Editing Feather (section)

===Feathered dinosaurs===
{{Main|Feathered dinosaurs}}
[[File:Archaeopteryx lithographica (Berlin specimen).jpg|thumb|left|upright|''[[Archaeopteryx lithographica]]'' (Berlin specimen)]]
Several non-avian [[feathered dinosaurs|dinosaurs]] had feathers on their limbs that would not have functioned for flight.<ref name="NYT-20161208" /><ref name=Prum2003/> One theory suggests that feathers originally evolved on dinosaurs due to their [[Thermal insulation|insulation]] properties; then, small dinosaur species which grew longer feathers may have found them helpful in gliding, leading to the evolution of proto-birds like ''[[Archaeopteryx]]'' and ''[[Microraptor]] zhaoianus''. Another theory posits that the original adaptive advantage of early feathers was their pigmentation or iridescence, contributing to sexual preference in mate selection.<ref>
{{Cite journal|author1=Dimond, C. C. |author2=R. J. Cabin |author3=J. S. Brooks |journal=BIOS
|title=Feathers, Dinosaurs, and Behavioral Cues: Defining the Visual Display Hypothesis for the Adaptive Function of Feathers in Non-Avian Theropods|volume=82|year=2011|pages=58–63|doi=10.1893/011.082.0302|issue=3|s2cid=98221211
}}
</ref> Dinosaurs that had feathers or protofeathers include ''[[Pedopenna]] daohugouensis''<ref>
{{Cite journal|journal= Naturwissenschaften|title=A new maniraptoran dinosaur from China with long feathers on the metatarsus|volume=92|issue=4|pages=173–177|author1=Xu, Xing  |author2=Fucheng Zhang|doi=10.1007/s00114-004-0604-y|year= 2005|pmid= 15685441|bibcode=2005NW.....92..173X|s2cid=789908}}
</ref> and ''[[Dilong paradoxus]]'', a [[tyrannosauroid]] which is 60 to 70 million years older than ''[[Tyrannosaurus|Tyrannosaurus rex]].''<ref>
{{Cite journal|author=Xu, Xing|s2cid=1516713|title=Feathered dinosaurs from China and the evolution of major avian characters|journal=Integrative Zoology|volume=1|issue=1|pages=4–11|year=2006|doi=10.1111/j.1749-4877.2006.00004.x|pmid=21395983|doi-access=free}}</ref>

The majority of dinosaurs known to have had feathers or protofeathers are [[Theropoda|theropods]], however featherlike "filamentous integumentary structures" are also known from the [[ornithischian]] dinosaurs ''[[Tianyulong]]'' and ''[[Psittacosaurus]]''.<ref>{{Cite journal|author1=Zheng, X. T. |author2=H. L. You |author3= X. Xu |author4= Z. M. Dong |name-list-style=amp |journal=Nature|title=An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures|volume=458|year=2009|pages=333–336|doi=10.1038/nature07856|pmid=19295609|issue=7236|bibcode = 2009Natur.458..333Z |s2cid=4423110 }}</ref> The exact nature of these structures is still under study. However, it is believed that the stage-1 feathers (see [[Feather#Evolutionary stages|Evolutionary stages]] section below) such as those seen in these two ornithischians likely functioned in display.<ref name="xu&guo2009"/> In 2014, the ornithischian ''[[Kulindadromeus]]'' was reported as having structures resembling stage-3 feathers.<ref name="Godefroit2014" /> The likelihood of scales evolving on early dinosaur ancestors are high. However, this was by assuming that primitive pterosaurs were scaly.<ref>{{Cite journal|last1=Barrett|first1=Paul M.|last2=Evans|first2=David C.|last3=Campione|first3=Nicolás E.|date=2015-06-30|title=Evolution of dinosaur epidermal structures|journal=Biology Letters|volume=11|issue=6|page=20150229|doi=10.1098/rsbl.2015.0229|pmc=4528472|pmid=26041865}}</ref><ref name="youtube.com">{{Citation|title=Those feathers won't stick: maximum likelihood modelling supports scales as primitive for Dinosauria (The 66th Symposium on Vertebrate Palaeontology and Comparative Anatomy)|url=https://www.youtube.com/watch?v=2MOCbXPwshA| archive-url=https://ghostarchive.org/varchive/youtube/20211211/2MOCbXPwshA| archive-date=2021-12-11 | url-status=live|publication-date=November 9, 2018|language=en|access-date=2021-10-03}}{{cbignore}}</ref> A 2016 study analyzes the pulp morphology of the tail bristles of ''Psittacosaurus'' and finds they are similar to feathers but notes that they are also similar to the bristles on the head of the [[Congo peafowl]], the beard of the [[Turkey (bird)|turkey]], and the spine on the head of the [[horned screamer]].<ref>{{Cite journal |last1=Mayr |first1=Gerald |last2=Pittman |first2=Michael |last3=Saitta |first3=Evan |last4=Kaye |first4=Thomas G. |last5=Vinther |first5=Jakob |date=August 30, 2016 |editor-last=Benson |editor-first=Roger |title=Structure and homology of Psittacosaurus tail bristles |url=https://onlinelibrary.wiley.com/doi/10.1111/pala.12257 |journal=Palaeontology |language=en |volume=59 |issue=6 |pages=793–802 |doi=10.1111/pala.12257|bibcode=2016Palgy..59..793M |hdl=1983/029c668f-08b9-45f6-a0c5-30ce9256e593 |s2cid=89156313 |hdl-access=free }}</ref> A reestimation of maximum likelihoods by paleontologist [[Thomas R. Holtz Jr.|Thomas Holtz]] finds that filaments were more likely to be the ancestral state of dinosaurs.<ref>{{Cite web |last=Holtz |first=Thomas |date=2018-10-19 |title="Integumentary Status: It's Complicated': Phylogenetic, Sedimentary, and Biological Impediments to Resolving the Ancestral Integument of Mesozoic Dinosauria |url=https://vertpaleo.org/wp-content/uploads/2021/03/SVP-2018-program-book-V4-FINAL-with-covers-9-24-18.pdf |access-date=2022-07-16 |website=Society of Vertebrate Paleontology |language=en-US}}</ref>

