Editing Placoderm (section)

==Cladogram==
{{See also|Agnatha#Groups}}
The following [[cladogram]] shows the interrelationships of placoderms according to Carr ''et al.'' (2009):<ref name=CJR09>{{cite journal |last1=Carr |first1=Robert K. |last2=Johanson |first2=Zerina |last3=Ritchie |first3=Alex |title=The phyllolepid placoderm ''Cowralepis mclachlani'': Insights into the evolution of feeding mechanisms in jawed vertebrates |journal=Journal of Morphology |date=July 2009 |volume=270 |issue=7 |pages=775–804 |doi=10.1002/jmor.10719 |pmid=19215000 |s2cid=45258255 }}</ref>

[[File:Homostius2DB.jpg|thumb|right|''[[Homostius]]'' and ''[[Pterichthys]]'']]
[[File:Diandongpetalichthys baojiaoshanensis.jpg|thumbnail|''[[Diandongpetalichthys]]'']]
{{clade| style=font-size:100%;line-height:85%
|1={{clade
   |1=''[[Stensioella]]''
   |label2='''Placodermi'''
   |2={{clade
      |1=''[[Pseudopetalichthys]]''
      |2={{clade
         |1=''[[Brindabellaspis]]''
         |2=[[Acanthothoraci]]}}
      |3={{clade
         |1=[[Rhenanida]]
         |2={{clade
            |1={{clade
               |1=''[[Yunnanolepis]]''
               |2=[[Euantiarcha]]}}
            |2={{clade
               |1={{clade
                  |1=[[Petalichthyida]]
                  |2=[[Ptyctodontida]]}}
               |label2=[[Arthrodira]]
               |2={{clade
                  |1=''[[Wuttagoonaspis]]''
                  |2=[[Actinolepidae]]
                  |3={{clade
                     |1=[[Phyllolepida]]
                     |2={{clade
                        |1=[[Phlyctaeniida]]
                        |label2=[[Brachythoraci]]
                        |2={{clade
                           |1={{clade
                              |1=''[[Holonema]]''
                              |2=''[[Antineosteus]]''
                              |3=[[Buchanosteidae]]}}
                           |label2=[[Eubrachythoraci]]
                           |2={{clade
                              |1={{clade
                                 |1={{clade
                                    |1=''[[Pholidosteus]]''
                                    |2=''[[Tapinosteus]]''}}
                                 |2={{clade
                                    |1=''[[Coccosteus]]''
                                    |2=''[[Torosteus]]''}} }}
                              |2=''[[Plourdosteus]]''
                              |3={{clade
                                 |1=''[[Dunkleosteus]]''
                                 |2={{clade
                                    |1=''[[Brachyosteus]]''
                                    |2=''[[Erromenosteus]]''
                                    |3=''[[Gorgonichthys]]''
                                    |4=''[[Titanichthys]]''
}} }} }} }} }} }} }} }} }} }} }} }} }}

However, the cladogram had changed significantly over the years, and the placoderms are now thought to be [[paraphyletic]],<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> with some being more closer to the [[Eugnathostomata]] than others. The updated cladogram (Zhu et al., 2016):<ref name=zhu2016>{{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>
{{Clade|style=font-size:85%;line-height:85%
|1={{Clade
  |state1=double
   |1=[[Cephalaspidomorphi]]
   |label2=[[Gnathostomata]]
   |2={{Clade
      |1=[[Antiarchi]]
      |2={{Clade
         |1=[[Petalichthyida]]
         |2={{Clade
            |1={{Clade
               |1=[[Arthrodira]]
               |2=[[Ptyctodontida]]}}
            |2={{Clade
               |1=''[[Qilinyu]]''
               |2={{Clade
                  |1=''[[Entelognathus]]''
                  |2={{Clade
                     |1=''[[Janusiscus]]''
                     |2={{Clade
                        |label1=[[Eugnathostomata]]
                        |1={{Clade
                           |1=[[Chondrichthyes]] (total group, including [[Acanthodii]] as stem lineages)
                           |2=[[Osteichthyes]]
}} }} }} }} }} }} }} }} }} }}