Editing Paleontology (section)

==Subdisciplines==
Paleontology overlaps and integrates with many other disciplines of science into fields that focus on more specific topics. The overlap of paleontology with biology, paleobiology, includes studies on macroevolution, extinction, speciation, diversification, morphology, biogeography, phylogeny, paleoecology, molecular paleontology, taphonomy, and [[evolutionary developmental biology]].<ref name="hall2002"/> Many subdisciplines of paleontology are focused on specific groups of organisms: invertebrate paleontology is the study of fossil [[invertebrates]]; vertebrate paleontology is the study of fossil [[vertebrates]];<ref name="hall2002"/> [[paleoalgology]] is the study of fossil algae;<ref name="nitecki1985"/> [[paleobotany]] is the study of fossil plants;<ref name="taylor2009"/> [[paleoentomology]] is the study of fossil [[insects]];<ref name="morgan1980"/> [[paleoherpetology]] is the study of fossil reptiles and [[amphibians]];<ref name="steyer2021"/> [[paleoichthyology]] is the study of fossil [[fish]];<ref name="ricqles2021"/> [[paleomalacology]] is the study of fossil [[mollusks]];<ref name="chaves2014"/> [[paleomammalogy]] is the study of fossil mammals;<ref name="polly2005"/> [[paleomycology]] is the study of fossil [[fungi]];<ref name="taylor2010"/> [[paleomyrmecology]] is the study of fossil [[ants]];<ref name="barden2023"/> [[paleornithology]] is the study of fossil birds;<ref name="wood2015"/> [[paleoprimatology]] is the study of fossil primates;<ref name="simons1972"/> and [[paleozoology]] is the study of fossil animals.<ref name="simpson1943"/> Paleontology in general also overlaps with studies on growth, [[paleoanthropology]], many fields that focus on the Earths climatic and geographic past, [[histology]], ichnology, [[pathology]] and forensics, and taphonomy, forming the subdisciplines described below.<ref name="hall2002"/>

===Paleoanthropology===
{{main|Paleoanthropology}}
[[File:Ghamari cave (2).jpg|thumb|left|Archaeological excavations in the [[Middle Paleolithic]] cave site of the Ghamari Cave in [[Zagros Mountains]]]]
Paleoanthropology is a field of study that focuses on the evolutions of humans. The field can trace its origins to the works of German naturalist [[Johann Blumenbach]] in the late 18th century and then the discovery of a neanderthal in the mid 19th century though it only took its modern form as the study of human evolution following [[World War II]] with the acceptance of evolutionary biology. Paleoanthropology utilizes information on humans drawn from both fossils and [[archaeology]] to interpret the rise and spread of humans. Beliefs were that only a single species of hominid was present at any one time, forming a natural progression to modern humans, considering the diverse groups of species proposed as [[synonyms]]. Discoveries showed that this belief was not correct, with human evolution displaying a complex and uncertain arrangement of individuals, populations, and species with the advent of phylogenetic analyses. ''Ardipithecus'' is one of the oldest known of the human branch of hominids, having lived 4.4 million years ago and only found in 1994. Species of the genus ''Australopithecus'' from across Africa have been named since the 1970s are slightly younger, but already show the bipedal stance of modern humans. From ''Australopithecus'' likely evolved both ''Homo'' and the more robust hominid ''[[Paranthropus]]'', which is unlike modern humans in build but lived alongside early humans for some time.<ref name="tattersall2000"/>

