The standard biostratigraphy of Carboniferous and Permian are constructed on the basis of
  fusulinaceans in Thailand (Toriyama et al., 1975; Ingavat, 1984).  The Carboniferous and Permian
  ammonoids have been recently reported from Thailand (Glenister et al, 1990; Ishibashi and
  Chonglakmani, 1990; Ishibashi et al, 1994, 1996).  Of those Permian ammonoids are rich in the Lower
  and Upper Permian.  The Carboniferous ammonoids including the questionable species are only recorded
  from north and south Thailand.  Those ammonoids coexist occasionally with fusulinids, srnaller
  foraminifers, bryozoans, brachiopods and so on.
         The Carboniferous ammonoids are abundantly recognized at northern part of Loei by the
  occurrence of Branneroceras fauna of Namurian, upper Lower Carboniferous. It includes some species of
  Syngastrioceras sp., Neogastrioceras sp., Bisatoceras sp. and several species of nautiloids including
  orthoceratids.  Recently Protocanites sp. and Pronorites sp.  Of the Lower Carboniferous are found in the
  nothwestem area (Ingavat Helrncke, 1994).
          The Permian ammonoids consist of Properrinites boesei - Artinskia loeiensis at Sakmarian, Lower
  Permian, Propinacoceras sp. at Yahtashian-Bolorian, Lower Middle Permian, Agathiceras aff. suessi at
  Bolorian, lower Middle Permian, Paratirolltes nakornsrii-Tapashanites yaowalakae at Dorashamian,
  Upper Permian.      The upper Middle to lower Lower Perrnian ammonoid zones correlated with
  Neoschwagerina craticulifera to Lepidolina multiseptata zones have not been yet reported from Thailand.