Kuwajima Formation

Kuwajima Formation
Kuwajima Formation
Stratigraphic range: Barremian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Unit of	Tetori Group
Sub-units	Lower Member, Upper Member
Underlies	Akaiwa Formation
Overlies	Gomijima Formation
Lithology
Primary	Sandstone, Mudstone
Location
Country	Japan

Last updated September 30, 2025

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.^[1] However, it is now considered to probably be Barremian in age.^[2] Dinosaurs and other vertebrates has been recovered from the Kaseki-kabe "Fossil-bluff" locality in the uppermost part of the formation.^[3]

Vertebrate Paleobiota

After Matsuoka et al. (2002)^[6]

Fish

Fish reported from the Kuwajima Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Sinamia	S. kukurihime			Mostly complete skeleton	An amiiform fish related to bowfins
Tetoriichthys	T. kuwajimaensis				The oldest record of Osteoglossiform
Lepidotes	L. sp.
Pachycormidae	Indeterminate			Jaw

Amphibians

Amphibians reported from the Kuwajima Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Shirerpeton ^[7]	S. isajii	Kaseki-kabe	Facies III	Partial disarticulated skull	Albanerpetontid
Anura	Indeterminate			Isolated longbone, as well as a partial skeleton "composed of a few skull elements and several postcranial bones, including the femur, ilium, and vertebrae"^[8]	Partial skeleton belongs to a basal frog that lies outside of Neobatrachia.^[8]

Choristoderes

Choristoderes reported from the Kuwajima Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Monjurosuchus	Indeterminate	Kaseki-kabe	Facies III			Monjurosuchus
Neochoristodera ^[9]	Indeterminate		Facies I		The first report of a neochoristodere from Japan
Choristodera	Indeterminate	Kaseki-kabe	Facies III

Squamates

Squamates reported from the Kuwajima Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Asagaolacerta	A. tricuspidens	Kaseki-kabe	Facies III	"An association of skull, jaws and postcranial bones of a small lizard with facetted tricuspid teeth, possibly a right maxilla"		Kaganaias
Hakuseps	H. imberis	Kaseki-kabe	Facies III	An almost complete left dentary
Kaganaias	K. hakusanensis	Kaseki-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"
Kuroyuriella	K. mikikoi	Kaseki-kabe	Facies III	"A disarticulated skull on four originally conjoined blocks, an association on two small blocks"
Kuwajimalla ^[10]	K. kagaensis	Kaseki-kabe	Facies III
Sakurasaurus	Indeterminate	Kaseki-kabe	Facies III	"Small block with disarticulated association of skull bones, vertebrae, ribs, pelvis and hindlimb bones"
Paramacellodidae	Indeterminate	Kaseki-kabe	Facies III
Squamata	Indeterminate	Kaseki-kabe	Facies III		Five distinct taxa

Dinosaurs

Dinosaurs reported from the Kuwajima Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Albalophosaurus ^[3]	A. yamaguchiorum	Kaseki-kabe	Facies III	Partial skull and lower jaws
Dromaeosauridae	Indeterminate	Kaseki-kabe	Facies III
Enantiornithes	Indeterminate	Kaseki-kabe	Facies III
Ornithischia ^[11]	Indeterminate			Right dentary, left maxilla, isolated teeth	Distinct from Albalophosaurus
Sauropoda ("Oharasisaurus")	Indeterminate	Kaseki-kabe	Facies III		Tooth^[12]
Styracosterna ^[11]	Indeterminate			Maxillary and dental teeth

Other reptiles

Choristoderes reported from the Kuwajima Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Trionychidae	Indeterminate	Kaseki-kabe
Testudinoidea	Indeterminate	Kaseki-kabe
Sinemydidae	Indeterminate	Kaseki-kabe
Ornithocheiridae	Indeterminate	Kaseki-kabe
Gnathosaurinae	Indeterminate	Kaseki-kabe
Dsungaripteroidea?	Indeterminate	Kaseki-kabe

Mammaliamorphs

Mammaliamorphs reported from the Kuwajima Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Hakusanobaatar ^[4]	H. matsuoi	Kaseki-kabe	Facies III	Dentary fragments and teeth	Eobaatarid
Hakusanodon ^[13]	H. archaeus	Kaseki-kabe	Facies III		Eutriconodont
Montirictus ^[5]	M. kuwajimaensis	Kaseki-kabe	Facies III		Tritylodontid
Tedoribaatar ^[4]	T. reini	Kaseki-kabe	Facies III	"Fragment of right lower jaw with p4"	Eobaatarid
Multituberculata	Indeterminate	Kaseki-kabe	Facies III

