Editing Dinosaur (section)

==History of study==
{{Further|History of paleontology}}

===Pre-scientific history===
Dinosaur fossils have been known for millennia, although their true nature was not recognized. The Chinese considered them to be [[Chinese dragon|dragon]] bones and documented them as such. For example, ''[[Chronicles of Huayang|Huayang Guo Zhi]]''&nbsp;({{zh|t=華陽國志|labels=no}}), a [[gazetteer]] compiled by [[Chang Qu]]&nbsp;({{zh|t=常璩|labels=no}}) during the [[Jin dynasty (266–420)|Western Jin Dynasty]] (265–316), reported the discovery of dragon bones at Wucheng in [[Sichuan]] Province.<ref name=dong1992/> Villagers in central [[China]] have long unearthed fossilized "dragon bones" for use in [[Traditional Chinese medicine|traditional medicines]].<ref name=BBCdinobonemed/> In [[Europe]], dinosaur fossils were generally believed to be the remains of [[giant]]s and other [[Bible|biblical]] creatures.<ref name=benton2000>{{harvnb|Paul|2000|pp=10–44|loc=chpt. 1: "A Brief History of Dinosaur Paleontology" by Michael J. Benton.}}</ref>

===Early dinosaur research===
[[File:William Buckland c1845.jpg|thumb|upright|left|[[William Buckland]]]]

Scholarly descriptions of what would now be recognized as dinosaur bones first appeared in the late 17th century in England. Part of a bone, now known to have been the femur of a ''[[Megalosaurus]]'',<ref name=WAS97/> was recovered from a limestone quarry at [[Cornwell, Oxfordshire|Cornwell]] near [[Chipping Norton]], Oxfordshire, in 1676. The fragment was sent to [[Robert Plot]], Professor of Chemistry at the [[University of Oxford]] and first curator of the [[Ashmolean Museum]], who published a description in his ''The Natural History of Oxford-shire'' (1677).<ref>{{harvnb|Plot|1677|pp=131–139; illus. opp. p. 142, fig. 4}}</ref> He correctly identified the bone as the lower extremity of the femur of a large animal, and recognized that it was too large to belong to any known species. He therefore concluded it to be the femur of a huge human, perhaps a [[Titan (mythology)|Titan]] or another type of giant featured in legends.<ref>{{harvnb|Plot|1677|p=[https://archive.org/details/naturalhistoryo00plot/page/131/mode/1up]}}</ref><ref>{{cite web |url=http://www.oum.ox.ac.uk/learning/pdfs/plot.pdf |title=Robert Plot |author=<!--Staff writer(s); no by-line.--> |year=2006 |website=Learning more |publisher=[[Oxford University Museum of Natural History]] |location=Oxford |archive-url=https://web.archive.org/web/20061001094736/http://www.oum.ox.ac.uk/learning/pdfs/plot.pdf |archive-date=October 1, 2006 |access-date=November 14, 2019}}</ref> [[Edward Lhuyd]], a friend of [[Isaac Newton|Sir Isaac Newton]], published ''Lithophylacii Britannici ichnographia'' (1699), the first scientific treatment of what would now be recognized as a dinosaur. In it he described and named a sauropod [[tooth]], "[[Rutellum|Rutellum impicatum]]",<ref name=L99/><ref name=DS02/> that had been found in Caswell, near [[Witney]], Oxfordshire.<ref name=G45/>

[[File:Dinosaur coining of the word in 1841.jpg|thumb|[[Richard Owen|Sir Richard Owen]]'s coining of the word ''dinosaur'', in the 1842 revised version of his talk at an 1841 meeting of the [[British association for the advancement of science|British Association for the Advancement of Science]].]]

Between 1815 and 1824, the Rev [[William Buckland]], the first Reader of Geology at the University of Oxford, collected more fossilized bones of ''Megalosaurus'' and became the first person to describe a non-avian dinosaur in a [[scientific journal]].<ref name=WAS97/><ref name=buckland1824/> The second non-avian dinosaur genus to be identified, ''[[Iguanodon]]'', was purportedly discovered in 1822 by [[Mary Ann Mantell]], the wife of English geologist [[Gideon Mantell]], though this is disputed and some historians say Gideon had acquired remains years earlier. Gideon Mantell recognized similarities between his fossils and the bones of modern [[iguana]]s and published his findings in 1825.<ref name=GM25/><ref name=HDS97/>

