The Akaiwa Formation (Japanese: 赤岩層, romanized: Akaiwa-sō) is an Early Cretaceous (Hauterivian-Barremian) geologic formation in central Honshu, Japan.[1] Indeterminate ornithischian fossils are known from the formation. Fossil ornithopod tracks have been reported from the formation.[2] As well as the turtle Kappachelys[3]
| Akaiwa Formation | |
|---|---|
| Stratigraphic range: Hauterivian-Barremian ~ | |
| Type | Geological formation |
| Unit of | Tetori Group |
| Underlies | Kitadani Formation |
| Overlies | Kuwajima Formation |
| Lithology | |
| Primary | Sandstone, conglomerate |
| Location | |
| Coordinates | 36°12′N 136°42′E / 36.2°N 136.7°E |
| Approximate paleocoordinates | 46°06′N 138°18′E / 46.1°N 138.3°E |
| Region | Honshu |
| Country |  Japan |
  Akaiwa Formation (Japan) | |
Fossil content
editThe following fossils have been reported from the formation:[1]
- Osteichthyes indet. - 'fish scales'
- Reptiles
- Turtles
- Crocodylomorpha indet. - isolated teeth of small crocodiles[4]
- ?Euornithopoda indet.
- Neochoristodera indet. - a nearly complete right premaxilla[5]
- Ornithopoda indet. - isolated teeth of small ornithopods
- ?Theropoda indet.
- Ichnofossils
- Ornithischia indet. - tracks[6]
See also
editReferences
edit- ^ a b Akaiwa Formation in the Paleobiology Database
- ^ Weishampel et al., 2004, pp.517-607
- ^ a b Hirayama et al., 2013
- ^ Matsukawa & Obata, 1994
- ^ Matsumoto et al., 2014
- ^ Azuma & Tomida, 1995
Bibliography
edit- Matsumoto, R.; Manabe, M.; Evans, S. E. (2014), "The first record of a long-snouted chrositodere (Reptilia, Diapsida) from the Early Cretaceous of Isihikawa Prefecture, Japan", Historical Biology, 27: 583–594, doi:10.1080/08912963.2014.898296
- Hirayama, R.; Isaji, S.; Hibino, T. (2013), Kappachelys okurai gen. et sp. nov., a new stem soft-shelled turtle from the Early Cretaceous of Japan. In D. B. Brinkman, P. A. Holroyd, J. D. Gardner, Morphology and Evolution of Turtles, pp. 179–185
- Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004), The Dinosauria, 2nd edition, Berkeley: University of California Press, pp. 1–880, ISBN 0-520-24209-2, retrieved 2019-02-21
- Azuma, Y.; