Editing Archaeopteryx (section)

== Classification ==
[[File:Thermopolis Archaeopteryx.jpg|thumb|left|The Thermopolis Specimen]]
Today, fossils of the genus ''Archaeopteryx'' are usually assigned to one or two species, ''A. lithographica'' and ''A. siemensii'', but their taxonomic history is complicated. Ten names have been published for the handful of specimens. As interpreted today, the name ''A. lithographica'' only referred to the single feather described by [[Christian Erich Hermann von Meyer|Meyer]]. In 1954 [[Gavin de Beer]] concluded that the London specimen was the [[holotype]]. In 1960, Swinton accordingly proposed that the name ''Archaeopteryx lithographica'' be placed on the official genera list making the alternative names ''Griphosaurus'' and ''Griphornis'' invalid.<ref name=Swinton/> The [[ICZN]], implicitly accepting De Beer's standpoint, did indeed suppress the plethora of alternative names initially proposed for the first skeleton specimens,<ref name=ICZN_1961/> which mainly resulted from the acrimonious dispute between Meyer and his opponent [[Johann Andreas Wagner]] (whose ''Griphosaurus problematicus''—'problematic [[riddle]]-lizard'—was a vitriolic sneer at Meyer's ''Archaeopteryx'').<ref name=Wagner_1/> In addition, in 1977, the Commission ruled that the first species name of the Haarlem specimen, ''crassipes'', described by Meyer as a [[pterosaur]] before its true nature was realized, was not to be given preference over ''lithographica'' in instances where scientists considered them to represent the same species.<ref name=UCal_MoP/><ref name=ICZN_1977/>

It has been noted that the feather, the first specimen of ''Archaeopteryx'' described, does not correspond well with the flight-related feathers of ''Archaeopteryx''. It certainly is a [[flight feather]] of a contemporary species, but its size and proportions indicate that it may belong to another, smaller species of [[feathered dinosaur|feathered theropod]], of which only this feather is known so far.<ref name=Griffiths/> As the feather had been designated the [[Biological type|type specimen]], the name ''Archaeopteryx'' should then no longer be applied to the skeletons, thus creating significant [[International Code of Zoological Nomenclature|nomenclatorial]] confusion. In 2007, two sets of scientists therefore petitioned the ICZN requesting that the London specimen explicitly be made the type by designating it as the new holotype specimen, or [[neotype]].<ref name="icznneotype">{{Cite journal |last1=Bock |first1=W. J. |last2=Bühler |first2=P. |year=2007 |title=''Archaeopteryx lithographica'' von Meyer, 1861 (Aves): proposed conservation of usage by designation of a neotype |url=http://iczn.org/content/archaeopteryx-lithographica-von-meyer-1861-aves-proposed-conservation-usage-designation-neot |journal=Bulletin of Zoological Nomenclature |volume=64 |issue=4 |pages=261–262 |archive-date=6 March 2012 |access-date=8 January 2011 |archive-url=https://web.archive.org/web/20120306012804/http://iczn.org/content/archaeopteryx-lithographica-von-meyer-1861-aves-proposed-conservation-usage-designation-neot |url-status=live }}</ref> This suggestion was upheld by the ICZN after four years of debate, and the London specimen was designated the neotype on 3 October 2011.<ref name="icznneotypeconfirmed">{{Cite journal |last=ICZN |year=2011 |title=OPINION 2283 (Case 3390) Archaeopteryx lithographica von Meyer, 1861 (Aves): conservation of usage by designation of a neotype |url=http://iczn.org/content/opinion-2283-case-3390-archaeopteryx-lithographica-von-meyer-1861-aves-conservation-usage-de |journal=Bulletin of Zoological Nomenclature |volume=68 |issue=3 |pages=230–233 |doi=10.21805/bzn.v68i3.a16 |s2cid=160784119 |archive-date=18 March 2012 |access-date=7 October 2011 |archive-url=https://web.archive.org/web/20120318171909/http://iczn.org/content/opinion-2283-case-3390-archaeopteryx-lithographica-von-meyer-1861-aves-conservation-usage-de |url-status=live }}</ref>
[[File:Twelfth Archaeopteryx specimen.jpg|thumb|The twelfth specimen]]
Below is a [[cladogram]] published in 2013 by [[Pascal Godefroit|Godefroit]] ''et al.''<ref name="pascal"/>

