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went ahead and made some major updates to the article. Added some sources and info, cleaned up the classification a bit, and removed some unnecessary stuff
expanded display parents, moved the incertae sedis genera from the taxobox to down in the text of the article, and grabbed placoderm evolution picture from the Placodermi page
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| image = D_Terrelli.png
| image = D_Terrelli.png
| image_caption = Artist's reconstruction of the arthrodire placoderm ''[[Dunkleosteus terrelli]]''
| image_caption = Artist's reconstruction of the arthrodire placoderm ''[[Dunkleosteus terrelli]]''
| display_parents = 2
| taxon = Arthrodira
| taxon = Arthrodira
| authority = Woodward, 1891
| authority = Woodward, 1891
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* [[Wuttagoonaspidae]]
* [[Wuttagoonaspidae]]
* Genera ''[[incertae sedis]]''
* Genera ''[[incertae sedis]]''
** see [[Arthrodira#Classification|text]] for list
** ''[[Aethaspis]]''
** ''[[Aleosteus]]''
** ''[[Anarthraspis]]''
** ''[[Antarctaspis]]''
** ''[[Antarctolepis]]''
** ''[[Aspidichthys]]''
** ''[[Baringaspis]]''
** ''[[Bryantolepis]]''
** ''[[Callognathus]]''
** ''[[Copanognathus]]''
** ''[[Carolowilhelmina]]''
** ''[[Diplognathus]]''
** ''[[Erikaspis]]''
** ''[[Eskimaspis]]''
** ''[[Glyptaspis]]''
** ''[[Grazosteus]]''
** ''[[Heightingtonaspis]]''
** ''[[Hollardosteus]]''
** ''[[Kujdanowiaspis]]''
** ''[[Lataspis]]''
** ''[[Laurentaspis]]''
** ''[[Lehmanosteus]]''
** ''[[Machaerognathus]]''
** ''[[Maideria]]''
** ''[[Mediaspis]]''
** ''[[Murmur (placoderm)|Murmur]]''
** ''[[Overtonaspis]]''
** ''[[Phylactaenium]]''
** ''[[Pinguosteus]]''
** ''[[Prescottaspis]]''
** ''[[Proaethaspis]]''
** ''[[Qataraspis]]''
** ''[[Sigaspis]]''
** ''[[Simblaspis]]''
** ''[[Taunaspis]]''
** ''[[Timanosteus]]''
** ''[[Trachosteus]]''
** ''[[Wheathillaspis]]''
** ''[[Yujiangolepis]]''
}}
}}


'''Arthrodira''' (Greek for "jointed neck") is an [[Order (biology)|order]] of [[extinct]] armored, jawed fishes of the class [[Placodermi]] that flourished in the [[Devonian]] period before their sudden extinction, surviving for about 50 million years and penetrating most marine [[ecological niche]]s. Arthrodires were the largest and most diverse of all groups of Placoderms.<ref name=Zhu2016>{{Cite journal |last1=Zhu |first1=You-An |last2=Zhu |first2=Min |last3=Wang |first3=Jun-Qing |date=1 April 2016 |title=Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci |journal=[[Zoological Journal of the Linnean Society]] |volume=176 |issue=4 |pages=806–834 |doi=10.1111/zoj.12356|issn=0024-4082 |doi-access=free }}</ref>
'''Arthrodira''' (Greek for "jointed neck") is an [[Order (biology)|order]] of [[extinct]] armored, jawed fishes of the class [[Placodermi]] that flourished in the [[Devonian]] period before their sudden extinction, surviving for about 50 million years and penetrating most marine [[ecological niche]]s. Arthrodires were the largest and most diverse of all groups of Placoderms.<ref name=Zhu2016>{{Cite journal |last1=Zhu |first1=You-An |last2=Zhu |first2=Min |last3=Wang |first3=Jun-Qing |date=1 April 2016 |title=Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci |journal=[[Zoological Journal of the Linnean Society]] |volume=176 |issue=4 |pages=806–834 |doi=10.1111/zoj.12356|issn=0024-4082 |doi-access=free }}</ref>
[[File:C cuspidatus.png|thumb|left|Artist's reconstruction of the arthrodire placoderm ''[[Coccosteus cuspidatus]]'']]
[[File:Eastmanosteus pustulosus.jpg|thumb|220px|upright|left|Lower jaw plate of ''[[Eastmanosteus pustulosus]]'' from the [[Middle Devonian]] of [[Wisconsin]]]]
[[Image:Heterosteus ingens.jpg|thumb|upright|left|''[[Heterosteus ingens]]'' from the [[Middle Devonian]] of [[Estonia]]]]


