic Birds: Implications for Early Avian Evolution | last1 = Brocklehurst | first1 = N. | last2 = Upchurch | first2 = P. | last3 = Mannion | first3 = P.D. | last4 = O'Connor | first4 = J. | journal = PLOS ONE| date = 2012 | volume = 7 | issue = 6 | page = e39056 | doi = 10.1371/journal.pone.0039056| pmid = 22761723 | pmc = 3382576 | bibcode = 2012PLoSO...739056B | doi-access = free }}</ref> environmentally/geographically,<ref name="retallack1984">{{cite journal | title = Completeness of the rock and fossil record: some estimates using fossil soils | last = Retallack | first = G. | journal = Paleobiology | volume = 10 | issue = 1 | date = 1984 | pages = 59–78 | doi = 10.1017/S0094837300008022| bibcode = 1984Pbio...10...59R | s2cid = 140168970 }}</ref> or in sum.<ref name="benton1994">{{cite journal | last1 = Benton | first1 = M.J. | last2 = Storrs | first2 = G.Wm. | title = Testing the quality of the fossil record: Paleontological knowledge is improving | journal = Geology | date = 1994 | volume = 22 | number = 2 | pages = 111–114 | doi = 10.1130/0091-7613(1994)022<0111:TTQOTF>2.3.CO;2| bibcode = 1994Geo....22..111B }}</ref><ref name="holland1999">{{cite journal | last1 = Holland | first1 = S.M. | last2 = Patzkowsky | first2 = M.E. | date = 1999 | volume = 27 | number = 6 | pages = 491–494 | doi = 10.1130/0091-7613(1999)027<0491:MFSTFR>2.3.CO;2 | title = Models for simulating the fossil record| journal = Geology | bibcode = 1999Geo....27..491H }}</ref> This encompasses the subfield of [[taphonomy]] and the study of biases in the paleontological record.<ref name="koch1978">{{cite journal | last = Koch | first = C. | title = Bias in the published fossil record | journal = Paleobiology | volume = 4 | number = 3 | pages = 367–372 | doi = 10.1017/S0094837300006060 | date = 1978| bibcode = 1978Pbio....4..367K | s2cid = 87368101 }}</ref><ref name="signor1982">{{cite book | last1 = Signore | first1 = P.W. III | last2 = Lipps | first2 = J.H. | chapter = Sampling bias, gradual extinction patterns and catastrophes in the fossil record | title = Geological Implications of Impacts of Large Asteroids and Comets on the Earth | series = Geological Society of America Special Papers | year = 1982 | volume = 190 | editor-last1 = Silver | editor-first1 = L.T. | editor-last2 = Schultz | editor-first2 = P.H. | pages = 291–296 | doi = 10.1130/SPE190-p291| isbn = 0-8137-2190-3 }}</ref><ref name="vilhena2013">{{cite journal | last1 = Vilhena | first1 = D.A. | last2 = Smith | first2 = A.B. | title = Spatial Bias in the Marine Fossil Record | journal = PLOS ONE| volume = 8 | number = 10 | page = e74470 | doi = 10.1371/journal.pone.0074470 | date = 2013| pmid = 24204570 | pmc = 3813679 | bibcode = 2013PLoSO...874470V | doi-access = free }}</ref>