Agnostida                                                                                Online

  Ptychagnostus cuyanus (I)                                                            (-)

         Marjum Formation, Middle Cambrian (ca. 525Mio. Years)

  Ptychopariida                                                                          

  Brachyaspidion sulcatum (I)                                                         (+)

         Wheeler Formation, Lower Cambrian (ca. 540Mio. Years)

  Elrathia kingii (I) (II)                                                                   (+) (+)

         Wheeler Formation, Lower Cambrian (ca. 540Mio. Years)