==Description==
==Description==
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A common misconception is the arthrodires (along with all other placoderms) were sluggish bottom-dwellers that were outcompeted by more advanced fish. Leading to this misconception is that the arthrodire [[body plan]] remained relatively conserved (that is, the majority of arthrodires were [[bullet]]- or [[torpedo]]-shaped) during the Devonian period, save for increasing in size. However, during their reign, the arthrodires were one of the most diverse and numerically successful, if not the most successful, vertebrate orders of the Devonian, occupying a vast spectrum of roles from [[apex predator]] to [[detritus]]-nibbling [[bottom dweller]]. Despite their success, the arthrodires were one of many groups eliminated by the environmental catastrophes of the [[Late Devonian extinction]], allowing other fish such as [[shark]]s to diversify into the vacated ecological niches during the [[Carboniferous]] period.{{fact|date=August 2021}}
A common misconception is the arthrodires (along with all other placoderms) were sluggish bottom-dwellers that were outcompeted by more advanced fish. Leading to this misconception is that the arthrodire [[body plan]] remained relatively conserved (that is, the majority of arthrodires were [[bullet]]- or [[torpedo]]-shaped) during the Devonian period, save for increasing in size. However, during their reign, the arthrodires were one of the most diverse and numerically successful, if not the most successful, vertebrate orders of the Devonian, occupying a vast spectrum of roles from [[apex predator]] to [[detritus]]-nibbling [[bottom dweller]]. Despite their success, the arthrodires were one of many groups eliminated by the environmental catastrophes of the [[Late Devonian extinction]], allowing other fish such as [[shark]]s to diversify into the vacated ecological niches during the [[Carboniferous]] period.{{fact|date=August 2021}}


[[File:Evolution of placoderms.png|thumb|260px|left|Evolution and extinction of [[placoderms]]. The diagram is based on [[Michael Benton]], 2005.<ref name="Benton, M. J. 2005 page 73">Benton, M. J. (2005) Vertebrate Palaeontology, Blackwell, 3rd edition, Figure 3.25 on page 73.</ref>]]
==Systematics==

[[File:C cuspidatus.png|thumb|right|Artist's reconstruction of the arthrodire placoderm ''[[Coccosteus cuspidatus]]'']]
[[File:Eastmanosteus pustulosus.jpg|thumb|right|220px|upright|Lower jaw plate of ''[[Eastmanosteus pustulosus]]'' from the [[Middle Devonian]] of [[Wisconsin]]]]
[[Image:Heterosteus ingens.jpg|thumb|right|upright|''[[Heterosteus ingens]]'' from the [[Middle Devonian]] of [[Estonia]]]]

==Phylogeny==
The [[order (biology)|order]] Arthrodira belongs to the [[Class (biology)|class]] [[Placodermi]], the large group of extinct prehistoric armored fish that is thought to have diverged over 400 million years ago from all [[sharks]] and [[bony fishes]] (and thus also all subsequent [[tetrapods]], including mammals, birds, reptiles and amphibians). However, recent [[phylogenetic]] studies have found Placodermi to be [[paraphyletic]], and rather an [[evolutionary grade]] towards [[Eugnathostomata]], the [[clade]] grouping that contains sharks and bony fish and all tetrapods.<ref name="Giles et al 2015">{{closed access}} {{cite journal |last1=Giles |first1=Sam |last2=Friedman |first2=Matt |last3=Brazeau |first3=Martin D. |title=Osteichthyan-like cranial conditions in an Early Devonian stem gnathostome |journal=[[Nature (journal)|Nature]] |volume=520 |issue=7545 |pages=82–85 |date=2015-01-12 |issn=1476-4687 |doi=10.1038/nature14065 |pmid=25581798 |pmc=5536226 |bibcode=2015Natur.520...82G }}</ref><ref name=zhu2016B>{{cite journal |last1=Zhu |first1=Min |last2=Ahlberg |first2=Per E. |last3=Pan |first3=Zhaohui |last4=Zhu |first4=Youan |last5=Qiao |first5=Tuo |last6=Zhao |first6=Wenjin |last7=Jia |first7=Liantao |last8=Lu |first8=Jing |title=A Silurian maxillate placoderm illuminates jaw evolution |journal=Science |date=21 October 2016 |volume=354 |issue=6310 |pages=334–336 |doi=10.1126/science.aah3764 |pmid=27846567 |bibcode=2016Sci...354..334Z |s2cid=45922669 }}</ref>