The study of these "great fossil lizards" soon became of great interest to European and American scientists, and in 1842 the English paleontologist Sir Richard Owen coined the term "dinosaur", using it to refer to the "distinct tribe or sub-order of Saurian Reptiles" that were then being recognized in England and around the world.<ref name=":2">{{Cite web |date=2017-04-28 |title=The 'birth' of dinosaurs |url=https://morethanadodo.com/2017/04/28/the-birth-of-dinosaurs/ |access-date=2023-03-15 |website=More Than A Dodo |archive-date=March 14, 2023 |archive-url=https://web.archive.org/web/20230314201255/https://morethanadodo.com/2017/04/28/the-birth-of-dinosaurs/ |url-status=live }}</ref><ref name=":3">{{Cite news |date=October 16, 2015 |title=The Birth of Dinosaurs: Richard Owen and Dinosauria |url=https://blog.biodiversitylibrary.org/2015/10/the-birth-of-dinosaurs-richard-owen-and-dinosauria.html |access-date=March 15, 2023 |website=Biodiversity Heritage Library |archive-date=March 14, 2023 |archive-url=https://web.archive.org/web/20230314201310/https://blog.biodiversitylibrary.org/2015/10/the-birth-of-dinosaurs-richard-owen-and-dinosauria.html |url-status=live }}</ref><ref name=":4">{{Cite book |last1=Brett-Surman |first1=M. K. |url=https://books.google.com/books?id=pX_l24sDARwC&dq=Hugh+Torrens+Dinosauria+Owen&pg=PA25 |title=The Complete Dinosaur |last2=Holtz |first2=Thomas R. |last3=Farlow |first3=James O. |date=June 27, 2012 |publisher=Indiana University Press |isbn=978-0-253-00849-7 |page=25 }}</ref><ref name=Owen1841/><ref>{{cite Merriam-Webster|Dinosauria|access-date=November 10, 2019}}</ref> The term is derived {{ety|grc|''[[wikt:δεινός|δεινός]]'' (deinos)|terrible, potent or fearfully great||''[[wikt:σαῦρος|σαῦρος]]'' (sauros)|lizard or reptile}}.<ref name=Owen1841/><ref name=LSJ/> Though the taxonomic name has often been interpreted as a reference to dinosaurs' teeth, claws, and other fearsome characteristics, Owen intended it also to evoke their size and majesty.<ref name=FBS97/> Owen recognized that the remains that had been found so far, ''Iguanodon'', ''Megalosaurus'' and ''[[Hylaeosaurus]]'', shared distinctive features, and so decided to present them as a distinct taxonomic group. As clarified by British geologist and historian Hugh Torrens, Owen had given a presentation about fossil reptiles to the British Association for the Advancement of Science in 1841, but reports of the time show that Owen did not mention the word "dinosaur", nor recognize dinosaurs as a distinct group of reptiles in his address. He introduced the Dinosauria only in the revised text version of his talk published in April 1842.<ref name=":2" /><ref name=":3" /> With the backing of [[Albert, Prince Consort|Prince Albert]], the husband of [[Queen Victoria]], Owen established the [[Natural History Museum, London]], to display the national collection of dinosaur fossils and other biological and geological exhibits.<ref name=owen94>{{harvnb|Rupke|1994}}</ref>

===Discoveries in North America===
{{multiple image
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| caption1          = [[Edward Drinker Cope]]
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| caption2          = [[Othniel Charles Marsh]]
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In 1858, [[William Parker Foulke]] discovered the first known American dinosaur, in [[marl]] pits in the small town of [[Haddonfield, New Jersey]]. (Although fossils had been found before, their nature had not been correctly discerned.) The creature was named ''[[Hadrosaurus|Hadrosaurus foulkii]]''. It was an extremely important find: ''Hadrosaurus'' was one of the first nearly complete dinosaur skeletons found ([[Iguanodon#Gideon Mantell, Sir Richard Owen, and the discovery of dinosaurs|the first]] was in 1834, in [[Maidstone|Maidstone, England]]), and it was clearly a bipedal creature. This was a revolutionary discovery as, until that point, most scientists had believed dinosaurs walked on four feet, like other lizards. Foulke's discoveries sparked a wave of interests in dinosaurs in the United States, known as dinosaur mania.<ref name=weishampel06>{{cite journal |last1=Prieto-Marquez |first1=Albert |last2=Weishampel |first2=David B. |last3=Horner |first3=John R. |date=March 2006 |title=The dinosaur ''Hadrosaurus foulkii'', from the Campanian of the East Coast of North America, with a reevaluation of the genus |url=https://app.pan.pl/archive/published/app51/app51-077.pdf |url-status=live |journal=Acta Palaeontologica Polonica |location=Warsaw |publisher=Institute of Paleobiology, Polish Academy of Sciences |volume=51 |issue=1 |pages=77–98 |issn=0567-7920 |archive-url=https://web.archive.org/web/20190622113255/https://app.pan.pl/archive/published/app51/app51-077.pdf |archive-date=June 22, 2019 |access-date=November 5, 2019}}</ref>

