After Carroll, 1988, and Janvier, 1997

<==o †Pteraspidomorphi Goodrich, 1909
   |-- †Anatolepis heintzi Bockelie & Fortey, 1976
   `--+--o †Arandaspida Ritchie & Gilbert-Tomlinson, 1977
      |  |?- †Pircanchaspis rinconensis Erdtmann et al., 2000
      |  |--o †Sacabambaspis Gagnier, Blieck & Rodrico, 1986 [Sacabambaspidae] Ord. Aust. SWAs., ESAm.
      |  |  |-- †S. sp. [Young, 1997] [Ordovician, Central Australia]
      |  |  |-- †S. sp. [Sansom et al, 2009] [Ordovician, Arabian Peninsula, Oman]
      |  |  |-- †S. sp. [Albanesi & Astini, 2002] [Ordovician, Argentina]
      |  |  `-- †S. janvieri Gagnier, Blieck & Rodrico, 1986; Ord. ESAm.
      |  `--o †Arandaspididae Ritchie & Gilbert-Tomlinson, 1977
      |     |--o †Arandaspis Ritchie & Gilbert-Tomlinson, 1977
      |     |  |-- †A. sp. [Young, 1997] [Ordovician, Central Australia]
      |     |  `-- †A. prionotolepis Ritchie & Gilbert-Tomlinson, 1977
      |     `--o †Porophoraspis Ritchie & Gilbert-Tomlinson, 1977
      |        |-- †P. sp. [Young, 1997] [Ordovician, Central Australia]
      |        `-- †P. crenulata Ritchie & Gilbert-Tomlinson, 1977
      `--o †Heterostracomorphi Lankester, 1868 [Heterostraci Lankester, 1868]
         |-- †Astraspis desiderata Walcott, 1892 [taxonomic history] [Astraspida Berg, 1940: Astraspidiformes Berg, 1940: Astraspidae Eastman, 1917]
         `--+--o †Eriptychiida Ørvig, 1958
            |  |-- †Eriptychius americanus Walcott, 1892 [taxonomic history] [Eriptychiidae Tarlo, 1962]
            |  `--o †Oniscolepidae Märss & Karatajute-Talimaa, 2009
            |     |-- †Oniscolepis dentata Pander, 1856 [taxonomic history]
            |     `-- †Kallostrakon podara Lankester
            `--o †Heterostraci Lankester, 1868
               |?- †Aserotaspis canadensis Dineley & Loeffler, 1976
               |?- †Lepidaspis serrata Dineley & Loeffler, 1976
               |?- †Natlaspis planicosta Dineley & Loeffler 1976
               |?-o †Tesseraspis Wills [Tesseraspidiformes: Tesseraspididae Berg]
               |  |-- †T. tessellata Wills
               |  `-- †T. mosaica
               `--+--o †Traquairaspidiformes
                  |  `--o †Traquairaspididae
                  |     |--o †Phialaspis Wills, 1935 [?Traquairaspis; Lophopiscis; Lophaspis; Orthaspis; Yukonaspis]
                  |     |  `-- †P. symondsi [Traquairaspis symondsi]
                  |     |--o †Traquairaspis
                  |     |  `-- †T. pococki
                  |     `--o †Weigeltaspis
                  |        |-- †W. godmani Tarlo
                  |        `-- †W. brotzeni Tarlo, 1964
                  `--+--o †Tolypelepidida Denison, 1964 [Cyathaspididae: Tolypelepidinae Denison, 1964]
                     |  `--o †Tolypelepididae Denison, 1964 [Tolypelepidinae Denison, 1964]
                     |     |-- †Asketaspis interstincta Dineley & Loeffler, 1976
                     |     |-- †Athenaegis chattertoni Soehn & Wilson, 1990
                     |     `--o †Tolypelepis Pander, 1856 [Tolypaspis]
                     |        |-- †T. undulata Pander, 1856 [Oniscolepis magnus]
                     |        |-- †T. lenzi Dineley & Loeffler, 1976
                     |        `-- †T. leopoldensis Loeffler & Jones, 1977
                     `--+-- †Cynthaspidiformes
                        `-- †Pteraspidiformes Berg, 1940

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