Abstract
The trace fossils from the Middle Devonian Tiaomajian Formation in Xinhua and Xiangtan, Hunan were previously described and published(Zhang Xinping, 1991). They are referred to 15 ichnogenera and 21 ichnospecies, namely, Arenicolites hunauensis, Cochlichnus xinhuaensis, Cochlichnus luguanensis, Cochlichnus ichnosp., Chondrites Type B Osgood, Chondrites Type C Osgood, Gordia marina, Tinoichnus lineata, Monocraterion ichnosp., Phycodes pedum, Phycoles of. Phycodes of. pedun, Phycodes of. pal, palaeophycus tabularis, Palaeophycus? cf. Curoatus, Planolites lererleyensis, Palaeiphycus montanus, Rouaultia ichnosp., Rhizocorallimn tongtianexsis, Rhizocralsimn ichnosp., Skoluhos linearis, Thallassinoides, Zoophycus aff. crassus, Zoophycus ichnosp.
They are mainly included in Arenicolides—Palaeophycus assemblage, Slolithos—Planolites assemblage, Palaeophycus—Gordia assemblage and Rhizocorallium—Planolites assemblage, all being located in the upper part of the Tiaomajian Formation, representing nearshore environments and belonging to Cruziam ichnofacies. Part of them may be included in Zoophycus—Skoluhos assemblage and Zoophycus —Cochlichnus assemblage belonging to Zoophycus ichnofacies, occurring in the uppermost part of the Tiaomajian Formation and representing offshore environments.
The author contends in this paper that there are 22 ichnogenera and 40 ichnospecies altogether recognized in the Tiaomajian Formation. They may be divided into 8 ethological and ecological types, namely Domuchuia, Fodinichnia, Repichnia, Cabichnia, Pasichuia, borings, escape traces and bioturbation structures. from bottom to top of the Tiaomajian Formation, the ichnoassemblage of Domuchuia is replaced by Domuchuia in combination with Fodichnia or Fodichnia, and Pascichnia accordingly, representing the sedimentary environments ranging from foreshore to nearshore, then to offshore, whereas the sea water deepens and becomes broader and broader.
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