Paleontological Research, vol. 9, no. 2, pp. 203–213, June 30, 2005 6 by the Palaeontological Society of Japan Charophyte gyrogonites from the Lower Cretaceous KitadaniFormationoftheTetoriGroupinthe Takinamigawa area, Katsuyama City, Fukui Prefecture, central Japan KATSUHIRO KUBOTA Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, 305-8572, Japan (e-mail:
[email protected]) Received December 22, 2004; Revised manuscript accepted April 21, 2005 Abstract. Well preserved charophyte gyrogonites are discovered from the Kitadani Formation of the Te- tori Group in the Takinamigawa area, Katsuyama City, Fukui Prefecture, central Japan. The Kitadani charoflora described in this paper is composed of five species of three genera, Clavator harrisii var. reyi (Grambast-Fessard), Mesochara harrisi (Ma¨dler), Mesochara stipitata (Wang), Mesochara sp., and Stel- latochara sp. C. harrisii var. reyi is a member of Clavatoraceae, which is a biostratigraphically well estab- lished charophyte group and is unique in Upper Jurassic to Cretaceous nonmarine deposits. The occur- rences of C. harrisii var. reyi associated with other charophytes indicate that the charophyte-rich horizon of the Kitadani Formation is assigned to the Barremian, which well agrees with the age estimation established by the nonmarine molluscan assemblage. Key words: charophyta, Early Cretaceous, Fukui Prefecture, Kitadani Formation, Takinamigawa area, Tetori Group Introduction to fresh water. The body consists of a stem and fructifications. Since the fructification is calcified or Biostratigraphic correlation among Cretaceous preserved as an impression and has a rapid evo- nonmarine deposits in Japan has been studied by lutionary rate, it is suitable for an index fossil in non- many workers, who are dependent mainly on non- marine deposits (Martin-Closas, 1996).