Editing Vertebrate (section)

=== Internal phylogeny ===

The internal phylogeny of the vertebrates is shown in the below tree.<ref name="UCMP 2024">{{cite web |title=Adding time to the tree |website=Understanding Evolution |publisher=University of California Museum of Paleontology |url=https://evolution.berkeley.edu/evolution-101/the-history-of-life-looking-at-the-patterns/adding-time-to-the-tree/ |access-date=8 December 2024}}</ref>

{{clade|style=font-size:85%;line-height:85%;                           
|label1='''Vertebrata''' |sublabel1=(backbone)
|1={{clade 
   |sublabel1=(jawless) 
   |1=[[Agnatha]]{{efn|Agnatha as traditionally defined is paraphyletic, that is, a taxon including all jawless fishes, but if one only includes living species then the group becomes monophyletic.}} [[File:Nejonöga, Iduns kokbok.jpg|90 px]]
   |label2=[[Gnathostomata]]
   |sublabel2=(jawed)
   |2={{clade
      |label1=[[Chondrichthyes]] |sublabel1=(cartilaginous)
      |1=<span style="{{MirrorH}}">[[File:White shark (Duane Raver).png|75 px]]</span>
      |label2=[[Osteichthyes]] |sublabel2=(bony fishes)
      |2={{clade
         |1={{clade
            |label1=[[Actinopterygii]] |sublabel1=(ray-fins)
            |1=[[File:Common carp (white background).jpg|70px]]
            |label2=[[Sarcopterygii]] |sublabel2=(lobe-fins)
            |2={{clade
               <!--|label1=[[Actinistia]]-->
               |1=[[Coelacanth]]s [[File:Coelacanth flipped.png|70 px]]
               |label2=[[Rhipidistia]] |sublabel2=(lungs)
               |2={{clade
                  |1=[[Lungfish]]es [[File:Barramunda coloured.jpg|75 px]]
                  |label2=[[Tetrapod]]a |sublabel2=(4 limbs)
                  |2={{clade
                     |1=[[Amphibian]]s [[File:Salamandra_salamandra_(white_background).jpg|80 px]] 
                     |label2=[[Amniote|Amniota]] |sublabel2=(amnion)
                     |2={{clade
                        |1=[[Mammal]]s [[File:Rattus norvegicus (white background).png|55px]]
                        |label2=[[Sauropsida]] |sublabel2=(scaly skin)
                        |2={{clade
                           |1=[[Lepidosauria|Lepidosaurs]] [[File:Python natalensis Smith 1840 white background.jpg|70px]] 
                           |2={{clade
                              |1=[[Turtle]]s [[File:Erpétologie générale, ou, Histoire naturelle complète des reptiles (Morenia ocellata).jpg|55px]]
                              |2={{clade
                                 |1=[[Crocodilia|Crocodilians]] [[File:Bristol.zoo.westafrican.dwarf.croc.arp. white background.jpg|70px]] 
                                 |2=[[Dinosaur]]s [[File:Spot-billed pelican takeoff white background.jpg|60px]]
                                 }}
                              }}
                           }}
                        }}
                     }} 
                  }}
               }}
            }}
         }}
      }}
   }}
}}

The placement of hagfishes within the vertebrates has been controversial. Their lack of proper vertebrae (among other characteristics of jawless lampreys and jawed vertebrates) led authors of phylogenetic analyses based on [[morphology (biology)|morphology]] to place them outside Vertebrata.<ref>{{Cite journal |last1=Ota |first1=Kinya G. |last2=Fujimoto |first2=Satoko |last3=Oisi |first3=Yasuhiro |last4=Kuratani |first4=Shigeru |date=2017-01-25 |title=Identification of vertebra-like elements and their possible differentiation from sclerotomes in the hagfish |journal=Nature Communications |volume=2 |pages=373 |doi=10.1038/ncomms1355|pmc=3157150 |pmid=21712821 |bibcode=2011NatCo...2..373O}}</ref> [[Molecular data]] however indicates that they are vertebrates, being most closely related to lampreys.<ref name=hagfish>{{cite journal |title=Monophyly of Lampreys and Hagfishes Supported by Nuclear DNA–Coded Genes |last1=Kuraku |date=December 1999 |journal=[[Journal of Molecular Evolution]] |volume=49 |pages=729–35 |doi=10.1007/PL00006595 |pmid=10594174 |last2=Hoshiyama |first2=D. |last3=Katoh |first3=K. |last4=Suga |first4=H. |last5=Miyata |first5=T. |issue=6 |bibcode=1999JMolE..49..729K |s2cid=5613153 }}</ref><ref>{{cite journal |last1=Stock |first1=D. |last2=Whitt |first2=G. S. |title=Evidence from 18S ribosomal RNA sequences that lampreys and hagfish form a natural group |journal=[[Science (journal)|Science]] |date=7 August 1992 |volume=257 |issue=5071 |doi=10.1126/science.1496398 |pages=787–789 |pmid=1496398 |bibcode=1992Sci...257..787S }}</ref> An older view is that they are a sister group of vertebrates in the common taxon of Craniata.<ref>{{cite journal |last=Nicholls |first=H. |title=Mouth to Mouth |date=10 September 2009 |journal=[[Nature (journal)|Nature]] |volume=461 |issue=7261 |pages=164–166 |doi=10.1038/461164a |pmid=19741680 |doi-access=free}}</ref> In 2019, Tetsuto Miyashita and colleagues reconciled the two types of analysis, supporting the [[Cyclostomata]] hypothesis using only morphological data.<ref>{{Cite journal |last1=Miyashita |first1=Tetsuto |last2=Coates |first2=Michael I. |last3=Farrar |first3=Robert |last4=Larson |first4=Peter |last5=Manning |first5=Phillip L.|last6=Wogelius |first6=Roy A.|last7=Edwards |first7=Nicholas P.|last8=Anné |first8=Jennifer |last9=Bergmann |first9=Uwe |last10=Palmer |first10=A. Richard |last11=Currie |first11=Philip J. |display-authors=5 |date=2019-02-05 |title=Hagfish from the Cretaceous Tethys Sea and a reconciliation of the morphological–molecular conflict in early vertebrate phylogeny |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=116 |issue=6 |pages=2146–2151 |doi=10.1073/pnas.1814794116 |pmc=6369785 |pmid=30670644 |bibcode=2019PNAS..116.2146M |doi-access=free}}</ref>

{{clade|style=font-size:85%;line-height:85%;
|1={{clade
   |1=†[[Myllokunmingiidae|Myllokunmingiida]]<span style="{{MirrorH}}">[[File:Myllokunmingia.png|55px]]</span>
   |label2= '''Vertebrata''' |sublabel2=(crown group)
   |2={{clade
      |1={{clade
         |1=†[[Anaspida]] [[File:Anaspida.png|50 px]]
         |2={{clade
            |1=†''[[Pipiscius]]''
            |2={{clade
               |1=†[[Conodont]]a<span style="{{MirrorH}}">[[File:ConodontZICA.png|90px]]</span>
               |2=[[Cyclostomata]] (lampreys and hagfishes) [[File:Nejonöga, Iduns kokbok.jpg|90 px]] 
               }} 
            }}
         }}
      |2=[[Gnathostomata]] (jawed vertebrates)<span style="{{MirrorH}}"><span style="{{MirrorH}}"> [[File:Dunkleosteus terrelli 2024 reconstruction.jpg|70 px]]</span></span>
      }}
   }}
}}