It is known that early humans were capable of making and using tools from the discoveries of fossils of ''[[Homo habilis]]'' in places where stone tools had previously been found. The earliest known stone tools are from around 3.3 million years ago, and while they are often associated with ''Homo'' it is also possible that the coexisting species ''[[Australopithecus garhi]]'' was a toolmaker. There is reluctance to believe that a australopith was capable of making and using tools, but the origins of ''Homo'' are unclear and there is little that can be used to distinguish tool-making from non-tool-making hominids when fossils and tools are not found together. The first humans to show a more slender modern bauplan are those of ''[[Homo ergaster]]'', which is sometimes considered part of African ''[[Homo erectus]]'', from around 1.6 million years ago. Once the modern body form evolved, humans spread far beyond Africa, spreading across [[Eurasia]] from which evolved ''[[Homo heidelbergensis]]'' and ''[[Homo neanderthalensis]]''. Though the diversity of neanderthals is uncertain, sites have been found that show they had a burial culture and a rich technological record. The similarities between ''Homo sapiens'' and these older or coexisting species makes it difficult to determine what made modern humans unique.<ref name="tattersall2000"/>

===Paleobiogeography===
{{main|Paleobiogeography}}
[[File:Snider-Pellegrini Wegener fossil map.svg|thumb|right|Biogeographic distribution of fossils in [[Pangaea]]]]
Paleobiogeography is a very similar field to [[biogeography]] but focuses instead on fossils rather than modern organisms. Both fields work to explain the differences in flora and fauna between different locations, rather than the expectation that regions of similar climate and habitat would house the same organisms. Biogeography relies on [[exploration]], both as an exploratory tool to understand the world, but also the physical act of travelling to different places to observe differences. Paleobiogeography is named with the prefix "paleo" to differentiate in its use of the fossil record to study biogeography, which means that paleobiogeography suffers from the same issues as other paleontological fields regarding the limitations of the fossil record.<ref name="lieberman2000"/> It was established as a geoscience from the recognition and acceptance of the theory of [[continental drift]] that was hinted at by the discoveries of similar fossils on now-distance [[continent]]s during the 19th century.<ref name="ross1999"/> Paleobiogeography involves studying the history of life, but is relevant for the study of evolutionary, geological, and ecological changes as external factors such as biogeography are one of the two drivers of evolution. Ecological processes can be studied that cause speciation or regulate diversity, and these differences across location can be tied to geological processes like plate tectonics and climate change. Modern biogeography has the advantage of being able to study molecular markers and more thoroughly study small spatial and temporal regions creating a better picture of a specific environment. Paleobiogeography on the other hand is capable of studying very long timescales, able to track history beyond just the modern era. Flora and fauna may be affected by small-scale cycles as well as broader effects that cannot be seen on a limited timescale, so paleobiogeography can provide a more complete picture of patterns and processes. Through the fossil record, paleobiogeography can monitor the evolution and coevolution of life on Earth, associating patterns with geological events and over long timescales, working with the field of biogeography to understand biogeographical processes.<ref name="lieberman2000"/>

===Paleobiology===
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[[File:Ice age fauna of northern Spain - Mauricio Antón.jpg|thumb|left|upright=1.25|Restoration of ice age megafauna during the [[Pleistocene]] in northern Spain]]
Paleobiology is the study of the biology of extinct organisms. As a topic it has been around since the beginning it paleontology itself, as fossils are the remains of extinct organisms, but the areas of research covered by paleobiology have changed to capture much more theoretical thinking, studying the biological aspects of paleontology rather than geological topics like stratigraphy. This means there is a particular focus on evolution, adaptation, ecology, function, and behavior in paleobiology, especially of invertebrates which are far more common in the fossil record. Darwin's work on evolution was largely paleobiological in nature, drawing from paleontology, geology and biology, but also pushed paleontology into the background as the incompleteness of the fossil record became a hindrance to advancements in evolution. The first use of "paleobiology" as a word came in [[1893 in paleontology|1893]], but it was the work of [[Othenio Abel]] in the 1910s that established "päleobiologie" as the study of biologically informed paleontology.<ref name="sepkoski2009"/> [[Franz Nopcsa]] is also understood to have been a pioneer of paleobiology, and one of the first paleontologists to use histology and the interpret the paleophysiology of extinct animals.<ref name="weishampel2012"/> Biological questions did not change the field of paleontology greatly until the general transformation of the field in the 1950s and 1960s with new approaches to the fossil record and a differing view on the place of paleontology as a discipline. Paleontology was no longer seen as a subdivision of geology but instead as a field of biology or a field of its own, able to be grounded in theoretical thinking and assessed numerically. Paleontology was suggested to be educated as two separate areas: stratigraphy and paleobiology, with significant overlap and incerconnection. Throughout following decades paleobiology would expand to encompass many theoretical fields related to evolution or extinction, and become a feature of museums and [[universities]] supporting the connection between paleontology and biology.<ref name="sepkoski2009"/>