Dinosaur mania was exemplified by the fierce rivalry between [[Edward Drinker Cope]] and [[Othniel Charles Marsh]], both of whom raced to be the first to find new dinosaurs in what came to be known as the [[Bone Wars]]. This fight between the two scientists lasted for over 30 years, ending in 1897 when Cope died after spending his entire fortune on the dinosaur hunt. Many valuable dinosaur specimens were damaged or destroyed due to the pair's rough methods: for example, their diggers often used [[dynamite]] to unearth bones. Modern paleontologists would find such methods crude and unacceptable, since blasting easily destroys fossil and stratigraphic evidence. Despite their unrefined methods, the contributions of Cope and Marsh to paleontology were vast: Marsh unearthed 86 new species of dinosaur and Cope discovered 56, a total of 142 new species. Cope's collection is now at the [[American Museum of Natural History]] in New York City, while Marsh's is at the [[Peabody Museum of Natural History]] at [[Yale University]].<ref name=Holmes/>

==="Dinosaur renaissance" and beyond===
{{Main|Dinosaur renaissance}}
[[World War II]] caused a pause in palaeontological research; after the war, research attention was also diverted increasingly to fossil mammals rather than dinosaurs, which were seen as sluggish and cold-blooded.<ref name="taylor2010">{{cite journal |last1=Taylor |first1=M.P. |title=Sauropod dinosaur research: a historical review |journal=Geological Society, London, Special Publications |year=2010 |volume=343 |issue=1 |pages=361–386 |doi=10.1144/SP343.22|bibcode=2010GSLSP.343..361T |s2cid=910635 }}</ref><ref name="Naish">{{cite book |last=Naish |first=D. |year=2009 |title=The Great Dinosaur Discoveries |pages=89–93 |publisher=A & C Black Publishers Ltd. |location=London, UK |isbn=978-1-4081-1906-8}}</ref> At the end of the 1960s, however, the field of dinosaur research experienced a surge in activity that remains ongoing.<ref name="arbour2018">{{cite journal |last1=Arbour |first1=V. |year=2018 |title=Results roll in from the dinosaur renaissance |journal=Science |volume=360 |issue=6389 |page=611 |doi=10.1126/science.aat0451|bibcode=2018Sci...360..611A |s2cid=46887409 }}</ref> Several seminal studies led to this activity. First, [[John Ostrom]] discovered the bird-like [[dromaeosauridae|dromaeosaurid]] theropod ''[[Deinonychus]]'' and described it in 1969. Its anatomy indicated that it was an active predator that was likely warm-blooded, in marked contrast to the then-prevailing image of dinosaurs.<ref name="taylor2010"/> Concurrently, [[Robert T. Bakker]] published a series of studies that likewise argued for active lifestyles in dinosaurs based on anatomical and ecological evidence (see {{section link||Physiology}}),<ref name="bakker1968"/><ref name="bakker1972"/> which were subsequently summarized in his 1986 book ''[[The Dinosaur Heresies]]''.<ref name=bakker86>{{harvnb|Bakker|1986}}</ref>

[[File:Dr. Bob Bakker with Dino.jpg|thumb|left|Paleontologist [[Robert T. Bakker]] with a mounted skeleton of a [[Tyrannosauridae|tyrannosaurid]] (''[[Gorgosaurus|Gorgosaurus libratus]]'')]]
New revelations were supported by an increase in dinosaur discoveries. Major new dinosaur discoveries have been made by paleontologists working in previously unexplored regions, including India, South America, Madagascar, Antarctica, and most significantly China. Across theropods, sauropodomorphs, and ornithischians, the number of named genera began to increase exponentially in the 1990s.<ref name="Genera900"/> In 2008 over 30 new species of dinosaurs were named each year.<ref name="benton2008"/> At least sauropodomorphs experienced a further increase in the number of named species in the 2010s, with an average of 9.3 new species having been named each year between 2009 and 2020. As a consequence, more sauropodomorphs were named between 1990 and 2020 than in all previous years combined.<ref name="cashmore2020">{{cite journal |last1=Cashmore |first1=D.D. |last2=Mannion |first2=P.D. |last3=Upchurch |first3=P. |last4=Butler |first4=R.J. |year=2020 |title=Ten more years of discovery: revisiting the quality of the sauropodomorph dinosaur fossil record |journal=Palaeontology |volume=63 |issue=6 |pages=951–978 |doi=10.1111/pala.12496|bibcode=2020Palgy..63..951C |s2cid=219090716 |doi-access=free }}</ref> These new localities also led to improvements in overall specimen quality, with new species being increasingly named not on scrappy fossils but on more complete skeletons, sometimes from multiple individuals. Better specimens also led to new species being invalidated less frequently.<ref name="benton2008">{{cite journal |last1=Benton |first1=M.J. |year=2008 |title=Fossil quality and naming dinosaurs |journal=Biology Letters |volume=4 |issue=6 |pages=729–732 |doi=10.1098/rsbl.2008.0402|pmid=18796391 |pmc=2614166 }}</ref> Asian localities have produced the most complete theropod specimens,<ref name="cashmore2019">{{cite journal |last1=Cashmore |first1=D.D. |last2=Butler |first2=R.J. |year=2019 |title=Skeletal completeness of the non-avian theropod dinosaur fossil record |journal=Palaeontology |volume=62 |issue=6 |pages=951–981 |doi=10.1111/pala.12436|s2cid=197571209 |doi-access=free |bibcode=2019Palgy..62..951C }}</ref> while North American localities have produced the most complete sauropodomorph specimens.<ref name="cashmore2020"/>

