After Carroll, 1988

<==o †Trimerorhachoidea
   |--o †Trimerorhachidae
   |  |?- †Doragnathus woodi Smithson, 1980
   |  |-- †Lafonius
   |  |-- †Nannospondylus
   |  |-- †Neldasaurus
   |  |-- †Slaughenhopia
   |  `-- †Trimerorhachis
   `--o †Saurerpetontidae
      |-- †Saurerpeton
      |-- †Acroplous vorax Hotton, 1959
      |-- †Erpetosaurus
      `-- †Isodectes

Reference(s):