Arthrodira was traditionally divided into the [[paraphyletic]] [[Actinolepida]], the [[Phlyctaenii]] (now also paraphyletic), and the [[Brachythoraci]].<ref name=Zhu2013>{{Cite journal |author1=You-An Zhu |author2=Min Zhu |title=A redescription of Kiangyousteus yohii (Arthrodira: Eubrachythoraci) from the Middle Devonian of China, with remarks on the systematics of the Eubrachythoraci | journal=[[Zoological Journal of the Linnean Society]] |volume=169 |issue=4 |pages=798-819 |year=2013 |doi=10.1111/zoj12089 |doi-access=free }}</ref> [[Phylogenetic]] studies have since found two of those groups as paraphyletic, as shown in the [[cladogram]] below, from Dupret ''et al.'' (2009).<ref name=DZW09>{{Cite journal | last1 = Dupret | first1 = V. | last2 = Zhu | first2 = M. I. N. | last3 = Wang | first3 = J. N. Q. | title = The morphology of ''Yujiangolepis liujingensis'' (Placodermi, Arthrodira) from the Pragian of Guangxi (south China) and its phylogenetic significance | doi = 10.1111/j.1096-3642.2009.00519.x | journal = Zoological Journal of the Linnean Society | volume = 157 |page=70 | year = 2009 | doi-access = free }}</ref>
Arthrodira was traditionally divided into the [[paraphyletic]] [[Actinolepida]], the [[Phlyctaenii]] (now also paraphyletic), and the [[Brachythoraci]].<ref name=Zhu2013>{{Cite journal |author1=You-An Zhu |author2=Min Zhu |title=A redescription of Kiangyousteus yohii (Arthrodira: Eubrachythoraci) from the Middle Devonian of China, with remarks on the systematics of the Eubrachythoraci | journal=[[Zoological Journal of the Linnean Society]] |volume=169 |issue=4 |pages=798-819 |year=2013 |doi=10.1111/zoj12089 |doi-access=free }}</ref> [[Phylogenetic]] studies have since found two of those groups as paraphyletic, as shown in the [[cladogram]] below, from Dupret ''et al.'' (2009).<ref name=DZW09>{{Cite journal | last1 = Dupret | first1 = V. | last2 = Zhu | first2 = M. I. N. | last3 = Wang | first3 = J. N. Q. | title = The morphology of ''Yujiangolepis liujingensis'' (Placodermi, Arthrodira) from the Pragian of Guangxi (south China) and its phylogenetic significance | doi = 10.1111/j.1096-3642.2009.00519.x | journal = Zoological Journal of the Linnean Society | volume = 157 |page=70 | year = 2009 | doi-access = free }}</ref>