Prior to the dinosaur renaissance, dinosaurs were mostly classified using the traditional rank-based system of [[Linnaean taxonomy]]. The renaissance was also accompanied by the increasingly widespread application of [[cladistics]], a more objective method of classification based on ancestry and shared traits, which has proved tremendously useful in the study of dinosaur systematics and evolution. Cladistic analysis, among other techniques, helps to compensate for an often incomplete and fragmentary fossil record.<ref name="holtz1997">{{cite book |last1=Holtz |first1=T.R. Jr. |last2=Brett-Surman |first2=M.K. |year=1997 |chapter=The Taxonomy and Systematics of Dinosaurs |title=The Complete Dinosaur |publisher=Indiana University Press |location=Bloomington |pages=209–223 |isbn=978-0-253-33349-0 |chapter-url=https://books.google.com/books?id=Hk5ecvEv0GcC&pg=PA209}}</ref><ref name="NYT-20161208">{{cite news |last=St. Fleur |first=Nicholas |title=That Thing With Feathers Trapped in Amber? It Was a Dinosaur Tail |url=https://www.nytimes.com/2016/12/08/science/dinosaur-feathers-amber.html |url-status=live |url-access=registration |date=December 8, 2016 |department=Trilobites |work=The New York Times |location=New York |issn=0362-4331 |archive-url=https://web.archive.org/web/20170831181949/https://www.nytimes.com/2016/12/08/science/dinosaur-feathers-amber.html |archive-date=August 31, 2017 |access-date=December 8, 2016}}</ref> Reference books summarizing the state of dinosaur research, such as [[David B. Weishampel]] and colleagues' ''[[The Dinosauria]]'', made knowledge more accessible<ref name="lockley2000">{{cite journal |last1=Lockley |first1=M.G. |last2=Wright |first2=J.L. |year=2000 |title=Reading About Dinosaurs – An Annotated Bibliography of Books |journal=Journal of Geoscience Education |volume=48 |issue=2 |pages=167–178 |doi=10.5408/1089-9995-48.2.167|bibcode=2000JGeEd..48..167L |s2cid=151426669 }}</ref> and spurred further interest in dinosaur research. The release of the first and second editions of ''The Dinosauria'' in 1990 and 2004, and of a review paper by [[Paul Sereno]] in 1998, were accompanied by increases in the number of published [[phylogenetic tree]]s for dinosaurs.<ref name="lloyd2008">{{cite journal |last1=Lloyd |first1=G.T. |last2=Davis |first2=K.E. |last3=Pisani |first3=D. |last4=Tarver |first4=J.E. |last5=Ruta |first5=R. |last6=Sakamoto |first6=M. |last7=Hone |first7=D.W.E. |last8=Jennings |first8=R. |last9=Benton |first9=M.J. |year=2008 |title=Dinosaurs and the Cretaceous Terrestrial Revolution |journal=Proceedings of the Royal Society B |volume=275 |issue=1650 |pages=2483–2490 |doi=10.1098/rspb.2008.0715|pmid=18647715 |pmc=2603200 }}</ref>