Invertebrate Paleobiota

Invertebrates reported from the Kuwajima Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Nipponoridium	B. matsuoi	Kaseki-Kabe			Mimarachnid hemipteran
Nipponohagla	N. kaga				Prophalangopsid
Kagapsychops	K. araneus				Psychopsid
Coleoptera	Indeterminate
Unio	U. ogamigoensis				Unionid
Sphaerium	S. sp.				Sphaeriid
Viviparus	V. onogoensis				Viviparid
Micromelania	M.? katoensis				Sphaeriid
Physidae	Indeterminate, two species
Pupilloidea	Indeterminate

References

↑ Fujita, M. (2003). "Geological age and correlation of the vertebrate-bearing horizons in the Tetori Group". Memoir of the Fukui Prefectural Dinosaur Museum. 2: 3–14.
↑ Amiot, Romain; Kusuhashi, Nao; Saegusa, Haruo; Shibata, Masateru; Ikegami, Naoki; Shimojima, Shizuo; Sonoda, Teppei; Fourel, François; Ikeda, Tadahiro; Lécuyer, Christophe; Philippe, Marc; Wang, Xu (2021-01-01). "Paleoclimate and ecology of Cretaceous continental ecosystems of Japan inferred from the stable oxygen and carbon isotope compositions of vertebrate bioapatite". Journal of Asian Earth Sciences. 205 104602. Bibcode:2021JAESc.20504602A. doi: 10.1016/j.jseaes.2020.104602 . ISSN 1367-9120.
1 2 Ohashi, T.; Barrett, P. M. (2009). "A new ornithischian dinosaur from the Lower Cretaceous Kuwajima Formation of Japan". Journal of Vertebrate Paleontology. 29 (3): 748–757. Bibcode:2009JVPal..29..748O. doi:10.1671/039.029.0306. S2CID 128546047.
1 2 3 Kusuhashi, Nao (September 2008). "Early Cretaceous Multituberculate Mammals from the Kuwajima Formation (Tetori Group), Central Japan". Acta Palaeontologica Polonica. 53 (3): 379–390. doi: 10.4202/app.2008.0302 . ISSN 0567-7920.
1 2 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:
↑ Hiroshige, MATSUOKA; Nao, KUSUHASHI; Takahiro, TAKADA; Takeshi, SETOGUCHI (2002). "A clue to the Neocomian vertebrate fauna: initial results from the Kuwajima ""Kaseki-kabe"" (Tetori Group) in Shiramine, Ishikawa, central Japan". Memoirs of the Faculty of Science, Kyoto University, Series of Geology and Mineralogy. 59 (1): 33–45.
↑ Matsumoto, Ryoko; Evans, Susan E. (2018-01-03). "The first record of albanerpetontid amphibians (Amphibia: Albanerpetontidae) from East Asia". PLOS ONE. 13 (1) e0189767. Bibcode:2018PLoSO..1389767M. doi: 10.1371/journal.pone.0189767 . ISSN 1932-6203. PMC 5752013 . PMID 29298317.
1 2 Mizukami, Ayano; Matsumoto, Ryoko; Wani, Ryoji; Evans, Susan E. (2023-01-04). "A Three-Dimensionally Preserved Frog (Amphibia, Anura) from the Lower Cretaceous Kuwajima Formation, Tetori Group, Ishikawa Prefecture, Japan" . Paleontological Research. 27 (3). doi:10.2517/PR210031. ISSN 1342-8144.
↑ Matsumoto, Ryoko; Manabe, Makoto; Evans, Susan E. (2015-07-04). "The first record of a long-snouted choristodere (Reptilia, Diapsida) from the Early Cretaceous of Ishikawa Prefecture, Japan". Historical Biology. 27 (5): 583–594. Bibcode:2015HBio...27..583M. doi:10.1080/08912963.2014.898296. ISSN 0891-2963.
↑ Evans, Susan E.; Manabe, Makoto (March 2008). "An early herbivorous lizard from the Lower Cretaceous of Japan". Palaeontology. 51 (2): 487–498. Bibcode:2008Palgy..51..487E. doi: 10.1111/j.1475-4983.2008.00759.x . ISSN 0031-0239.
1 2 Barrett, Paul M.; Ohashi, Tomoyuki (October 2015). "Ornithischian dinosaur material from the Kuwajima Formation (Tetori Group: Lower Cretaceous) of Ishikawa Prefecture, Japan". Historical Biology. 28 (1–2): 280–288. doi:10.1080/08912963.2015.1032273. ISSN 0891-2963. S2CID 128909019.
↑ MATSUOKA 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.
↑ Rougier, Guillermo W.; Isaji, Shinji; Manabe, Makoto (2007). "An Early Cretaceous Mammal from the Kuwajima Formation (Tetori Group), Japan, and a Reassessment of Triconodont Phylogeny" . Annals of Carnegie Museum. 76 (2): 73. doi:10.2992/0097-4463(2007)76[73:aecmft]2.0.co;2. ISSN 0097-4463.