Many of the fields of paleontology can be seen as part of the study of paleobiology, and paleontologists themselves may be better referred to as paleobiologists. Evolution and paleoecology are large parts of the change towards paleobiology and major areas of study and advancements of the field. Theoretical thinking and analysis of evolution has advanced and improved applications of the fossil record. Studies of taphonomy, evolutionary paleoecology, diversity, behavior, trace fossils, and the paleoenvironment all fall under the breadth of paleoecology.<ref name="kelley2013"/> Paleobiology is able to inform on questions about the life appearances of organisms, their ways of communicating or reproducing, their growth, and how they survived and died out. Effective paleobiology requires knowledge of biological fields (evolution, [[genetics]], [[systematics]], evolutionary developmental biology, biogeography, ecology, [[biochemistry]]), geological fields ([[sedimentology]], stratigraphy, Earth history, isotopes, [[geochemistry]], taphonomy), [[statistics]] and applied math, and often even [[computer science]].<ref name="benton2020-1"/> Findings and studies in biology are relevant and applicable to paleontology, and as a result the findings of paleontology become relevant to biology. The available information to study between the two fields is different, forcing paleontological studies to be more integrated while biological studies are more focused, but this is an opportunity for collaborative work.<ref name="valentine2009"/>

===Paleoclimatology===
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[[File:Earth's average surface temperature over the past 500 million years.png|thumb|right|upright=1.2|Estimated global temperature across the last 500 million years]]
Paleoclimatology is the study of the ancient [[climate]]s, and is a "paleo-science" alongside paleoecology and [[paleoceanography]].<ref name="overpeck1995"/> Studies on the climate before and during the Quaternary, where direct measurements become available, are beginning to converge in scope, but the term "paleoclimatology" remains often restricted to the former. Before the identification and acceptance of plate tectonics, paleoclimatology had been applied from the observation that fossils were sometimes found where the climate was currently not suitable to that organism. Little discussion was had about the changing of the climate beyond the [[Last Glacial Maximum]], so paleoclimatology was restricted to the climate of the Quaternary. Inconsistencies between climate-significant rocks and current geography were not able to be reconciled until plate tectonics demonstrates that [[climate zone]]s were constant but the landmasses beneath them would change. Indicators of the paleoclimate could be found in certain types of rocks, which coupled with reconstructions of the paleogeography showed that climate zones in the past were roughly the same as today, with exceptions. During the time of the supercontinent Pangaea, arid regions were believed to be generally lower in [[latitude]] that at other times in the past, which would be explained by the [[monsoon]]al nature of the continent in the 1970s and the understanding that atmospheric circulation of monsoons also affected the regionality of climates. [[Ocean drilling]] of core samples from the seabed were then used to identify [[isotopes]] that could examine the proportions of [[oxygen]] and [[carbon dioxide]] over time to illustrate the warmth and coldness of ocean waters. In some sense, global paleoclimatology would not be possible without these ocean drilling programs. Numerical modelling of the paleoclimate was employed to further the field, though it struggles with the polar regions and the climate of continental interiors. Further development of paleoclimatology will likely focus on the impact to humans of the alterations to the climate that are occurring, and use information from the past to make predictions about the future.<ref name="parrish2013"/>