{{clade| style=font-size:100%; line-height:100%
|label1=[[Avialae]]
|1={{clade
   |1=''[[Aurornis]]'' [[File:Aurornis.jpg|50 px]]
   |2={{clade
      |1=''[[Anchiornis]]''  [[File:Anchiornis_martyniuk.png|50 px]]
      |2={{clade
         |1='''''Archaeopteryx'''''  [[File:Archaeopteryx UDL.png|50 px]]
         |2={{clade
            |1=''[[Xiaotingia]]''  [[File:Xiaotingia .jpg|50 px]]
            |2={{clade
               |1={{clade
                  |1=''[[Jeholornis]]''  [[File:Jeholornis_mmartyniuk_wiki.jpg|50 px]]
                  |2=''[[Rahonavis]]''   [[File:Rahonavis NT.jpg|50 px]]}}
               |2={{clade
                  |1=''[[Balaur (dinosaur)|Balaur]]''  [[File:Balaur by Mark P. Witton.png|50 px]]
                  |2={{clade
                     |1=[[Avebrevicauda]] (includes modern birds)  [[File:Confuciusornis sanctus mmartyniuk.png|50 px]]}} }} }} }} }} }} }} }}

=== Species ===
[[File:Archaeopteryx skeletals.jpg|thumb|upright=2|Skeletal restorations of various specimens]]
It has been argued that all the specimens belong to the same species, ''A. lithographica''.<ref name=New_Scientist_1/> Differences do exist among the specimens, and while some researchers regard these as due to the different ages of the specimens, some may be related to actual species diversity. In particular, the Munich, Eichstätt, Solnhofen, and Thermopolis specimens differ from the London, Berlin, and Haarlem specimens in being smaller or much larger, having different finger proportions, having more slender snouts lined with forward-pointing teeth, and the possible presence of a [[sternum]]. Due to these differences, most individual specimens have been given their own species name at one point or another. The Berlin specimen has been designated as ''Archaeornis siemensii'', the Eichstätt specimen as ''Jurapteryx recurva'', the Munich specimen as ''Archaeopteryx bavarica'', and the Solnhofen specimen as ''Wellnhoferia grandis''.<ref name=Elzanowski2002/>

In 2007, a review of all well-preserved specimens including the then-newly discovered Thermopolis specimen concluded that two distinct species of ''Archaeopteryx'' could be supported: ''A. lithographica'' (consisting of at least the London and Solnhofen specimens), and ''A. siemensii'' (consisting of at least the Berlin, Munich, and Thermopolis specimens). The two species are distinguished primarily by large flexor [[Tubercle (bone)|tubercles]] on the foot claws in ''A. lithographica'' (the claws of ''A. siemensii'' specimens being relatively simple and straight). ''A. lithographica'' also had a constricted portion of the crown in some teeth and a stouter metatarsus. A supposed additional species, ''Wellnhoferia grandis'' (based on the Solnhofen specimen), seems to be indistinguishable from ''A. lithographica'' except in its larger size.<ref name=10th_find/>

=== Synonyms ===
[[File:Eichstätt Wellnhoferia grandis.jpg|thumb|upright|The Solnhofen Specimen, by some considered as belonging to the genus ''[[Wellnhoferia]]'']]
If two names are given, the first denotes the original describer of the "species", the second the author on whom the given name combination is based. As always in [[zoological nomenclature]], putting an author's name in parentheses denotes that the [[taxon]] was originally described in a different genus.
* '''''Archaeopteryx lithographica''''' Meyer, 1861 <small>[conserved name]</small>
**''Archaeopterix lithographica'' Anon., 1861 <small>[''lapsus'']</small>
** ''Griphosaurus problematicus'' Wagner, 1862 <small>[rejected name 1961 per ICZN Opinion 607]</small>
** ''Griphornis longicaudatus'' Owen ''vide'' Woodward, 1862 <small>[rejected name 1961 per ICZN Opinion 607]</small>
** ''Archaeopteryx macrura'' Owen, 1862 <small>[rejected name 1961 per ICZN Opinion 607]</small>
** ''Archaeopteryx oweni'' Petronievics, 1917 <small>[rejected name 1961 per ICZN Opinion 607]</small>
** ''Archaeopteryx recurva'' Howgate, 1984
** ''Jurapteryx recurva'' (Howgate, 1984) Howgate, 1985
** ''Wellnhoferia grandis'' Elżanowski, 2001
* '''''Archaeopteryx siemensii''''' Dames, 1897
**''Archaeornis siemensii'' (Dames, 1897) Petronievics, 1917<ref name=10th_find/>
** ''Archaeopteryx bavarica'' Wellnhofer, 1993

''"Archaeopteryx" vicensensis'' (Anon. ''fide'' Lambrecht, 1933) is a ''[[nomen nudum]]'' for what appears to be an undescribed pterosaur.

=== 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"/>