In 2010, a [[Carcharodontosauridae|carcharodontosaurid]] named [[Concavenator|''Concavenator corcovatus'']] was found to have [[Flight feather#Remiges|remiges]] on the ulna suggesting it might have had quill-like structures on the ams.<ref>{{Cite journal|last1=Ortega|first1=Francisco|last2=Escaso|first2=Fernando|last3=Sanz|first3=José L.|date=September 9, 2010|title=A bizarre, humped Carcharodontosauria (Theropoda) from the Lower Cretaceous of Spain|url=https://www.nature.com/articles/nature09181|journal=Nature|language=en|volume=467|issue=7312|pages=203–206|doi=10.1038/nature09181|pmid=20829793|bibcode=2010Natur.467..203O|s2cid=4395795|issn=1476-4687}}</ref> However, Foth et al. 2014 disagress with the publication where they point out that the bumps on the ulna of ''Concavenator'' are on the [[Anatomical terms of location#Main terms|anterolateral]] which is unlike remiges which are in a [[Anatomical terms of location#Main terms|posterolateral]] on the ulna of some birds, they consider it more likely that these are attachments for interosseous ligaments.<ref>{{Cite journal|last1=Foth|first1=Christian|last2=Tischlinger|first2=Helmut|last3=Rauhut|first3=Oliver W.M.|date=2014-06-02|title=New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers|url=https://www.nature.com/articles/nature13467|journal=Nature|volume=511|issue=7507|pages=79–82|doi=10.1038/nature13467|pmid=24990749|bibcode=2014Natur.511...79F|s2cid=4464659}}</ref> This was refuted by Cuesta Fidalgo and her colleagues, they pointed out that these bumps on the ulna are posterolateral which is unlike that of interosseous ligaments.<ref>{{Cite journal |last1=Cuesta |first1=Elena |last2=Ortega |first2=Francisco |last3=Sanz |first3=José Luis |date=2018-07-04 |title=Appendicular osteology of Concavenator corcovatus (Theropoda: Carcharodontosauridae) from the Lower Cretaceous of Spain |journal=Journal of Vertebrate Paleontology |volume=38 |issue=4 |pages=(1)–(24) |doi=10.1080/02724634.2018.1485153 |s2cid=91976402 |issn=0272-4634|url=https://figshare.com/articles/journal_contribution/7177802 }}</ref>

