Kuwajima Formation | |
---|---|
Stratigraphic range: | |
Unit of | Tetori Group |
Sub-units | Lower Member, Upper Member |
Underlies | Akaiwa Formation |
Overlies | Gomijima Formation |
Lithology | |
Primary | Sandstone, Mudstone |
Location | |
Country | Japan |
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]
The multituberculate mammals Hakusanobaatar matsuoi and Tedoribaatar reini are known from the Kuwajima Formation. [4] A member of Tritylodontidae, Montirictus kuwajimaensis , has also been recovered from the unit. [5]
After Matsuoka et al. (2002) [6]
Fish reported from the Kuwajima Formation | ||||||
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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 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 reported from the Kuwajima Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Monjurosuchus | Indeterminate | Kaseki-kabe | Facies III | |||
Neochoristodera [9] | Indeterminate | Facies I | The first report of a neochoristodere from Japan | |||
Choristodera | Indeterminate | Kaseki-kabe | Facies III |
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" | ||
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 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 |
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 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 |
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 |
Eobaataridae is a family of fossil mammals within the order Multituberculata. Remains are known from the Lower Cretaceous of Europe and Asia. They are among the most derived representatives of the informal suborder "Plagiaulacida", and closely related to Cimolodonta. Most eobaatarids are only known from isolated teeth, though several reasonably complete members are known, including Sinobaatar and Jeholbaatar. The body of Sinobaatar is generalised, while Jeholbaatar displays clear adaptations for scansoriality (climbing) due to its elongated digits. Due to the morphology of the cheek teeth, Eobaatar and Jeholbaatar are inferred to be omnivorous, likely feeding on plants and invertebrates.
Kaganaias is an extinct genus of basal and oldest dolichosaur that lived in what is now Japan during the Early Cretaceous. Kaganaias was semi-aquatic and is the only known aquatic squamate known from before the Cenomanian stage of the Cretaceous. It is also the first to be found in an inland area, instead of on the coast where aquatic squamates are commonly found. Its generic name is derived from Kaga Province, the old name for the Ishikawa Prefecture where the specimens were found, while the species name hakusanensis comes from the mountain that gives its name to Hakusan the city near its find site. The geological formation in which the specimens were found, the Kuwajima Formation, stands alongside the Tetori River and has been the site of numerous other finds including molluscs, dinosaurs, fish, and pterosaurs.
Shokawa is an extinct genus of choristoderan diapsid reptile, known from the Lower Cretaceous of Japan. It is only known from one species, Shokawa ikoi. The only known remains are a postcranial specimen lacking the skull, discovered at the KO2 locality in sediments belonging to the Okurodani Formation near the village of Shokawa in Gifu Prefecture. Shokawa possessed a long neck with at least 16 cervical vertebrae, and closely resembles and is closely related to the smaller choristoderan, Hyphalosaurus. The generic name refers to the village near where it was found, while the specific name honors the collector of the first specimen, one Mr. Ikoi Shibata.
The Kitadani Formation is a unit of Lower Cretaceous sedimentary rock which crops out near the city of Katsuyama in Fukui Prefecture, Japan, and it is the primary source of Cretaceous-aged non-marine vertebrate fossils in Japan. Dinosaur remains are among the fossils that have been recovered from the formation, but it also preserves a diverse assemblage of plants, invertebrates, and other vertebrates. Most, if not all, of the fossil specimens collected from the Kitadani Formation are reposited at the Fukui Prefectural Dinosaur Museum.
Amphidon is an extinct genus of Late Jurassic mammal from the Morrison Formation. It is present in stratigraphic zone five. Two species have been named in the genus: Amphidon superstes and Amphidon aequicrurius, by Simpson in 1925.
Albalophosaurus is a genus of marginocephalian ornithischian dinosaur that lived in Japan during the Early Cretaceous. The type species is Albalophosaurus yamaguchiorum.
The Amagodani Formation is an Early Cretaceous geologic formation in Japan. An indeterminate iguanodontian tooth has been recovered from the formation. as well as indeterminate pterosaur remains. Dinosaur footprints are also known from the formation.