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==Classification==
Order '''Arthrodira''' <small>Woodward, 1891</small>
* [[Phlyctaenioidei]] <small>Miles, 1973</small>
** [[Brachythoraci]] <small>Gross, 1932</small> (includes the well-known ''[[Dunkleosteus]]'', ''[[Dinichthys]]'', etc.)
** [[Williamsaspididae]] <small>White, 1952</small>
** [[Groenlandaspididae]] <small>Obruchev, 1964</small>
** [[Arctolepididae]] <small>Stensiö, 1959</small>
** [[Phlyctaeniidae]] <small>Fowler, 1947</small>
* [[Actinolepidae]] <small>Gross, 1940</small>
* [[Phyllolepida]] <small>Stensiö 1934</small>
* [[Wuttagoonaspidae]] <small>Ritchie 1973</small>
* Genera ''[[incertae sedis]]''
** ''[[Aethaspis]]'' <small>Denison, 1958</small> (may be within [[Actinolepidae]])
** ''[[Aleosteus]]'' <small> Johnson ''et al.'', 2000</small> (may be within [[Actinolepidae]])
** ''[[Anarthraspis]]'' <small>Bryant, 1934</small> (may be within [[Actinolepidae]])
** ''[[Antarctaspis]]'' <small>White, 1968</small> (previously within [[Antarctaspididae]])
** ''[[Antarctolepis]]'' <small>White, 1968</small>
** ''[[Aspidichthys]]'' <small>Newberry, 1873</small>
** ''[[Baringaspis]]'' <small>Miles, 1973</small> (may be within [[Actinolepidae]])
** ''[[Bryantolepis]]'' <small>Denison, 1958</small> (may be within [[Actinolepidae]])
** ''[[Callognathus]]'' <small>Newberry, 1890</small>
** ''[[Copanognathus]]'' <small>Hussakof & Bryant, 1920</small>
** ''[[Carolowilhelmina]]'' <small>Mark-Kurik & Carls, 2002</small>
** ''[[Diplognathus]]'' <small>Newberry, 1878</small>
** ''[[Erikaspis]]'' <small>Dupret, Goujet, & Mark-Kurik, 2007</small>
** ''[[Eskimaspis]]'' <small>Dineley & Yuhai, 1984</small>
** ''[[Glyptaspis]]'' <small>Newberry, 1890</small>
** ''[[Grazosteus]]'' <small>Gross, 1958</small>
** ''[[Heightingtonaspis]]'' <small>White, 1969</small> (may be within [[Actinolepidae]])
** ''[[Hollardosteus]]'' <small>Lehman, 1956</small>
** ''[[Kujdanowiaspis]]'' <small>Stensiö, 1942</small> (may be within [[Actinolepidae]])
** ''[[Lataspis]]'' <small>Strand, 1932</small> (may be within [[Actinolepidae]])
** ''[[Laurentaspis]]'' <small>Pageau, 1969</small>
** ''[[Lehmanosteus]]'' <small>Goujet, 1984</small> (may be within [[Actinolepidae]])
** ''[[Machaerognathus]]'' <small>Hussakof & Bryant, 1919</small>
** ''[[Maideria]]'' <small>Lelièvre, 1995</small>
** ''[[Mediaspis]]'' <small>Heintz, 1929</small> (may be within [[Actinolepidae]])
** ''[[Murmur (placoderm)|Murmur]]'' <small>Whitley, 1951</small>
** ''[[Overtonaspis]]'' <small>White, 1961</small>
** ''[[Phylactaenium]]'' <small>Heintz, 1934</small>
** ''[[Pinguosteus]]'' <small>Long, 1990</small> (may be within [[Brachythoraci]])
** ''[[Prescottaspis]]'' <small>White, 1961</small>
** ''[[Proaethaspis]]'' <small>Denison, 1978</small> (may be within [[Actinolepidae]])
** ''[[Qataraspis]]'' <small>White, 1969</small>
** ''[[Sigaspis]]'' <small>Goujet, 1973</small> (may be within [[Actinolepidae]])
** ''[[Simblaspis]]'' <small>Denison, 1958</small> (may be within [[Actinolepidae]])
** ''[[Taunaspis]]'' <small>Schmidt, 1933</small>
** ''[[Timanosteus]]'' <small>Obrucheva, 1962</small>
** ''[[Trachosteus]]'' <small>Newberry, 18903</small> (may be within [[Coccosteidae]])
** ''[[Wheathillaspis]]'' <small>White, 1961</small>
** ''[[Yujiangolepis]]'' <small>Wang & Dupret, 2009</small> (previously within [[Antarctaspididae]])


==References==
==References==

Revision as of 21:55, 18 October 2022

Arthrodira
Temporal range: Devonian, 419.2–358.9 Ma
Artist's reconstruction of the arthrodire placoderm Dunkleosteus terrelli
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Infraphylum: Gnathostomata
Class: †Placodermi
Order: †Arthrodira
Woodward, 1891
Subgroups

Arthrodira (Greek for "jointed neck") is an order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches. Arthrodires were the largest and most diverse of all groups of Placoderms.[1]

Description

Arthrodire placoderms are notable for the movable joint between armor surrounding their heads and bodies. Like all placoderms, they lacked distinct teeth; instead, they used the sharpened edges of a bony plate on their jawbone as a biting surface. The eye sockets are protected by a bony ring, a feature shared by birds and some ichthyosaurs. Early arthrodires, such as the genus Arctolepis, were well-armoured fishes with flattened bodies. The largest member of this group, Dunkleosteus, was a true superpredator of the latest Devonian period, reaching as much as 6 m in length. In contrast, the long-nosed Rolfosteus measured just 15 cm.[2] Fossils of Incisoscutum have been found containing unborn fetuses, indicating that arthrodires gave birth to live young.[3][4]