===Paleoecology===
{{main|Paleoecology}}
[[File:Dinosaur park formation fauna.png|thumb|left|upright=1.3|Restoration of the paleoenviromnent and fauna of the [[Dinosaur Park Formation]]]]
Paleoecology is a diverse field of paleontology that relates to the reconstruction of lifestyles and [[ecosystems]] of ancient life. While we know much about the evolution of life, less is understood about the interactions and behavior of organisms. The large amount of [[speculation]] involved in paleoecological interpretations means it may be disregarded at times, but a developing use of numerical and statistical techniques allows for quantitative assessments of paleoecological hypotheses. Paleoecology also investigates the long-term changing of ecologies and the balancing of chemical, biological, and physical changes of the world. Fossil animals and plant do not normally preserve in completion or in their undisturbed habitats, with [[scavenging]], erosion, or transportation complicating their interpretation.<ref name="benton2020-4"/> The study of these complications from fossilization is taphonomy, which is its own significant and developing field of paleontology. The combination of reconstructions of ancient environments with the evolution of these environments over time is termed evolutionary paleoecology. Global patterns of diversity can be investigated through paleoecology, suggesting large bursts of diversification and the temporal separation of major faunas forms.<ref name="kelley2013"/> However, these interpretations of changing diversity may be due to biases towards the preservation and discovery of more recent environments over older ones, where the field of taphonomy can become significant.<ref name="jablonski2015"/>

Paleoecology has been able to identify several large-scale patterns in evolution and different faunas. It has been interpreted that communities living nearshore exhibit earlier diversification before spreading to offshore environments, or that tropical latitudes exhibit greater diversification. A largely [[detritus]]-feeding Cambrian fauna appears to be replaced by a suspension-feeding Paleozoic fauna, before itself being replaced by a modern fauna of marine invertebrates, though these faunas and their distinctiveness have also been questioned. Some communities show very little modification over time in a form of statis with stable composition, which changes during brief periods of turnover before stabilizing again. Competition and coevolution driving evolution may be studied through the fossil record, as well as predation and other forms of species interactions. The study of trace fossils, ichnology, also related to paleoecology as the study of fossils arising from behavioral patterns in organisms. Paleobiogeography, paleoclimatology and conservation paleobiology are also related fields of paleoecology, with the latter in particular being relevant to policies that attempt to preserve [[biodiversity]].<ref name="kelley2013"/>

===Paleohistology===
{{main|Paleohistology}}
[[File:Bone histology of Shuvuuia and Confuciusornis.png|thumb|Bone microstructure of dinosaurs ''[[Shuvuuia]]'' and ''[[Confuciusornis]]'' showing lines of arrested growth]]
Paleohistology is the study of the hard tissues of fossils, analogous to the field of histology that studies biological tissues. The field is comparatively restricted as fossils preserve only superficial tissue structure and not molecules that can be found in modern histology, but it still has a long history following the use of [[microscopes]] to study both living and extinct organisms. Fossilization changes the composition of bones and to a lesser extent teeth, though their histology can still be examined through [[thin section]]s. The first use of thin sections in studying tissues in fossils was that of [[Richard Owen]] in a set of volumes in the 1840s that included dinosaurs and pterosaurs, which was simultaneously the first large comparative study of hard tissue histology. The microscopic structure of the bones, [[armour (zoology)|dermal armor]], and teeth of early vertebrates and fossil fish was studies soon after, though polished bone surfaces were used rather than thin sections. The hard tissue structure of these early vertebrates has been used to classify them and separate jawless vertebrates ([[ostracoderm]]s) from those with jaws such as [[placoderms]] and [[acanthodian]]s. Similarly, the paleohistology of [[tetrapods]] has been used as evidence of both their classifications and their function. The internal structure of bones of many tetrapods can be used to identify their age quantitatively through the count of [[growth arrest lines]]. Paleohistology combines structural knowledge with functional interpretations and evolutionary processes to help understand evolution.<ref name="ricqles2021"/>

