Editing Tetrapod (section)

== Phylogeny ==

=== Stem group ===
[[Stem tetrapoda|Stem tetrapods]] are all animals more closely related to tetrapods than to lungfish, but excluding the tetrapod crown group. The cladogram below illustrates the relationships of stem-tetrapods. All these lineages are extinct except for Dipnomorpha and Tetrapoda; from Swartz, 2012:<ref name=SB12>{{cite journal | last = Swartz | first = B. | year = 2012 | title = A marine stem-tetrapod from the Devonian of Western North America | journal = PLOS ONE | pmid = 22448265 | volume = 7 | issue = 3 | pmc = 3308997 | pages = e33683 | doi = 10.1371/journal.pone.0033683 | bibcode = 2012PLoSO...733683S | doi-access = free }}</ref>  

{{clade| style=font-size:85%;line-height:85%
|label1=[[Rhipidistia]]
|1={{clade
|1=[[Dipnomorpha]] (lungfishes and relatives) [[File:Protopterus dolloi Boulenger2.jpg|70 px]]
|label2=[[Tetrapodomorpha]]
|2={{clade
   |1=''[[Kenichthys]]''
   |2={{clade
      |1=[[Rhizodontidae]] [[File:Gooloogongia loomesi reconstruction.jpg|70 px]]
      |2={{clade
         |label1=[[Canowindridae]]
         |1={{clade
            |1=''[[Marsdenichthys]]''
            |2={{clade
               |1=''[[Canowindra (fish)|Canowindra]]''
               |2={{clade
                  |1=''[[Koharalepis]]''
                  |2=''[[Beelarongia]]''}} }} }}
         |2={{clade
            |label1=[[Megalichthyiformes]]
            |1={{clade
               |1=''[[Gogonasus]]'' [[File:Gogonasus BW.jpg|70 px]]
               |2={{clade
                  |1=''[[Gyroptychius]]''
                  |2={{clade
                     |1=''[[Osteolepis]]'' [[File:Osteolepis BW.jpg|70 px]]
                     |2={{clade
                        |1=''[[Medoevia]]''
                        |2=[[Megalichthyidae]]}} }} }} }}
            |label2=[[Eotetrapodiformes]]
            |2={{clade
               |label1=[[Tristichopteridae]]
               |1={{clade
                  |1=''[[Spodichthys]]''
                  |2={{clade
                     |1=''[[Tristichopterus]]''
                     |2={{clade
                        |1=''[[Eusthenopteron]]'' [[File:Eusthenopteron BW.jpg|70 px]]
                        |2={{clade
                           |1=''[[Jarvikina]]''
                           |2={{clade
                              |1=''[[Cabbonichthys]]''
                              |2={{clade
                                 |1=''[[Mandageria]]''
                                 |2=''[[Eusthenodon]]''}} }} }} }} }} }}
               |2={{clade
                  |1=''[[Tinirau (fish)|Tinirau]]''
                  |2={{clade
                     |1=''[[Platycephalichthys]]''
                     |label2=[[Elpistostegalia]]
                     |2={{clade
                        |1=''[[Panderichthys]]'' [[File:Panderichthys BW.jpg|70 px]]
                        |label2=[[Stegocephalia]]
                        |2={{clade
                           |1={{clade
                              |1=''[[Tiktaalik]]'' [[File:Tiktaalik BW.jpg|70 px]]
                              |2=''[[Elpistostege]]''}}
                           |2={{clade
                              |1=''[[Elginerpeton]]'' [[File:Elginerpeton BW.jpg|70 px]]
                              |2={{clade
                                 |1=''[[Ventastega]]''
                                 |2={{clade
                                    |1=''[[Acanthostega]]'' [[File:Acanthostega BW.jpg|70 px]]
                                    |2={{clade
                                       |1=''[[Ichthyostega]]'' [[File:Ichthyostega BW.jpg|70 px]]
                                       |2={{clade
                                          |1=[[Whatcheeriidae]] [[File:Pederpes22small.jpg|70 px]]
                                          |2={{clade
                                             |1=[[Colosteidae]] [[File:Greererpeton BW.jpg|70 px]]
                                             |2={{clade
                                                |1=''[[Crassigyrinus]]'' [[File:Crassigyrinus BW.jpg|70 px]]
                                                |2={{clade
                                                   |1=[[Baphetidae]]
                                                   |2=Tetrapoda [[File:Seymouria BW.jpg|70 px]]
}} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }}

=== Crown group ===
Crown tetrapods are defined as the nearest common ancestor of all living tetrapods (amphibians, reptiles, birds, and mammals) along with all of the descendants of that ancestor.