The Okurodani Formation is an Early Cretaceous geologic formation in central Honshu, Japan. Part of the Tetori Group, it primarily consists of freshwater continental sediments deposited in a floodplain environment, with occasional volcanic tuffite horizons. It has an uncertain age, probably dating between the Hauterivian and Aptian. An indeterminate iguanodontian dinosaur tooth has been recovered from the formation. Many other fossil vertebrates are known from the KO2 locality
Monjurosuchus is a genus of choristoderan reptile that lived in what is now China and Japan during the Early Cretaceous. It has large eyes, a rounded skull, robust legs with short claws, and a long, thin tail. Fossils have been found that preserve soft tissue, showing that it had soft skin and webbed feet.
Khurendukhosaurus is a genus of choristodere, a type of amphibious reptile. It is known from Lower Cretaceous rocks of Mongolia and Russia. Two species have been named. The type species, K. orlovi, was named in 1984 by Sigogneau–Russell and Efimov for the fragmentary postcranial skeleton PIN 3386/3. This specimen was discovered in the Albian-age Lower Cretaceous Khuren Dukh Formation Formation at Hüren Dukh, central Mongolia. The lake deposits at this site also contain fossils of the choristoderes Irenosaurus and Tchoiria. Other postcranial bones of K. orlovi have been found at this site as well.
Tchoiria () is a genus of neochoristoderan reptile from the Early Cretaceous of Mongolia. The name Tchoiria comes from the city of Choir which is nearby to where the holotype was found. Tchoiria is thought to have a similar diet to another neochoristoderan reptile, Champsosaurus, due to morphology of the skull. It would hunt in freshwater environments, like the living gharials, where it would prey on many different types of fish and turtles.
Tambatitanis is an extinct genus of titanosauriform, possibly a titanosaurian, sauropod dinosaur from the Early Cretaceous aged Ohyamashimo Formation of the Sasayama Group. It is known from a single species, Tambatitanis amicitiae, known from a partial skeleton.
Nipponoolithus is an oogenus of fossil egg native to Japan. It is one of the smallest known dinosaur eggs, and was probably laid by some kind of non-avian maniraptor.
Montirictus is an extinct genus of tritylodonts known from the Early Cretaceous Kuwajima Formation of Japan. It was among the latest surviving tritylodontids, and is closely related to the earlier Xenocretosuchus from mainland Asia, and the Jurassic Stereognathus from the UK. It may be a species of the genus Stereognathus, but resolution of its affinities conditions upon the discovery of additional material.
Dolichosauridae is a family of Cretaceous aquatic lizards. They are widely considered to be the earliest and most primitive members of Mosasauria, though some researchers have recovered them as more closely related to snakes.
Shirerpeton is an extinct genus of albanerpetontid amphibian from the Early Cretaceous Kuwajima Formation, which is located in Japan. The type species is Shirerpeton isajii, which was described by Masumoto & Evans in 2018. Shirerpeton represents the first record of Albanerpetontidae in East Asia and the holotype is SBEI 2459, a small block bearing most of a disarticulated but associated skull with some postcranial elements present as well.
Hakusanobaatar is an extinct genus of eobaatarid multituberculate that existed in Japan during the early Cretaceous.
The Tetori Group is a stratigraphic group in Japan, found within several basins in and around Fukui Prefecture. It is Early Cretaceous in age. It primarily consists of freshwater continental deposits, with some beds of volcanic tuffite. It primarily overlies Jurassic marine sediments or gneiss basement. Some of the units within the group are noted for their fossil content, including dinosaurs, lizards mammals and other vertebrates.
Fossiomanus is an extinct genus of tritylodontid mammaliamorphs from the Early Cretaceous of China. It includes one species, F. sinensis, which is known from a single nearly complete skeleton from the Aptian Jiufotang Formation. Features of its limbs and vertebrae indicate that Fossiomanus was adapted towards a fossorial lifestyle.