A common misconception is the arthrodires (along with all other placoderms) were sluggish bottom-dwellers that were outcompeted by more advanced fish. Leading to this misconception is that the arthrodire body plan remained relatively conserved (that is, the majority of arthrodires were bullet- or torpedo-shaped) during the Devonian period, save for increasing in size. However, during their reign, the arthrodires were one of the most diverse and numerically successful, if not the most successful, vertebrate orders of the Devonian, occupying a vast spectrum of roles from apex predator to detritus-nibbling bottom dweller. Despite their success, the arthrodires were one of many groups eliminated by the environmental catastrophes of the Late Devonian extinction, allowing other fish such as sharks to diversify into the vacated ecological niches during the Carboniferous period.[citation needed]

Evolution and extinction of placoderms. The diagram is based on Michael Benton, 2005.[5]
Artist's reconstruction of the arthrodire placoderm Coccosteus cuspidatus
Lower jaw plate of Eastmanosteus pustulosus from the Middle Devonian of Wisconsin
Heterosteus ingens from the Middle Devonian of Estonia

Phylogeny

The order Arthrodira belongs to the class Placodermi, the large group of extinct prehistoric armored fish that is thought to have diverged over 400 million years ago from all sharks and bony fishes (and thus also all subsequent tetrapods, including mammals, birds, reptiles and amphibians). However, recent phylogenetic studies have found Placodermi to be paraphyletic, and rather an evolutionary grade towards Eugnathostomata, the clade grouping that contains sharks and bony fish and all tetrapods.[6][7]

Arthrodira was traditionally divided into the paraphyletic Actinolepida, the Phlyctaenii (now also paraphyletic), and the Brachythoraci.[8] Phylogenetic studies have since found two of those groups as paraphyletic, as shown in the cladogram below, from Dupret et al. (2009).[9]

Lunaspis broilii

Eurycaraspis incilis

Arthrodira

Yujiangolepis liujingensis

Antarctaspis mcmurdoensis

Wuttagoonaspidae
Actinolepidoidei
Phlyctaeniina

Classification

Order Arthrodira Woodward, 1891

References

  1. ^ Zhu, You-An; Zhu, Min; Wang, Jun-Qing (1 April 2016). "Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci". Zoological Journal of the Linnean Society. 176 (4): 806–834. doi:10.1111/zoj.12356. ISSN 0024-4082.
  2. ^ Dennis, Kim, and R. S. Miles. "Eubrachythoracid arthrodires with tubular rostral plates from Gogo, Western Australia." Zoological Journal of the Linnean Society 67.4 (1979): 297–328.
  3. ^ "Fish 380 Million Years Old Found With Unborn Embryo". Science Daily. June 6, 2008.
  4. ^ Long, John A.; Trinajstic, Kate; Johanson, Zerina (26 February 2009). "Devonian arthrodire embryos and the origin of internal fertilization in vertebrates". Nature. 457: 1124–1127. doi:10.1038/nature07732.
  5. ^ Benton, M. J. (2005) Vertebrate Palaeontology, Blackwell, 3rd edition, Figure 3.25 on page 73.
  6. ^ Closed access icon Giles, Sam; Friedman, Matt; Brazeau, Martin D. (2015-01-12). "Osteichthyan-like cranial conditions in an Early Devonian stem gnathostome". Nature. 520 (7545): 82–85. Bibcode:2015Natur.520...82G. doi:10.1038/nature14065. ISSN 1476-4687. PMC 5536226. PMID 25581798.
  7. ^ Zhu, Min; Ahlberg, Per E.; Pan, Zhaohui; Zhu, Youan; Qiao, Tuo; Zhao, Wenjin; Jia, Liantao; Lu, Jing (21 October 2016). "A Silurian maxillate placoderm illuminates jaw evolution". Science. 354 (6310): 334–336. Bibcode:2016Sci...354..334Z. doi:10.1126/science.aah3764. PMID 27846567. S2CID 45922669.
  8. ^ You-An Zhu; Min Zhu (2013). "A redescription of Kiangyousteus yohii (Arthrodira: Eubrachythoraci) from the Middle Devonian of China, with remarks on the systematics of the Eubrachythoraci". Zoological Journal of the Linnean Society. 169 (4): 798–819. doi:10.1111/zoj12089.
  9. ^ Dupret, V.; Zhu, M. I. N.; Wang, J. N. Q. (2009). "The morphology of Yujiangolepis liujingensis (Placodermi, Arthrodira) from the Pragian of Guangxi (south China) and its phylogenetic significance". Zoological Journal of the Linnean Society. 157: 70. doi:10.1111/j.1096-3642.2009.00519.x.

Further Reading

  • Long, John A. (1996): The Rise of Fishes: 500 Million Years of Evolution. Johns Hopkins University Press, Baltimore. ISBN 0-8018-5438-5
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