===Soft tissue and molecular preservation===
[[File:Dakota skin impression.jpg|thumb|An ''[[Edmontosaurus]]'' specimen's skin impressions found in 1999]]
Dinosaur fossils are not limited to bones, but also include imprints or mineralized remains of skin coverings, organs, and other tissues. Of these, skin coverings based on [[keratin]] proteins are most easily preserved because of their [[cross-link]]ed, [[hydrophobe|hydrophobic]] molecular structure.<ref name="schweitzer2011">{{cite journal |last1=Schweitzer |first1=M.H. |year=2011 |title=Soft Tissue Preservation in Terrestrial Mesozoic Vertebrates |journal=Annual Review of Earth and Planetary Sciences |volume=39 |pages=187–216 |doi=10.1146/annurev-earth-040610-133502|bibcode=2011AREPS..39..187S }}</ref> Fossils of keratin-based skin coverings or bony skin coverings are known from most major groups of dinosaurs. Dinosaur fossils with scaly skin impressions have been found since the 19th century. [[Samuel Beckles]] discovered a sauropod forelimb with preserved skin in 1852 that was incorrectly attributed to a crocodile; it was correctly attributed by Marsh in 1888 and subject to further study by [[Reginald Hooley]] in 1917.<ref name="hooley1917"/> Among ornithischians, in 1884 Jacob Wortman found skin impressions on the first known specimen of ''[[Edmontosaurus annectens]]'', which were largely destroyed during the specimen's excavation.<ref name="osborn1912">{{cite journal |first1=H.F. |last1=Osborn |year=1912 |title=Integument of the iguanodont dinosaur ''Trachodon'' |journal=Memoirs of the American Museum of Natural History |volume=1 |pages=33–54}}</ref> Owen and Hooley subsequently described skin impressions of ''[[Hypsilophodon]]'' and ''Iguanodon'' in 1885 and 1917.<ref name="hooley1917">{{cite journal |last1=Hooley |first1=R.W. |year=1917 |title=II—On the Integument of ''Iguanodon bernissartensis'', Boulenger, and of ''Morosaurus becklesii'', Mantell |journal=Geological Magazine |volume=4 |issue=4 |pages=148–150 |doi=10.1017/s0016756800192386 |bibcode=1917GeoM....4..148H |s2cid=129640665 |url=https://zenodo.org/record/1537494 |archive-date=April 15, 2023 |access-date=February 20, 2023 |archive-url=https://web.archive.org/web/20230415133707/https://zenodo.org/record/1537494 |url-status=live }}</ref> Since then, scale impressions have been most frequently found among hadrosaurids, where the impressions are known from nearly the entire body across multiple specimens.<ref name="bell2014">{{cite book |last1=Bell |first1=P.R. |year=2014 |chapter=A review of hadrosaur skin impressions |editor-last1=Eberth |editor-first1=D. |editor-last2=Evans |editor-first2=D. |title=The Hadrosaurs: Proceedings of the International Hadrosaur Symposium |pages=572–590 |location=Bloomington |publisher=Princeton University Press}}</ref>