The inclusion of certain extinct groups in the crown Tetrapoda depends on the relationships of modern amphibians, or [[lissamphibia]]ns. There are currently three major hypotheses on the origins of lissamphibians. In the temnospondyl hypothesis (TH), lissamphibians are most closely related to dissorophoid [[temnospondyl]]s, which would make temnospondyls tetrapods. In the lepospondyl hypothesis (LH), lissamphibians are the sister taxon of lysorophian [[lepospondyl]]s, making lepospondyls tetrapods and temnospondyls stem-tetrapods. In the polyphyletic hypothesis (PH), frogs and salamanders evolved from dissorophoid temnospondyls while caecilians come out of microsaur lepospondyls, making both lepospondyls and temnospondyls true tetrapods.<ref name="SigurdsenGreen2011">{{cite journal|last1=Sigurdsen|first1=Trond|last2=Green|first2=David M.|title=The origin of modern amphibians: a re-evaluation|journal=Zoological Journal of the Linnean Society|volume=162|issue=2|date=June 2011|pages=457–469|issn=0024-4082|doi=10.1111/j.1096-3642.2010.00683.x|doi-access=free}}</ref><ref name="Benton2014">{{cite book|last=Benton|first=Michael|author-link=Michael Benton|title=Vertebrate Palaeontology|url=https://books.google.com/books?id=qak-BAAAQBAJ&pg=PT398|access-date=2 July 2015|date=4 August 2014|publisher=Wiley|isbn=978-1-118-40764-6|page=398|archive-date=19 August 2020|archive-url=https://web.archive.org/web/20200819201052/https://books.google.com/books?id=qak-BAAAQBAJ&pg=PT398|url-status=live}}</ref>
=== Origins of modern amphibians ===
==== Temnospondyl hypothesis (TH) ====
This hypothesis comes in a number of variants, most of which have lissamphibians coming out of the dissorophoid temnospondyls, usually with the focus on amphibamids and branchiosaurids.<ref name="NarinsFeng2006">{{cite book|last1=Narins|first1=Peter M.|last2=Feng|first2=Albert S.|last3=Fay|first3=Richard R.|title=Hearing and Sound Communication in Amphibians|url=https://books.google.com/books?id=UPJcyY7TuiIC&pg=PA16|access-date=2 July 2015|date=11 December 2006|publisher=Springer Science & Business Media|isbn=978-0-387-47796-1|page=16|archive-date=20 August 2020|archive-url=https://web.archive.org/web/20200820000649/https://books.google.com/books?id=UPJcyY7TuiIC&pg=PA16|url-status=live}}</ref>

The temnospondyl hypothesis is the currently favored or majority view, supported by Ruta ''et al'' (2003a,b), Ruta and Coates (2007), Coates ''et al'' (2008), Sigurdsen and Green (2011), and Schoch (2013, 2014).<ref name="Benton2014"/><ref name="HedgesKumar2009">{{cite book|author1=S. Blair Hedges|author2=Sudhir Kumar|title=The Timetree of Life|url=https://books.google.com/books?id=9rt1c1hl49MC&pg=PA354|date=23 April 2009|publisher=OUP Oxford|isbn=978-0-19-156015-6|pages=354–|access-date=13 March 2016|archive-date=18 August 2020|archive-url=https://web.archive.org/web/20200818213648/https://books.google.com/books?id=9rt1c1hl49MC&pg=PA354|url-status=live}}</ref>