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[FM03-1] Fujita, M. (2003). "Geological age and correlation of the vertebrate-bearing horizons in the Tetori Group". Memoir of the Fukui Prefectural Dinosaur Museum. 2: 3–14.

[2] Amiot, Romain; Kusuhashi, Nao; Saegusa, Haruo; Shibata, Masateru; Ikegami, Naoki; Shimojima, Shizuo; Sonoda, Teppei; Fourel, François; Ikeda, Tadahiro; Lécuyer, Christophe; Philippe, Marc; Wang, Xu (2021-01-01). "Paleoclimate and ecology of Cretaceous continental ecosystems of Japan inferred from the stable oxygen and carbon isotope compositions of vertebrate bioapatite". Journal of Asian Earth Sciences. 205 104602. Bibcode:2021JAESc.20504602A. doi: 10.1016/j.jseaes.2020.104602 . ISSN 1367-9120.

[OB09-3] 1 2 Ohashi, T.; Barrett, P. M. (2009). "A new ornithischian dinosaur from the Lower Cretaceous Kuwajima Formation of Japan". Journal of Vertebrate Paleontology. 29 (3): 748–757. Bibcode:2009JVPal..29..748O. doi:10.1671/039.029.0306. S2CID 128546047.

[:0-4] 1 2 3 Kusuhashi, Nao (September 2008). "Early Cretaceous Multituberculate Mammals from the Kuwajima Formation (Tetori Group), Central Japan". Acta Palaeontologica Polonica. 53 (3): 379–390. doi: 10.4202/app.2008.0302 . ISSN 0567-7920.

[:1-5] 1 2 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:

[6] Hiroshige, MATSUOKA; Nao, KUSUHASHI; Takahiro, TAKADA; Takeshi, SETOGUCHI (2002). "A clue to the Neocomian vertebrate fauna: initial results from the Kuwajima ""Kaseki-kabe"" (Tetori Group) in Shiramine, Ishikawa, central Japan". Memoirs of the Faculty of Science, Kyoto University, Series of Geology and Mineralogy. 59 (1): 33–45.

[7] Matsumoto, Ryoko; Evans, Susan E. (2018-01-03). "The first record of albanerpetontid amphibians (Amphibia: Albanerpetontidae) from East Asia". PLOS ONE. 13 (1) e0189767. Bibcode:2018PLoSO..1389767M. doi: 10.1371/journal.pone.0189767 . ISSN 1932-6203. PMC 5752013 . PMID 29298317.

[:3-8] 1 2 Mizukami, Ayano; Matsumoto, Ryoko; Wani, Ryoji; Evans, Susan E. (2023-01-04). "A Three-Dimensionally Preserved Frog (Amphibia, Anura) from the Lower Cretaceous Kuwajima Formation, Tetori Group, Ishikawa Prefecture, Japan" . Paleontological Research. 27 (3). doi:10.2517/PR210031. ISSN 1342-8144.

[9] Matsumoto, Ryoko; Manabe, Makoto; Evans, Susan E. (2015-07-04). "The first record of a long-snouted choristodere (Reptilia, Diapsida) from the Early Cretaceous of Ishikawa Prefecture, Japan". Historical Biology. 27 (5): 583–594. Bibcode:2015HBio...27..583M. doi:10.1080/08912963.2014.898296. ISSN 0891-2963.

[10] Evans, Susan E.; Manabe, Makoto (March 2008). "An early herbivorous lizard from the Lower Cretaceous of Japan". Palaeontology. 51 (2): 487–498. Bibcode:2008Palgy..51..487E. doi: 10.1111/j.1475-4983.2008.00759.x . ISSN 0031-0239.

[:2-11] 1 2 Barrett, Paul M.; Ohashi, Tomoyuki (October 2015). "Ornithischian dinosaur material from the Kuwajima Formation (Tetori Group: Lower Cretaceous) of Ishikawa Prefecture, Japan". Historical Biology. 28 (1–2): 280–288. doi:10.1080/08912963.2015.1032273. ISSN 0891-2963. S2CID 128909019.

[12] MATSUOKA 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.

[13] Rougier, Guillermo W.; Isaji, Shinji; Manabe, Makoto (2007). "An Early Cretaceous Mammal from the Kuwajima Formation (Tetori Group), Japan, and a Reassessment of Triconodont Phylogeny" . Annals of Carnegie Museum. 76 (2): 73. doi:10.2992/0097-4463(2007)76[73:aecmft]2.0.co;2. ISSN 0097-4463.

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