{{multiple image|align=left|perrow=1/2|caption_align=center
|image1=Sinosauropteryx color.jpg|caption1=Color restoration of ''[[Sinosauropteryx]]''
|image2=Psittacosaurus (Vinther et al. 2016, cropped).png|caption2=Color restoration of ''[[Psittacosaurus]]''
}}
Starting from the 1990s, major discoveries of exceptionally preserved fossils in deposits known as conservation [[Lagerstätte]]n contributed to research on dinosaur soft tissues.<ref name="eliason2017">{{cite journal |last1=Eliason |first1=C.M. |last2=Hudson |first2=L. |last3=Watts |first3=T. |last4=Garza |first4=H. |last5=Clarke |first5=J.A. |year=2017 |title=Exceptional preservation and the fossil record of tetrapod integument |journal=Proceedings of the Royal Society B |volume=284 |issue=1862 |pages=1–10 |doi=10.1098/rspb.2017.0556|pmid=28878057 |pmc=5597822 }}</ref><ref name="benton1998">{{cite journal |last1=Benton |first1=M.J. |year=1998 |title=Dinosaur fossils with soft parts |journal=Trends in Ecology & Evolution |volume=13 |issue=8 |pages=303–304 |doi=10.1016/s0169-5347(98)01420-7|pmid=21238317 |bibcode=1998TEcoE..13..303B |url=http://doc.rero.ch/record/14715/files/PAL_E1646.pdf }}</ref> Chiefly among these were the rocks that produced the [[Jehol Biota|Jehol]] (Early Cretaceous) and [[Yanliao Biota|Yanliao]] (Mid-to-Late Jurassic) [[biota (ecology)|biota]]s of northeastern China, from which hundreds of dinosaur specimens bearing impressions of feather-like structures (both closely related to birds and otherwise, see {{section link||Origin of birds}}) have been described by [[Xu Xing (paleontologist)|Xing Xu]] and colleagues.<ref name="zhou2017">{{cite journal |last1=Zhou |first1=Z.-H. |last2=Wang |first2=Y. |year=2017 |title=Vertebrate assemblages of the Jurassic Yanliao Biota and the Early Cretaceous Jehol Biota: Comparisons and implications |journal=Palaeoworld |volume=26 |issue=2 |pages=241–252 |doi=10.1016/j.palwor.2017.01.002}}</ref><ref name="norell2005">{{cite journal |last1=Norell |first1=M.A. |last2=Xu |first2=X. |year=2005 |title=Feathered Dinosaurs |journal=Annual Review of Earth and Planetary Sciences |volume=33 |pages=277–299 |doi=10.1146/annurev.earth.33.092203.122511|bibcode=2005AREPS..33..277N }}</ref> In living reptiles and mammals, pigment-storing cellular structures known as [[melanosome]]s are partially responsible for producing colouration.<ref name="roy2020"/><ref name="vinther2020">{{cite journal |last1=Vinther |first1=J. |year=2020 |title=Reconstructing Vertebrate Paleocolor |journal=Annual Review of Earth and Planetary Sciences |volume=48 |pages=345–375 |doi=10.1146/annurev-earth-073019-045641|bibcode=2020AREPS..48..345V |s2cid=219768255 |doi-access=free }}</ref> Both chemical traces of [[melanin]] and characteristically shaped melanosomes have been reported from feathers and scales of Jehol and Yanliao dinosaurs, including both theropods and ornithischians.<ref name="zhang2010">{{cite journal |last1=Zhang |first1=F. |last2=Kearns |first2=S.L. |last3=Orr |first3=P.J. |last4=Benton |first4=M.J. |last5=Zhou |first5=Z. |last6=Johnson |first6=D. |last7=Xu |first7=X. |last8=Wang |first8=X. |year=2010 |title=Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds |journal=Nature |volume=463 |issue=7284 |pages=1075–1078 |doi=10.1038/nature08740 |pmid=20107440 |bibcode=2010Natur.463.1075Z |s2cid=205219587 |url=http://oro.open.ac.uk/22432/2/41064696.pdf |archive-date=February 2, 2014 |access-date=February 20, 2023 |archive-url=https://web.archive.org/web/20140202214645/http://oro.open.ac.uk/22432/2/41064696.pdf |url-status=live }}</ref> This has enabled multiple full-body reconstructions of [[dinosaur colouration]], such