The Kuwajima Formation is an Early Cretaceous geologic formation in Japan. Its precise age is uncertain due to a lack of identifying fossils, and it was previously considered likely Valanginian to Hauterivian in age. However, it is now considered to probably be Barremian in age. Dinosaurs and other vertebrates has been recovered from the Kaseki-kabe "Fossil-bluff" locality in the uppermost part of the formation.

The multituberculate mammals Hakusanobaatar matsuoi and Tedoribaatar reini are known from the Kuwajima Formation. A member of Tritylodontidae, Montirictus kuwajimaensis, has also been recovered from the unit.Hiroshige Matsuoka, Nao Kusuhashi and Ian J. Corfe (2016). "A new Early Cretaceous tritylodontid (Synapsida, Cynodontia, Mammaliamorpha) from the Kuwajima Formation (Tetori Group) of central Japan". Journal of Vertebrate Paleontology. Online edition:

Vertebrate Paleobiota After Matsuoka et al. (2002)

Fish Fish reported from the Kuwajima FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImagesSinamiaS. kukurihimeMostly complete skeletonAn amiiform fish related to bowfinsTetoriichthysT. kuwajimaensisThe oldest record of OsteoglossiformLepidotesL. sp.PachycormidaeIndeterminateJaw

Amphibians Amphibians reported from the Kuwajima FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImagesShirerpetonS. isajiiKaseki-kabe Facies IIIPartial disarticulated skullAlbanerpetontidAnuraIndeterminateIsolated longbone, as well as a partial skeleton "composed of a few skull elements and several postcranial bones, including the femur, ilium, and vertebrae"Partial skeleton belongs to a basal frog that lies outside of Neobatrachia.

Choristoderes Choristoderes reported from the Kuwajima FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImagesMonjurosuchusIndeterminateKaseki-kabe Facies IIINeochoristoderaIndeterminateFacies IThe first report of a neochoristodere from JapanChoristoderaIndeterminateKaseki-kabe Facies III

Squamates Squamates reported from the Kuwajima FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImagesAsagaolacertaA. tricuspidensKaseki-kabe Facies III"An association of skull, jaws and postcranial bones of a small lizard with facetted tricuspid teeth, possibly a right maxilla"HakusepsH. imberis Kaseki-kabe Facies IIIAn almost complete left dentaryKaganaias K. hakusanensisKaseki-kabe Facies III"Part and counterpart of articulated partial skeleton comprising parts of the dors. vert. series and parts of the tail, pelvis, and hind limbs"KuroyuriellaK. mikikoi Kaseki-kabe Facies III"A disarticulated skull on four originally conjoined blocks, an association on two small blocks"KuwajimallaK. kagaensis Kaseki-kabe Facies IIISakurasaurusIndeterminateKaseki-kabe Facies III"Small block with disarticulated association of skull bones, vertebrae, ribs, pelvis and hindlimb bones"ParamacellodidaeIndeterminateKaseki-kabe Facies IIISquamata IndeterminateKaseki-kabe Facies IIIFive distinct taxa

Dinosaurs Dinosaurs reported from the Kuwajima FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImagesAlbalophosaurusA. yamaguchiorum Kaseki-kabeFacies IIIPartial skull and lower jawsDromaeosauridae IndeterminateKaseki-kabeFacies IIIEnantiornithes IndeterminateKaseki-kabeFacies IIIOrnithischiaIndeterminateRight dentary, left maxilla, isolated teethDistinct from AlbalophosaurusSauropoda ("Oharasisaurus")IndeterminateKaseki-kabeFacies IIIToothMATSUOKA H. (2000). Fossils of the Kuwajima "Kasekikabe" (Fossil Bluff): a scientific report on a Neocomian (Early Cretaceous) fossil assemblage of the Kuwajima Formation, Tetori Group, Ishikawa, Japan.StyracosternaIndeterminateMaxillary and dental teeth

Other reptiles Choristoderes reported from the Kuwajima FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImagesTrionychidaeIndeterminateKaseki-kabe TestudinoideaIndeterminateKaseki-kabe SinemydidaeIndeterminateKaseki-kabe OrnithocheiridaeIndeterminateKaseki-kabe GnathosaurinaeIndeterminateKaseki-kabe Dsungaripteroidea?IndeterminateKaseki-kabe

Mammaliamorphs Mammaliamorphs reported from the Kuwajima FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImagesHakusanobaatarH. matsuoi Kaseki-kabeFacies IIIDentary fragments and teethEobaataridHakusanodonH. archaeusKaseki-kabeFacies IIIEutriconodontMontirictusM. kuwajimaensis Kaseki-kabeFacies IIITritylodontidTedoribaatarT. reini Kaseki-kabeFacies III"Fragment of right lower jaw with p4"EobaataridMultituberculata IndeterminateKaseki-kabeFacies III

Invertebrate Paleobiota Invertebrates reported from the Kuwajima FormationGenusSpeciesLocationStratigraphic positionMaterialNotesImagesNipponoridiumB. matsuoiKaseki-KabeMimarachnid hemipteranNipponohaglaN. kagaProphalangopsidKagapsychopsK. araneusPsychopsidColeopteraIndeterminateMargaritiferaM. ogamigoensisPreviously classified as Unio ogamigoensis.NakamuranaiaN. kagaensisTrigonioidoid bivalve; previously considered to be ?Unio ogamigoensis.SphaeriumS. sp.SphaeriidViviparusV. onogoensisViviparidMicromelaniaM.? katoensisPhysidaeIndeterminate, two speciesPupilloideaIndeterminate

See also

List of dinosaur-bearing rock formations

References