T.Ishibashi, M.Fujikawa, S.Yoda & Nikorn Nakornsri:

     The Dorashamian faunas of the Huai Thak Formation in North Thailand is composed by
 many taxa such as ammonoids, nautiloids, bivalves, gastropods, trilobites, brachiopods, rugose
 corals, bryozoans, foraminifers including fusulines, sponges, algae, etc., of which fusulines
 and ammonoids are useful for biostratigraphy of the calcarous and clastic sediments
 respectively.  Foramininifera faunas represent the Gallowayinella and Colaniella-Reichelina zones.
 The ammonoids, consisting of Paratirolites nakornsrii and Tapashanites yaowalakae, occur in
 the uppermost horizon of the Doi Pha Phlung area.  A barren zone of partly dolomitised
 limestone occurs at the top of 557 m at the Doi Pha Phlung and overlies the Colaniella
 parva Zone. It is interpreted that the stratigraphical horizon of the barren limestone is higher
 than that of the latter.  The clastic rocks composed of shale, sandstone and conglomerate are
 in a fault contact to the shale of the Lower Triassic Phra That Formation.