[[Cladogram]] modified after Coates, Ruta and Friedman (2008).<ref name="CoatesRuta2008">{{cite journal|last1=Coates|first1=Michael I.|last2=Ruta|first2=Marcello|last3=Friedman|first3=Matt|title=Ever Since Owen: Changing Perspectives on the Early Evolution of Tetrapods|journal=Annual Review of Ecology, Evolution, and Systematics|volume=39|issue=1|year=2008|pages=571–592|issn=1543-592X|doi=10.1146/annurev.ecolsys.38.091206.095546|jstor=30245177}}</ref>
{{clade
|label1='''{{nowrap|Crown-group Tetrapoda}}'''
|1={{clade
  |grouplabel1=total group Lissamphibia
  |1={{clade
    |label1=[[Temnospondyli]]
    |1=<div style="border-top: 2px solid green; padding: 0.1em;">'''Crown group [[Lissamphibia]]'''[[File:The tailless batrachians of Europe (Page 194) (Pelobates fuscus).jpg|x40px]]</div>
    |barend1=green
  }}
  |2=|state2=none
  |grouplabel3=total group Amniota|grouplabelstyle3=vertical-align:middle;
  |3={{clade
    |1={{extinct}} [[Embolomeri]] [[File:Archeria BW (white background).jpg|x30px]]|barbegin1=darkred
    |2={{clade
      |1={{extinct}} [[Gephyrostegidae]] [[File:Gefyrostegus22DB.jpg|x40px]]|bar1=darkred
      |2={{clade
        |1={{extinct}} [[Seymouriamorpha]] [[File:Karpinskiosaurus1DB.jpg|x30px]]|bar1=darkred
        |2={{clade

          |1={{clade
            |1={{extinct}} [[Microsauria]] [[File:Hyloplesion.jpg|x30px]]|bar1=darkred
            |2={{clade
              |1={{extinct}} [[Lysorophia]] [[File:Lysorophus.jpg|x40px]]|bar1=darkred
              |2={{clade
                |1={{extinct}} [[Adelospondyli]]|bar1=darkred
                |2={{clade
                  |1={{extinct}} [[Aistopoda]]|bar1=darkred
                  |2={{extinct}} [[Nectridea]] [[File:Diplocaulus Underside (Updated).png|x30px]]|bar2=darkred
 }} }} }} }}
          |2={{clade
            |1={{extinct}} [[Diadectomorpha]] [[File:Diadectes1DB (flipped).jpg|x25px]]|bar1=darkred
            |2='''Crown-group [[Amniota]]'''[[File:British reptiles, amphibians, and fresh-water fishes (1920) (Lacerta agilis).jpg|x30px]]|barend2=darkred
          }}
 }} }} }} }} }} }}

====Lepospondyl hypothesis (LH) ====
[[Cladogram]] modified after Laurin, ''How Vertebrates Left the Water'' (2010).<ref>{{harvnb|Laurin|2010|pp=133}}</ref>

{{clade| style=width:auto;font-size:90%;line-height:100%
|grouplabel1={{clade labels  |label1={{extinct}} stem tetrapods |top1=18%
                             |label2=total group Lissamphibia |top2=61%
                             |label3=total group Amniota |top3=92%}}
|label1='''Stegocephalia'''
|sublabel1=("Tetrapoda")
|1={{clade
   |1={{clade|1={{clade|1= {{extinct}} ''[[Acanthostega]]'' [[File:Acanthostega BW (flipped).jpg|70 px]] }} }} |barbegin1=green
   |2={{clade|1={{clade|1= {{extinct}} ''[[Ichthyostega]]'' [[File:Ichthyostega BW (flipped).jpg|70 px]] }} }} |bar2=green
   |3={{clade
      |1={{clade|1={{extinct}} [[Temnospondyli]] [[File:Eryops1DB.jpg|70 px]] }} |bar1=green
      |2={{clade
         |1={{extinct}} [[Embolomeri]] [[File:Archeria BW (white background).jpg|70 px]]|bar1=green
         |2={{clade
            |1={{extinct}} [[Seymouriamorpha]] [[File:Karpinskiosaurus1DB.jpg|70 px]]|barend1=green
            |2=|state2=none
            |3={{clade
               |label1=[[Amphibia]]
               |1={{clade
                  |1={{clade
                     |1={{extinct}} [[Adelogyrinidae]] |barbegin1=midnightblue
                     |2={{extinct}} [[Aistopoda]] |bar2=midnightblue
                     }}
                  |2={{clade
                     |1={{clade|1= {{extinct}} [[Nectridea]] [[File:Diplocaulus Underside (Updated).png|70 px]] }} |bar1=midnightblue
                     |2={{clade
                        |1={{extinct}} [[Lysorophia]] [[File:Lysorophus.jpg|70 px]]|bar1=midnightblue
                        |2={{clade
                           |1='''[[Lissamphibia]]''' [[File:The tailless batrachians of Europe (Page 194) (Pelobates fuscus).jpg|50 px]]   |barend1=midnightblue
                           }} 
                        }} 
                     }} 
                  }} 
               |2=|state2=none
               |label3=[[Reptiliomorpha]]
               |3={{clade
                  |1={{extinct}} [[Diadectomorpha]] [[File:Diadectes1DB (flipped).jpg|70 px]] |barbegin1=darkred
                  |2='''[[Amniota]]'''  [[File:British reptiles, amphibians, and fresh-water fishes (1920) (Lacerta agilis).jpg|70 px]] |barend2=darkred
                  }}
               }} 
            }} 
         }} 
      }} 
   }} 
}}