===Paleopathology===
{{main|Paleopathology}}
[[File:Dilophosaurus pathologies.PNG|thumb|right|upright=0.9|Paleopathologies in bones of a ''[[Dilophosaurus]]'' specimen, plotted onto a life restoration]]
Paleopathology is the study of ancient [[disease]], with the clarification that "disease" is not limited to [[pathogens]] but also any other impairments that can impact health. Though paleopathology is most often discussed in the context of archaeology and human history, it has also included the study of pathologies in any fossil organism since the word was first introduced by Robert Schufeldt in [[1892 in paleontology|1892]]. It is important to separate pathological conditions from alterations that have arisen due to taphonomy, and from that distinction modern [[diagnostic]] techniques can be used to interpret the causes and impacts of pathologies in fossil organisms.<ref name="buikstra2010"/> Biomolecular studies have been able to isolate genetic material in fossil animals and humans to identify specific pathogens, and questioning the strength of these identifications has led to re-evaluations of the history of disease in humans and a more nuanced approach towards the study of disease in humans. Multiple factors can cause skeletal lesions that preserve well in fossils and it can be difficult to distinguish these causes due to not being able to confidently identify causes of [[cause of death|mortality]] and predispositions for vulnerability.<ref name="grauer2017"/> Most of the focus of paleopathology remains on human disease, though the field of animal paleopathology emerged in 1999 and expanded to cover much of the same scope of studies as human paleopathology.<ref name="buikstra2010"/> Specific studies into the [[stress fractures]] in the bones of dinosaurs have used their presence and distribution to identify the activity levels of the impacted animals such as running, migrating, or restraining prey.<ref name="rothschild2001"/>

===Paleophysiology===
{{main|Paleophysiology}}
Paleophysiology is the study of how ancient life coped with its chemical and physical surroundings. Much is known about [[physiological]] changes on a short time scale, but less so about long-term responses including genetic modification. Paleophysiological analysis can investigate how species evolved or went extinct from gradual or rapid environmental change and apply that to modern scenarios to predict responses in the future. Past geological records can be found that resemble those predicted for the future. Extinctions of ancient organisms tend to be selective to certain traits like [[metabolic rate]], temperature tolerance, [[photosynthesis]] and [[homeostasis]], but much is not yet understood about the physiology of ancient organisms. The most useful tool for assessing paleophysiology is through the studies of "[[living fossils]]" that has presumably changed very little physiologically over long periods of time and therefor can be used to indicate paleophysiological conditions. It remains largely unknown how calcifying organisms built robust skeletons at times when atmospheric carbon dioxide levels were high, but the understanding of this process can be applicable to current rising carbon dioxide levels. Similar work may explain how photosynthetic corals and reefs can exist in times of higher acidity and temperatures as in the past. Plants respond to changes in temperature, [[precipitation]], soil quality, and atmospheric gas composition, which can be seen in their fossils. Fossils offer a large array of phenotypes and physiologies that are rare or absent in modern biotas making it possible to assess adaptations that are not found in living species.<ref name="vermeij2015"/>

===Paleoichnology===
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[[File:Hadrosaur tracks.png|thumb|left|Diagram showing how dinosaur footprints preserve in different deposits]] 
Paleoichnology is the study of trace fossils, which can display interactions between organisms or other aspects of behavior. Common trace fossils are the burrows of bivalves or [[worm]]s in shallow water, feeding traces on the deep [[ocean floor]], and the footprints of dinosaurs and other animals in mud and sand beside bodies of water.<ref name="benton2020-20"/> The description of dinosaur tracks goes back to the early 19th century, but larger discussions about paleoichnology and its uses came with the reidentification of supposed plant fossils as invertebrate trackways in the 1880s to 1920s, where modern analogues were introduced to interpret these trace fossils. Advancements by [[Adolf Seilacher]] in the 1960s identified the shortcomings of ichnology: trace fossils were limited in their ability to establish the paleoenvironment, and as they lacked a consistent naming scheme it was difficult to classify and compare trace fossils. Seilacher expanded upon [[ichnotaxonomy]] as a way to classify trace fossils according to the behavior that caused them allowing the identification of sedimentary or environmental contexts.<ref name="kelley2013"/> From this, ichnotaxonomy differentiates between trace fossils created by tracks, burrows or [[boring (earth)|borings]], [[excrement]], and other types of behaviours, rather than describing the organism that created them. One animal can make many different kinds of traces, and one trace can be made my many different kinds of animals.<ref name="benton2020-20"/>