Since the 1990s, dozens of feathered dinosaurs have been discovered in the clade [[Maniraptora]], which includes the clade Avialae and the recent common ancestors of birds, [[Oviraptorosauria]] and [[Deinonychosauria]]. In 1998, the discovery of a feathered oviraptorosaurian, ''Caudipteryx zoui'', challenged the notion of feathers as a structure exclusive to Avialae.<ref>{{Cite journal|doi=10.1038/31635 |author=Ji, Q. |author2=P. J. Currie |author3=M. A. Norell |author4=S. A. Ji
|title=Two feathered dinosaurs from northeastern China |journal=Nature |volume=393 |year=1998 |pages=753–761
|issue=6687|bibcode = 1998Natur.393..753Q |s2cid=205001388
|url=http://doc.rero.ch/record/31829/files/PAL_E1436.pdf
}}
</ref> Buried in the Yixian Formation in Liaoning, China, ''C. zoui'' lived during the Early Cretaceous Period. Present on the forelimbs and tails, their integumentary structure has been accepted{{by whom|date=April 2014}} as pennaceous vaned feathers based on the rachis and herringbone pattern of the barbs. In the clade Deinonychosauria, the continued divergence of feathers is also apparent in the families [[Troodontidae]] and [[Dromaeosauridae]]. Branched feathers with rachis, barbs, and barbules were discovered in many members including ''Sinornithosaurus millenii'', a dromaeosaurid found in the Yixian formation (124.6 MYA).<ref>
{{Cite journal|doi=10.1038/35065589 |author1=Xu, X. |author2=H. H. Zhou |author3= R. O. Prum  |name-list-style=amp |title=Branched integumental structures in Sinornithosaurus and the origin of feathers |journal=Nature |volume=410
|issue=6825 |year=2001 |pages=200–204 |pmid=11242078 |bibcode=2001Natur.410..200X |s2cid=4426803 }}</ref>

Previously, a temporal paradox existed in the evolution of feathers—theropods with highly derived bird-like characteristics occurred at a later time than ''[[Archaeopteryx]]''—suggesting that the descendants of birds arose before the ancestor. However, the discovery of ''Anchiornis huxleyi'' in the Late Jurassic Tiaojishan Formation (160 MYA) in western Liaoning in 2009<ref>
{{Cite journal |author=Hu, D. Y. |author2=L. H. Hou |author3=L. J. Zhang |author4=X. Xu
|title=A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus |journal=Nature
|volume=461 |issue=7264 |year=2009 |pages=640–643 |pmid=19794491 |doi=10.1038/nature08322
|bibcode=2009Natur.461..640H|s2cid=205218015 }}
</ref><ref>
{{Cite journal|author1=Xu, X. |author2=Q. Zhao |author3= M. Norell |author4=C. Sullivan |author5= D. Hone |author6=G. Erickson |author7= X. L. Wang |title=A new feathered maniraptoran dinosaur fossil that fills a morphological gap in avian origin
|journal=Chinese Science Bulletin |volume=54 |year=2009 |pages=430–435 |doi=10.1007/s11434-009-0009-6|issue=3|bibcode=2009SciBu..54..430X |display-authors=etal|doi-access=free }}
</ref>
resolved this paradox. By predating ''Archaeopteryx'', ''Anchiornis'' proves the existence of a modernly feathered theropod ancestor, providing insight into the dinosaur-bird transition. The specimen shows distribution of large pennaceous feathers on the forelimbs and tail, implying that pennaceous feathers spread to the rest of the body at an earlier stage in theropod evolution.<ref>
{{Cite journal|author=Witmer, L. M. |title=Feathered dinosaurs in a tangle |journal=Nature |volume=461 |issue=7264
|year=2009 |pages=601–602 |pmid=19794481 |doi=10.1038/461601a|bibcode = 2009Natur.461..601W |s2cid=205049989 |doi-access=free }}
</ref> The development of pennaceous feathers did not replace earlier filamentous feathers. Filamentous feathers are preserved alongside modern-looking flight feathers – including some with modifications found in the feathers of extant diving birds – in 80 million year old amber from Alberta.<ref>
{{cite news | url=https://www.cbc.ca/news/science/dinosaur-feathers-found-in-alberta-amber-1.1086765 | work=CBC News | title=Dinosaur feathers found in Alberta amber | date=15 September 2011 | url-status=live | archive-url=https://web.archive.org/web/20110915200138/http://www.cbc.ca/news/canada/edmonton/story/2011/09/15/science-dinosaur-feathers.html | archive-date=15 September 2011 }}
</ref>