as for ''[[Sinosauropteryx]]''<ref name="smithwick2017">{{cite journal |last1=Smithwick |first1=F.M. |last2=Nicholls |first2=R. |last3=Cuthill |first3=I.C. |last4=Vinther |first4=J. |year=2017 |title=Countershading and Stripes in the Theropod Dinosaur ''Sinosauropteryx'' Reveal Heterogeneous Habitats in the Early Cretaceous Jehol Biota |journal=Current Biology |volume=27 |issue=21 |pages=3337–3343.e2 |doi=10.1016/j.cub.2017.09.032 |pmid=29107548 |doi-access=free|bibcode=2017CBio...27E3337S |hdl=1983/8ee95b15-5793-42ad-8e57-da6524635349 |hdl-access=free }}</ref> and ''[[Psittacosaurus]]''<ref name="vinther2016">{{cite journal |last1=Vinther |first1=J. |last2=Nicholls |first2=R. |last3=Lautenschlager |first3=S. |last4=Pittman |first4=M. |last5=Kaye |first5=T.G. |last6=Rayfield |first6=E. |last7=Mayr |first7=G. |last8=Cuthill |first8=I.C. |year=2016 |title=3D Camouflage in an Ornithischian Dinosaur |journal=Current Biology |volume=26 |issue=18 |pages=2456–2462 |doi=10.1016/j.cub.2016.06.065 |pmid=27641767 |pmc=5049543|bibcode=2016CBio...26.2456V }}</ref> by Jakob Vinther and colleagues, and similar techniques have also been extended to dinosaur fossils from other localities.<ref name="roy2020">{{cite journal |last1=Roy |first1=A. |last2=Pittman |first2=M. |last3=Saitta |first3=E.T. |last4=Kaye |first4=T.G. |last5=Xu |first5=X. |year=2020 |title=Recent advances in amniote palaeocolour reconstruction and a framework for future research |journal=Biological Reviews |volume=95 |issue=1 |pages=22–50 |doi=10.1111/brv.12552|pmid=31538399 |pmc=7004074 }}</ref> (However, some researchers have also suggested that fossilized melanosomes represent bacterial remains.<ref name="lindgren2015">{{cite journal |last1=Lindgren |first1=J. |last2=Moyer |first2=A. |last3=Schweitzer |first3=M.H. |last4=Sjövall |first4=P. |last5=Uvdal |first5=P. |last6=Nilsson |first6=D.E. |last7=Heimdal |first7=J. |last8=Engdahl |first8=A. |last9=Gren |first9=J.A. |last10=Schultz |first10=B.P. |last11=Kear |first11=B.P. |year=2015 |title=Interpreting melanin-based coloration through deep time: a critical review |journal=Proceedings of the Royal Society B |volume=282 |issue=1813 |page=20150614 |pmid=26290071 |doi=10.1098/rspb.2015.0614 |pmc=4632609}}</ref><ref name="schweitzer2015">{{cite journal |last1=Schweitzer |first1=M.H. |last2=Lindgren |first2=J. |last3=Moyer |first3=A.E. |year=2015 |title=Melanosomes and ancient coloration re-examined: a response to Vinther 2015 (DOI 10.1002/bies.201500018) |journal=BioEssays |volume=37 |issue=11 |pages=1174–1183 |doi=10.1002/bies.201500061|pmid=26434749 |s2cid=45178498 }}</ref>) Stomach contents in some Jehol and Yanliao dinosaurs closely related to birds have also provided indirect indications of diet and digestive system anatomy (e.g., [[crop (anatomy)|crops]]).<ref name="zhou2014">{{cite journal |last1=Zhou |first1=Z. |year=2014 |title=The Jehol Biota, an Early Cretaceous terrestrial Lagerstätte: new discoveries and implications |journal=National Science Review |volume=1 |issue=4 |pages=543–559 |doi=10.1093/nsr/nwu055|doi-access=free }}</ref><ref name="oconnor2019">{{cite journal |last1=O'Connor |first1=J.K. |last2=Zhou |first2=Z. |year=2019 |title=The evolution of the modern avian digestive system: insights from paravian fossils from the Yanliao and Jehol biotas |journal=Palaeontology |volume=63 |issue=1 |pages=13–27 |doi=10.1111/pala.12453|s2cid=210265348 }}</ref> More concrete evidence of internal anatomy has been reported in ''[[Scipionyx]]'' from the [[Pietraroja Plattenkalk]] of Italy. It preserves portions of the intestines, colon, liver, muscles, and windpipe.<ref name="softtissue"/>

