scholarly journals Organic geochemical studies on mudrocks from the Upper Cretaceous Himenoura Groupwith oil seepage in Himedo Town, Kami-Amakusa City, Kumamoto Prefecture, southwest Japan

2020 ◽  
Vol 78 (2) ◽  
pp. 77-89
Author(s):  
Ryuta Kiyono ◽  
Hiroki Matsuda ◽  
Shoki Kurokawa ◽  
Hideki Nishita ◽  
Masahiko Yagi
Keyword(s):  
Upper Cretaceous ◽  
Southwest Japan ◽  
Oil Seepage ◽  
Geochemical Studies

scholarly journals Mosasaur remains from the Upper Cretaceous Izumi Group of southwest Japan

2005 ◽  
Vol 84 (3) ◽  
pp. 373-378 ◽  
Author(s):  
M. Tanimoto
Keyword(s):  
Upper Cretaceous ◽  
Similar Type ◽  
Southwest Japan ◽  
Osaka Prefecture ◽  
Upper Campanian

AbstractUntil recently, mosasaur remains from the Izumi Group (Upper Cretaceous) in southwest Japan comprised only scattered finds; now a richer material is available. From the upper Campanian Hiketa Formation in Kagawa Prefecture, Kourisodon sp. has just been recorded, on the basis of portions of skull and mandible which has small and laterally compressed teeth. A few teeth of the same or similar type have previously been described from the Maastrichtian Mutsuo Formation in Osaka Prefecture. A report of Mosasaurus sp. A, which resembles M. missouriensis and M. dekayi, is based on some cranial and mandible remains, inclusive of numerous teeth and a few well-preserved cervical and two incomplete dorsal vertebrae, from the Maastrichtian Mutsuo Formation in Osaka Prefecture. A slender tooth of Mosasaurus sp. from the Mutsuo Formation has since been reassigned to Platecarpus (Plioplatecarpinae); yet, this may indeed by a species of Mosasaurus, here listed as Mosasaurus sp. B. To date, smaller specimens of mosasaurids have been shown to be abundant in the Izumi Group, which suggests two possible explanations. Either most of these represent juveniles, or smaller-sized, Kourisodon-like animals flourished here. Finds of Kourisodon sp. from the upper Campanian Hiketa Formation and the Maastrichtian Mutsuo Formation suggests the second explanation is the more likely one.

Late Cretaceous gastropods from the Izumi Group of southwest Japan

1990 ◽  
Vol 64 (4) ◽  
pp. 563-578 ◽  
Author(s):  
Tomoki Kase
Keyword(s):  
Late Cretaceous ◽  
North American ◽  
Upper Cretaceous ◽  
Coastal Areas ◽  
Basal Part ◽  
Northwestern Pacific ◽  
New Genera ◽  
Southwest Japan ◽  
The North ◽  
The Family

The basal part of the Upper Cretaceous, mid-Campanian to Maastrichtian Izumi Group of the Izumi Mountains and Awaji Island, Southwest Japan, contains the most diverse gastropod fauna of this age in Japan. This paper discriminates 19 species and describes two new genera: Atira tricarinata n. sp., Ataphrus (s.s.) sp. A, Ataphrus (s.s.) sp. B, Globularia (s.s.) izumiensis n. sp., Lysis izumiensis n. sp., Trichotropis? sp., Deussenia takinoikensis n. sp., Volutilithes antiqua n. sp., Pseudoperissitys bicarinata Nagao and Otatume, Nekewis sp., Nipponitys inouei n. gen. and sp., Nipponitys acutangularis n. gen. and sp., Nipponitys sp. cf. N. magna (Kalishevitsch), Calorebama cretacea n. sp., Taniella japonica n. gen. and sp., Amuletum (s.s.) sp., Biplica osakensis n. sp., Biplica sphaerica n. sp., and Cylichna sp. The family Ampullospiridae is assigned to the suborder Architaenioglossa from the superfamily Naticacea. The enigmatic genus Lysis is tentatively assigned to the Calyptraeidae. Taniella japonica n. sp. is the oldest member of the family Olividae, and Calorebama cretacea n. sp. is the oldest member of the subfamily Pseudolivinae. Occurrence of Atira, Ataphrus, Biplica, and five perissityids further supports close communication of the northwestern Pacific Late Cretaceous gastropod faunas with those of the North American Pacific coastal areas.

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