==== Polyphyly hypothesis (PH) ====
This hypothesis has batrachians (frogs and salamanders) coming out of dissorophoid temnospondyls, with caecilians out of microsaur lepospondyls. There are two variants, one developed by [[Robert L. Carroll|Carroll]],<ref name="Carroll2007">{{cite journal |last1=Carroll |first1=Robert L. |title=The Palaeozoic Ancestry of Salamanders, Frogs and Caecilians |journal=Zoological Journal of the Linnean Society |volume=150 |issue=s1 |year=2007 |pages=1–140 |issn=0024-4082 |doi=10.1111/j.1096-3642.2007.00246.x |doi-access=free}}</ref> the other by Anderson.<ref name="Anderson2008">{{cite journal |last1=Anderson |first1=Jason S. |title=Focal Review: The Origin(s) of Modern Amphibians |journal=Evolutionary Biology |volume=35 |issue=4 |date=December 2008 |pages=231–247 |issn=0071-3260 |doi=10.1007/s11692-008-9044-5 |bibcode=2008EvBio..35..231A |s2cid=44050103}}</ref>

[[Cladogram]] modified after Schoch, Frobisch, (2009).<ref name="FrobischSchoch2009">{{cite journal |last1=Frobisch |first1=N. B. |last2=Schoch |first2=R.R. |title=Testing the Impact of Miniaturization on Phylogeny: Paleozoic Dissorophoid Amphibians |journal=Systematic Biology |volume=58 |issue=3 |year=2009 |pages=312–327 |issn=1063-5157 |doi=10.1093/sysbio/syp029 |pmid=20525586 |doi-access=free}}</ref>
{{clade| style=width:auto;font-size:100%;line-height:100%
|label1='''Tetrapoda'''
|1={{clade
  |1=stem tetrapods  |state1=double
  |2={{clade
  |1={{clade
    |label1=[[Temnospondyli]]
    |1={{clade
      |1=basal temnospondyls |state1=double
      |label2=[[Dissorophoidea]]
      |2={{clade
        |1={{clade
          |1={{extinct}} [[Amphibamidae]]
          |2='''[[Frog]]s''' [[File:The tailless batrachians of Europe (Page 194) (Pelobates fuscus).jpg|45 px]]
}}
      |2={{clade
          |1={{extinct}} [[Branchiosauridae]] [[File:Branchiosaurus_BW.jpg|70 px]]
          |2='''[[Salamander]]s''' [[File:Salamandra salamandra (white background).jpg|70 px]]
}} }} }}
      |2={{clade
      |label1=[[Lepospondyli]]
      |1={{clade
            |1={{extinct}} [[Lysorophia]] [[File:Lysorophus.jpg|70 px]]
      |2={{clade
          |1={{extinct}} [[Microsauria]] [[File:Hyloplesion.jpg|70 px]]
          |2='''[[Caecilians]]''' [[File:Syphonops annulatus cropped.jpg|70 px]]
}} }} }} }}
      |2={{clade
        |1={{clade
          |1={{extinct}} [[Seymouriamorpha]] [[File:Karpinskiosaurus1DB.jpg|70 px]]
          |2={{clade
              |1={{extinct}} [[Diadectomorpha]] [[File:Diadectes1DB (flipped).jpg|70 px]]
              |2='''[[Amniota]]''' [[File:British reptiles, amphibians, and fresh-water fishes (1920) (Lacerta agilis).jpg|70 px]]
}} }} }} }} }} }}