Editing Archaeopteryx (section)

=== Phylogenetic position ===
[[File:Archaeo-deinony hands.svg|thumb|upright|alt=Outline of bones in forelimbs of Deinonychus and Archaeopteryx; both have two fingers and an opposed claw with very similar layout, although Archaeopteryx has thinner bones|Comparison of the forelimb of ''Archaeopteryx'' (right) with that of ''[[Deinonychus]]'' (left)]]

Modern palaeontology has often classified ''Archaeopteryx'' as the most primitive bird. However, it is not thought to be a true ancestor of modern birds, but rather a close relative of that ancestor.<ref name="Clarke&Norell2002"/> Nonetheless, ''Archaeopteryx'' was often used as a model of the true ancestral bird. Several authors have done so.<ref name=Witmer02/> Lowe (1935)<ref name=Lowe_1935/> and Thulborn (1984)<ref name=Thulborn_1984/> questioned whether ''Archaeopteryx'' truly was the first bird. They suggested that ''Archaeopteryx'' was a dinosaur that was no more closely related to birds than were other dinosaur groups. Kurzanov (1987) suggested that ''[[Avimimus]]'' was more likely to be the ancestor of all birds than ''Archaeopteryx''.<ref name=Kurzanov_1987/> Barsbold (1983)<ref name=Barsbold_1983/> and Zweers and Van den Berge (1997)<ref name="Zweers&VandenBerge1997"/> noted that many [[maniraptora]]n lineages are extremely birdlike, and they suggested that different groups of birds may have descended from different dinosaur ancestors.

The discovery of the closely related ''[[Xiaotingia]]'' in 2011 led to new phylogenetic analyses that suggested that ''Archaeopteryx'' is a [[deinonychosaur]] rather than an avialan, and therefore, not a "bird" under most common uses of that term.<ref name="Xiaotingia"/> A more thorough analysis was published soon after to test this hypothesis, and failed to arrive at the same result; it found ''Archaeopteryx'' in its traditional position at the base of ''Avialae'', while ''Xiaotingia'' was recovered as a basal dromaeosaurid or troodontid. The authors of the follow-up study noted that uncertainties still exist, and that it may not be possible to state confidently whether or not ''Archaeopteryx'' is a member of Avialae or not, barring new and better specimens of relevant species.<ref name="leeetal2011">{{Cite journal |last1=Lee |first1=M. S. |last2=Worthy |first2=T. H. |year=2012 |title=Likelihood reinstates ''Archaeopteryx'' as a primitive bird |journal=Biology Letters |volume=8 |issue=2 |pages=299–303 |doi=10.1098/rsbl.2011.0884 |pmc=3297401 |pmid=22031726}}</ref>

Phylogenetic studies conducted by Senter, ''et al.'' (2012) and Turner, Makovicky, and Norell (2012) also found ''Archaeopteryx'' to be more closely related to living birds than to dromaeosaurids and troodontids.<ref>{{Cite journal |last1=Senter |first1=Phil |last2=Kirkland, James I. |last3=DeBlieux, Donald D. |last4=Madsen, Scott |last5=Toth, Natalie |year=2012 |editor-last=Dodson |editor-first=Peter |title=New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail |journal=PLOS ONE |volume=7 |issue=5 |pages=e36790 |bibcode=2012PLoSO...736790S |doi=10.1371/journal.pone.0036790 |pmc=3352940 |pmid=22615813 |doi-access=free}}</ref><ref name="TurneretalBAMNH">{{Cite journal |last1=Turner |first1=Alan H. |last2=Makovicky |first2=Peter J. |last3=Norell |first3=Mark A. |year=2012 |title=A review of dromaeosaurid systematics and paravian phylogeny |url=http://digitallibrary.amnh.org/bitstream/2246/6352/5/B371-cover.pdf |archive-url= https://ghostarchive.org/archive/20221009/http://digitallibrary.amnh.org/bitstream/2246/6352/5/B371-cover.pdf |archive-date=9 October 2022 |url-status=live |journal=Bulletin of the American Museum of Natural History |volume=371 |pages=1–206 |doi=10.1206/748.1 |hdl=2246/6352 |s2cid=83572446}}</ref> On the other hand, Godefroit ''et al.'' (2013) recovered ''Archaeopteryx'' as more closely related to dromaeosaurids and troodontids in the analysis included in their description of ''[[Eosinopteryx |Eosinopteryx brevipenna]]''. The authors used a modified version of the matrix from the study describing ''Xiaotingia'', adding ''[[Jinfengopteryx |Jinfengopteryx elegans]]'' and ''Eosinopteryx brevipenna'' to it, as well as adding four additional characters related to the development of the plumage. Unlike the analysis from the description of ''Xiaotingia'', the analysis conducted by Godefroit, ''et al.'' did not find ''Archaeopteryx'' to be related particularly closely to ''Anchiornis'' and ''Xiaotingia'', which were recovered as basal troodontids instead.<ref>{{Cite journal |last1=Godefroit |first1=P |last2=Demuynck |first2=H |last3=Dyke |first3=G |last4=Hu |first4=D |last5=Escuillié |first5=F |last6=Claeys |first6=P |year=2013 |title=Reduced plumage and flight ability of a new Jurassic paravian theropod from China |journal=Nature Communications |volume=4 |pages=Article number 1394 |bibcode=2013NatCo...4.1394G |doi=10.1038/ncomms2389 |pmid=23340434 |doi-access=free}}</ref>

