上部三畳系成羽層群における 日本最古の化石林の発見 ―堆積環境復元および古植生復元における意義―

Erect fossil stumps were found from the outcrop of the Upper Triassic Hinabata Formation, the uppermost part of the Nariwa Group at Hinabata, Nariwa-cho,Takahashi City, Okayama Prefecture, SW Japan. They are evidence of the oldest fossil forest in Japan. The Upper Triassic Nariwa Group is mostly composed of non-marine deposits except the marine Jito Formation and characterized by the abundance in plant fossils. The marine Jito Formation is characterized by occurrence of Norian Monotis ochotica. On the basis of detailed observation of the occurrence of erect fossil stumps, as well as sedimentary facies of fossil-bearing unit, the fossil forest was interpreted to have grown on the top of the natural-levee units. One of the erect fossil stumps was identified as Xenoxylon sp.