Ocadia nipponica, a new species of aquatic turtle (Testudines: Testudinoidea: Geoemydidae) from the Middle Pleistocene of Chiba Prefecture, central Japan

Ren Hirayama, Naotomo Kaneko, Hiroko Okazaki

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A new species of the genus Ocadia (Testudines; Testudinoidea; Geoemydidae), O. nipponica, is described on the basis of a nearly complete skeleton from the Middle Pleistocene Kiyokawa Formation of the Shimosa Group at Sodegaura City, Chiba Prefecture, central Japan. O. nipponica is distinguished from O. sinensis (Gray) by its more extensive secondary palate, smoother shell surface, narrower second and third vertebral scutes, and larger size (carapace up to 33 cm long). Considering that the living species O. sinensis is distributed in the coastal area of eastern to southeastern Asia in subtropical to tropical climates, the new fossil species may have been thrived in warmer paleoclimatic conditions for the Japanese Islands in the Pleistocene age than hitherto have been estimated on the basis of floral evidences.

Original languageEnglish
Pages (from-to)1-19
Number of pages19
JournalPaleontological Research
Issue number1
Publication statusPublished - 2007 Apr 30



  • Chiba Prefecture
  • Kiyokawa Formation
  • Ocadia nipponica sp. nov.
  • Paleoclimate
  • Pleistocene
  • Reptilia

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Palaeontology

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