Agnolín and Novas (2013) found ''Archaeopteryx'' and (possibly synonymous) ''[[Wellnhoferia]]'' to form a clade sister to the lineage including ''Jeholornis'' and Pygostylia, with [[Microraptoria]], [[Unenlagiinae]], and the clade containing ''Anchiornis'' and ''Xiaotingia'' being successively closer outgroups to the Avialae (defined by the authors as the clade stemming from the last common ancestor of ''Archaeopteryx'' and Aves).<ref name="avianancestry">{{Cite book |last1=Agnolin |first1=Federico |title=Avian ancestors. A review of the phylogenetic relationships of the theropods Unenlagiidae, Microraptoria, ''Anchiornis'', and Scansoriopterygidae |last2=Novas |first2=Fernando E |year=2013 |isbn=978-94-007-5636-6 |series=SpringerBriefs in Earth System Sciences |pages=1–96 |doi=10.1007/978-94-007-5637-3 |s2cid=199493087}}</ref> Another phylogenetic study by Godefroit, ''et al.'', using a more inclusive matrix than the one from the analysis in the description of ''Eosinopteryx brevipenna'', also found ''Archaeopteryx'' to be a member of Avialae (defined by the authors as the most inclusive clade containing ''[[house sparrow|Passer domesticus]]'', but not ''[[Dromaeosaurus |Dromaeosaurus albertensis]]'' or ''[[Troodon |Troodon formosus]]''). ''Archaeopteryx'' was found to form a [[Evolutionary grade|grade]] at the base of Avialae with ''Xiaotingia'', ''Anchiornis'', and ''[[Aurornis]]''. Compared to ''Archaeopteryx'', ''Xiaotingia'' was found to be more closely related to extant birds, while both ''Anchiornis'' and ''[[Aurornis]]'' were found to be more distantly so.<ref name="pascal"/>

Hu ''et al''. (2018),<ref>{{Cite journal |last1=Hu |first1=Dongyu |last2=Clarke |first2=Julia A. |last3=Eliason |first3=Chad M. |last4=Qiu |first4=Rui |last5=Li |first5=Quanguo |last6=Shawkey |first6=Matthew D. |last7=Zhao |first7=Cuilin |last8=D’Alba |first8=Liliana |last9=Jiang |first9=Jinkai |last10=Xu |first10=Xing |date=15 January 2018 |title=A bony-crested Jurassic dinosaur with evidence of iridescent plumage highlights complexity in early paravian evolution |journal=Nature Communications |language=en |volume=9 |issue=1 |pages=217 |bibcode=2018NatCo...9..217H |doi=10.1038/s41467-017-02515-y |issn=2041-1723 |pmc=5768872 |pmid=29335537 |doi-access=free}}</ref> Wang ''et al''. (2018)<ref>{{Cite journal |last1=Wang |first1=Min |last2=O’Connor |first2=Jingmai K. |last3=Xu |first3=Xing |last4=Zhou |first4=Zhonghe |date=May 2019 |title=A new Jurassic scansoriopterygid and the loss of membranous wings in theropod dinosaurs |url=http://www.nature.com/articles/s41586-019-1137-z |journal=Nature |language=en |volume=569 |issue=7755 |pages=256–259 |bibcode=2019Natur.569..256W |doi=10.1038/s41586-019-1137-z |issn=0028-0836 |pmid=31068719 |s2cid=148571099 |archive-date=8 January 2021 |access-date=11 January 2021 |archive-url=https://web.archive.org/web/20210108062142/https://www.nature.com/articles/s41586-019-1137-z |url-status=live }}</ref> and Hartman ''et al''. (2019)<ref name=":1">{{Cite journal|last1=Hartman |first1=Scott |last2=Mortimer |first2=Mickey |last3=Wahl |first3=William R. |last4=Lomax |first4=Dean R. |last5=Lippincott |first5=Jessica |last6=Lovelace |first6=David M. |date=10 July 2019 |title=A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight |journal=PeerJ |volume=7 |pages=e7247 |doi=10.7717/peerj.7247 |issn=2167-8359 |pmc=6626525 |pmid=31333906 |doi-access=free }}</ref> found ''Archaeopteryx'' to have been a deinonychosaur instead of an avialan. More specifically, it and closely related taxa were considered basal deinonychosaurs, with dromaeosaurids and troodontids forming together a parallel lineage within the group. Because Hartman ''et al''. found ''Archaeopteryx'' isolated in a group of flightless deinonychosaurs (otherwise considered "[[Anchiornithidae|anchiornithids]]"), they considered it highly probable that this animal [[Convergent evolution|evolved flight independently]] from bird ancestors (and from ''Microraptor'' and ''[[Yi (dinosaur)|Yi]]''). The following cladogram illustrates their hypothesis regarding the position of ''Archaeopteryx'':

{{clade
|1=[[Oviraptorosauria]]
|label2=[[Paraves]]
|2={{clade
   |1=[[Avialae]]
   |label2=[[Deinonychosauria]]
   |2={{clade
      |1={{clade
         |1=[[Unenlagiidae]]
         |2={{clade
            |1=[[Dromaeosauridae]]
            |2=[[Troodontidae]] }} }}
      |label2='''Archaeopterygidae''' (=[[Anchiornithidae]])
      |2={{clade
         |1=''[[Serikornis]]''
         |2={{clade
            |1=''[[Caihong]]''
            |2={{clade
               |1=''[[Anchiornis]]''
               |2={{clade
                  |1='''''Archaeopteryx'''''
                  |2={{clade
                     |1=''[[Eosinopteryx]]''
                     |2=''[[Aurornis]]''
}} }} }} }} }} }} }} }}
The authors, however, found that the ''Archaeopteryx'' being an avialan was only slightly less likely than this hypothesis, and as likely as Archaeopterygidae and Troodontidae being sister clades.<ref name=":1"/>