The Ashizawa Formation is a Coniacian geologic formation in northeastern Honshu, Japan. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607. A jawbone belonging to a therian mammal has also been discovered from this unit.Kusuhashi, N., Suzuki, T., Terui, K., Sato, A., and Amiot, R. (2016) A Late Cretaceous mammalian dentary from the Ashizawa Formation (Futaba Group), Fukushima, northeastern Japan. Island Arc, 25: 403–409. doi: 10.1111/iar.12133.
Fossil content The following fossils were reported from the formation:
Dinosaurs
Ornithischians Ornithischians of the Ashizawa FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Hadrosauroidea Indet. Indeterminate Fukushima Prefecture, Honshu, Japan Coniacian A hadrosauroid ornithopod] Styracosterna indet. Indeterminate Fukushima Prefecture, Honshu, Japan Coniacian A styracosternan iguanodonian
Theropods Theropos of the Ashizawa FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Theropoda indet. Indeterminate Fukushima Perfecture, Honshu, Japan Coniacian Tibia An indeterminate theropod; informally known as "Futabasaurus".
Mammals Mammals of the Ashizawa FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Theria indet. Indeterminate Fukushima Perfecure, Honshu, Japan Coniacian An indeteminate therian.
Fish Fishes of the Ashizawa FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Squalus S. sp. Fukushima Perfecture, Honshu, Japan Coniacian An spurdog
Mollusks
Bivalves Bivalves of the Ashizawa FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Inoceramus I. uwajimensis Fukushima Prefecture, Honshu, Japan Coniacian A inoceramid bivalve
Cephalopods Cephalopods of the Ashizawa FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImage Anagaudryceras A. limatum Fukushima Prefecture, Honshu, Japan Coniacian A gaudryceratid lytoceratine Eubostrychoceras E. indopacificum Fukushima Prefecture, Honshu, Japan Coniacian A nostoceratid turrilitoid Forresteria F. alluaudi Fukushima Prefecture, Honshu, Japan Coniacian A barroisiceratine collignoniceratid Gaudryceras G. denseplicatum Fukushima Prefecture, Honshu, Japan Coniacian A gaudryceratid lytoceratine Pseudoxybeloceras P. sp. Fukushima Prefecture, Honshu, Japan Coniacian A diplomoceratid ammonite Tongoboryceras T. kawashitai Fukushima Prefecture, Honshu, Japan Coniacian A pachydiscid desmoceratoid Yabeiceras Y. orientale Fukushima Prefecture, Honshu, Japan Coniacian A barroisiceratine collignoniceratid Yezoceras Y. elegans Fukushima Prefecture, Honshu, Japan Coniacian A nostoceratid turrilitoid Y. miotuberculatum Yezoites Y. pseudoaequalis Fukushima Prefecture, Honshu, Japan Coniacian A otoscaphitine scaphitid
See also
List of dinosaur-bearing rock formations List of stratigraphic units with indeterminate dinosaur fossils
Footnotes
References Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. .