Two small wings trapped in amber dating to 100 mya show [[plumage]] existed in some bird predecessors. The wings most probably belonged to [[enantiornithes]], a diverse group of avian dinosaurs.<ref>{{Cite web|url=http://news.nationalgeographic.com/2016/06/dinosaur-bird-feather-burma-amber-myanmar-flying-paleontology-enantiornithes|title=Rare Dinosaur-Era Bird Wings Found Trapped in Amber|date=2016-06-28|access-date=2016-06-28|url-status=dead|archive-url=https://web.archive.org/web/20160628165734/http://news.nationalgeographic.com/2016/06/dinosaur-bird-feather-burma-amber-myanmar-flying-paleontology-enantiornithes/|archive-date=28 June 2016}}</ref><ref>{{Cite journal|last1=Xing|first1=Lida|last2=McKellar|first2=Ryan C.|last3=Wang|first3=Min|last4=Bai|first4=Ming|last5=O'Connor|first5=Jingmai K.|last6=Benton|first6=Michael J.|last7=Zhang|first7=Jianping|last8=Wang|first8=Yan|last9=Tseng|first9=Kuowei|date=2016-06-28|title=Mummified precocial bird wings in mid-Cretaceous Burmese amber|journal=Nature Communications|language=en|volume=7|page=12089|doi=10.1038/ncomms12089|pmid=27352215|pmc=4931330|bibcode=2016NatCo...712089X}}</ref>

A large [[Phylogenetics|phylogenetic]] analysis of early dinosaurs by Matthew Baron, [[David B. Norman]] and Paul Barrett (2017) found that [[Theropoda]] is actually more closely related to [[Ornithischia]], to which it formed the [[sister group]] within the [[clade]] [[Ornithoscelida]]. The study also suggested that if the feather-like structures of theropods and ornithischians are of common evolutionary origin then it would be possible that feathers were restricted to Ornithoscelida. If so, then the origin of feathers would have likely occurred as early as the [[Middle Triassic]],<ref name="Ornithoscelida">{{cite journal | last1 = Baron | first1 = M.G. | last2 = Norman | first2 = D.B. | last3 = Barrett | first3 = P.M. | year = 2017 | title = A new hypothesis of dinosaur relationships and early dinosaur evolution | journal = Nature | volume = 543 | issue = 7646| pages = 501–506 | doi = 10.1038/nature21700 | pmid = 28332513 | bibcode = 2017Natur.543..501B | s2cid = 205254710 }}</ref> though this has been disagreed upon.<ref>{{Cite journal |last1=Yang |first1=Zixiao |last2=Jiang |first2=Baoyu |last3=McNamara |first3=Maria E. |last4=Kearns |first4=Stuart L. |last5=Pittman |first5=Michael |last6=Kaye |first6=Thomas G. |last7=Orr |first7=Patrick J. |last8=Xu |first8=Xing |last9=Benton |first9=Michael J. |date=December 17, 2018 |title=Pterosaur integumentary structures with complex feather-like branching |url=https://cora.ucc.ie/bitstream/handle/10468/8311/8816_Yang_et_al_2019_NEE_Pterosaur_feathers.pdf?sequence=1&isAllowed=y |journal=Nature Ecology & Evolution |language=en |volume=3 |issue=1 |pages=24–30 |doi=10.1038/s41559-018-0728-7 |pmid=30568282 |bibcode=2018NatEE...3...24Y |hdl=1983/1f7893a1-924d-4cb3-a4bf-c4b1592356e9 |s2cid=56480710 |issn=2397-334X}}</ref><ref>{{Cite journal |last1=Langer |first1=Max C. |last2=Ezcurra |first2=Martín D. |last3=Rauhut |first3=Oliver W. M. |last4=Benton |first4=Michael J. |last5=Knoll |first5=Fabien |last6=McPhee |first6=Blair W. |last7=Novas |first7=Fernando E. |last8=Pol |first8=Diego |last9=Brusatte |first9=Stephen L. |date=November 2, 2017 |title=Untangling the dinosaur family tree |url=https://research-information.bris.ac.uk/ws/files/136903911/Langer_et_al._reply_to_Baron_et_al._mjb.pdf |journal=Nature |language=en |volume=551 |issue=7678 |pages=E1–E3 |doi=10.1038/nature24011 |pmid=29094688 |bibcode=2017Natur.551E...1L |hdl=1983/d088dae2-c7fa-4d41-9fa2-aeebbfcd2fa3 |s2cid=205260354 |issn=1476-4687}}</ref> The lack of feathers present in large sauropods and ankylosaurs could be that feathers were suppressed by genomic regulators.<ref>{{Cite journal |last1=Benton |first1=Michael J. |last2=Dhouailly |first2=Danielle |last3=Jiang |first3=Baoyu |last4=McNamara |first4=Maria |date=2019-09-01 |title=The Early Origin of Feathers |url=https://cora.ucc.ie/bitstream/handle/10468/8068/10285.pdf?sequence=1 |journal=Trends in Ecology & Evolution |language=en |volume=34 |issue=9 |pages=856–869 |doi=10.1016/j.tree.2019.04.018 |pmid=31164250 |bibcode=2019TEcoE..34..856B |hdl=10468/8068 |s2cid=174811556 |issn=0169-5347}}</ref>