[[File:9121 - Milano, Museo storia naturale - Scipionyx samniticus - Foto Giovanni Dall'Orto 22-Apr-2007a.jpg|thumb|''[[Scipionyx]]'' fossil with intestines, [[Museo Civico di Storia Naturale di Milano|Natural History Museum of Milan]]]]
Concurrently, a line of work led by [[Mary Higby Schweitzer]], [[Jack Horner (paleontologist)|Jack Horner]], and colleagues reported various occurrences of preserved soft tissues and proteins within dinosaur bone fossils. Various mineralized structures that likely represented [[red blood cell]]s and [[collagen]] fibres had been found by Schweitzer and others in [[tyrannosauridae|tyrannosaurid]] bones as early as 1991.<ref name="morell1993">{{cite journal |last1=Morell |first1=V. |year=1993 |title=Dino DNA: the Hunt and the Hype |journal=Science |volume=261 |issue=5118 |pages=160–162 |doi=10.1126/science.8327889|pmid=8327889 |bibcode=1993Sci...261..160M }}</ref><ref name="pawlicki1996">{{cite journal |last1=Pawlicki |first1=R. |last2=Korbel |first2=A. |last3=Kubiak |first3=H. |year=1996 |title=Cells, Collagen Fibrils and Vessels in Dinosaur Bone |journal=Nature |volume=211 |issue=5049 |pages=655–657 |doi=10.1038/211655a0|pmid=5968744 |s2cid=4181847 }}</ref><ref name="pawlicki1998">{{cite journal |last1=Pawlicki |first1=R. |last2=Nowogrodzka-Zagórska |first2=M. |year=1998 |title=Blood vessels and red blood cells preserved in dinosaur bones |journal=Annals of Anatomy - Anatomischer Anzeiger |volume=180 |issue=1 |pages=73–77 |doi=10.1016/S0940-9602(98)80140-4|pmid=9488909 }}</ref> However, in 2005, Schweitzer and colleagues reported that a femur of ''[[Tyrannosaurus]]'' preserved soft, flexible tissue within, including [[blood vessel]]s, [[osteon|bone matrix]], and connective tissue (bone fibers) that had retained their microscopic structure.<ref name=Schweitzer2005/> This discovery suggested that original soft tissues could be preserved over geological time,<ref name="schweitzer2011"/> with multiple mechanisms having been proposed.<ref name="anderson2023">{{cite journal |last1=Anderson |first1=L.A. |year=2023 |title=A chemical framework for the preservation of fossil vertebrate cells and soft tissues |journal=Earth-Science Reviews |volume=240 |page=104367 |doi=10.1016/j.earscirev.2023.104367|bibcode=2023ESRv..24004367A |s2cid=257326012 |doi-access=free }}</ref> Later, in 2009, Schweitzer and colleagues reported that a ''[[Brachylophosaurus]]'' femur preserved similar microstructures, and [[immunohistochemistry|immunohistochemical]] techniques (based on [[antibody]] binding) demonstrated the presence of proteins such as collagen, [[elastin]], and [[laminin]].<ref name="schweitzer2009">{{cite journal |last1=Schweitzer |first1=M.H. |last2=Zheng |first2=W. |last3=Organ |first3=C.L. |last4=Avci |first4=R. |last5=Suo |first5=Z. |last6=Freimark |first6=L.M. |last7=LeBleu |first7=V.S. |last8=Duncan |first8=M.B. |last9=van der Heiden |first9=M.G. |last10=Neveu |first10=J.M. |last11=Lane |first11=W.S. |last12=Cottrell |first12=J.S. |last13=Horner |first13=J.R. |last14=Cantley |first14=L.C. |last15=Kalluri |first15=R. |last16=Asara |first16=J.M. |year=2009 |title=Biomolecular characterization and protein sequences of the Campanian hadrosaur ''B. canadensis'' |journal=Science |volume=324 |issue=5927 |pages=626–631 |doi=10.1126/science.1165069|pmid=19407199 |bibcode=2009Sci...324..626S |s2cid=5358680 }}</ref> Both specimens yielded collagen protein sequences that were viable for [[molecular phylogenetics|molecular phylogenetic analyses]], which grouped them with birds as would be expected.<ref name="schweitzer2009"/><ref name="organ2008">{{cite journal |last1=Organ |first1=C.L. |last2=Schweitzer |first2=M.H. |last3=Zheng |first3=W. |last4=Freimark |first4=L.M. |last5=Cantley |first5=L.C. |last6=Asara |first6=J.M. |year=2008 |title=Molecular Phylogenetics of Mastodon and ''Tyrannosaurus rex'' |journal=Science |volume=320 |issue=5875 |page=499 |doi=10.1126/science.1154284|pmid=18436782 |bibcode=2008Sci...320..499O |s2cid=24971064 }}</ref> The extraction of fragmentary DNA has also been reported for both of these fossils,<ref name="schweitzer2013">{{cite journal |last1=Schweitzer |first1=M.H. |last2=Zheng |first2=W. |last3=Cleland |first3=T.P. |last4=Bern |first4=M. |year=2013 |title=Molecular analyses of dinosaur osteocytes support the presence of endogenous molecules |journal=[[Bone (journal)|Bone]] |location=Amsterdam |publisher=Elsevier |volume=52 |issue=1 |pages=414–423 |doi=10.1016/j.bone.2012.10.010 |issn=8756-3282 |pmid=23085295}}</ref> along with a specimen of ''[[Hypacrosaurus]]''.<ref name="bailleul2020">{{cite journal |last1=Bailleul |first1=A.M. |last2=Zheng |first2=W. |last3=Horner |first3=J.R. |last4=Hall |first4=B.K. |last5=Holliday |first5=C.M. |last6=Schweitzer |first6=M.H. |year=2020 |title=Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage |journal=National Science Review |volume=7 |issue=4 |pages=815–822 |doi=10.1093/nsr/nwz206|pmid=34692099 |pmc=8289162 }}</ref> In 2015, Sergio Bertazzo and colleagues reported the preservation of collagen fibres and red blood cells in eight Cretaceous dinosaur specimens that did not show any signs of exceptional preservation, indicating that soft tissue may be preserved more commonly than previously thought.<ref name="bertazzo2015">{{cite journal |last1=Bertazzo |first1=S. |last2=Maidment |first2=S.C.R. |author2-link=Susannah Maidment |last3=Kallepitis |first3=C. |last4=Fearn |first4=S. |last5=Stevens |first5=M.M. |last6=Xie |first6=H.-N. |display-authors=3 |year=2015 |title=Fibres and cellular structures preserved in 75-million-year-old dinosaur specimens |journal=[[Nature Communications]] |volume=6 |page=7352 |bibcode=2015NatCo...6.7352B |doi=10.1038/ncomms8352 |issn=2041-1723 |pmc=4468865 |pmid=26056764}}</ref> Suggestions that these structures represent bacterial [[biofilm]]s<ref name="kaye2008">{{cite journal |last1=Kaye |first1=T.G. |last2=Gaugler |first2=G. |last3=Sawlowicz |first3=Z. |year=2008 |title=Dinosaurian Soft Tissues Interpreted as Bacterial Biofilms |journal=PLOS ONE |volume=3 |issue=7 |page=e2808 |doi=10.1371/journal.pone.0002808|pmid=18665236 |pmc=2483347 |bibcode=2008PLoSO...3.2808K |doi-access=free }}</ref> have been rejected,<ref name="peterson2010">{{cite journal |last1=Peterson |first1=J.E. |last2=Lenczewski |first2=M.E. |last3=Scherer |first3=R.P. |year=2010 |title=Influence of Microbial Biofilms on the Preservation of Primary Soft Tissue in Fossil and Extant Archosaurs |journal=PLOS ONE |volume=5 |issue=10 |page=e13334 |bibcode=2010PLoSO...513334P |doi=10.1371/journal.pone.0013334 |doi-access=free |issn=1932-6203 |pmc=2953520 |pmid=20967227}}</ref> but cross-contamination remains a possibility that is difficult to detect.<ref name="buckley2017">{{cite journal |last1=Buckley |first1=M. |last2=Warwood |first2=S. |last3=van Dongen |first3=B. |last4=Kitchener |first4=A.C. |last5=Manning |first5=P.L. |year=2017 |title=A fossil protein chimera; difficulties in discriminating dinosaur peptide sequences from modern cross-contamination |journal=Proceedings of the Royal Society B |volume=284 |issue=1855 |doi=10.1098/rspb.2017.0544|pmid=28566488 |pmc=5454271 }}</ref>