Footprints made by vertebrates can often be compared more with the organism that could have created them, but this identification is not definitive and can be reinterpreted over time. Different kinds of trace fossils can also be dependent on the type of sediment the organisms were interacting with, with feeding traces on the ocean floor fossilizing differently over different [[substrate (biology)|substrates]], and trackways of vertebrates being able to be followed across distances. The understanding that trace fossils directly correlate to sediments means that they can be used as indicators of environment types, termed [[ichnofacies]] and [[paleosols]].<ref name="benton2020-20"/> In rare cases trace fossils can also be preserved alongside body fossils, such as the dinosaur ''[[Oryctodromeus]]'' that is the first to show definitive evidence of [[burrowing]] behavior as its body fossils were found buried within a fossilized burrow.<ref name="varricchio2007"/> Trace fossils are able to be used as markers of biochronology and biogeography for correlation, and some such as coprolites can be used to understand the diets, diseases, parasites, or climates of the organisms that created them. Some trace fossils show evidence of [[gregariousness]] in animals travelling together in the same direction or congregating at a site, while others can show [[pathologies]] in the form of uneven [[gait]]s or pathologic foot impressions. Trackways of footprints can even be used to estimate the size and speed of their creators and their courtship and nesting behaviors.<ref name="lucas2024"/>

===Taphonomy===
{{main|Taphonomy}}
[[File:Fossilization process.jpg|thumb|right|Fossilization process of a pair of [[sauropod]] dinosaurs]]
Taphonomy is the field of study of the process of fossilization and the processes that occur between burial and discovery. The term taphonomy was introduced in [[1940 in paleontology|1940]] by [[Ivan Yefremov]] as a new branch of paleontology, though the consideration of how an organism becomes a fossil predates his work. Taphonomy did not gain prominence as a field until the 1960s when it became important to consider how fossilized deposits relate to their original ecosystems, and the incompleteness of the fossil record became important for evolutionary theories such as punctuated equilibrium. Taphonomic studies of this time involved experimentations to see how the properties of water can transport, sort, or bury bones.<ref name="kelley2013"/> It is unlikely that an organism will become a fossil after death, as many factors can damage or destroy both soft and hard tissues before they are buried. The hardest parts of an organism, such as shells or skeletons, are the most likely to survive to be buried and fossilized, though in rare cases soft tissues can be preserved as well. If a dead organism is buried immediately, and particularly in an [[anaerobic organism|anaerobic]] environment where decay is slowed or stopped, a complete body fossil including both soft and hard tissues may be formed, but even then different chemical or geological processes can alter the fossil, through the [[mineralization (geology)|mineralization]] of organic material, or the forming of [[concretion]]s around them.<ref name="benton2020-5"/>

When not buried immediately, many different taphonomic processes can be involved in the completeness and type of preservation. The transport of organisms from their original position can result in [[disarticulation]] or the incompleteness of material, and exposure to scavengers or the surrounding environment can result in decay, fragmentation, or abrasion. After burial the rock containing fossils may be flattened geologically or deformed by the [[distortion]] of [[metamorphic rock|metamorphic]] activity. Plants can commonly be fossilized as layers of [[carbon]] where all soluble elements of the plant have been removed, and large accumulations of these carbonaceous materials may be transformed into [[coal seam]]s. Many filters influence the preservation and recovery of fossils, all of which impact the completeness of the fossil record. Common organisms in an environment, that lived around shallow bodies of water with little natural [[erosion]] is more likely to be preserved, and after preservation is more likely to be discovered if the rock does not undergo severe metamorphosis, is moved to the surface geologically, and is in a location where it can be exposed to humans.<ref name="benton2020-5"/> Nearly every paleobiological study incorporates a taphonomic assessment and recognizes biases in the fossil record that can impact their reconstructions.<ref name="kelley2013"/>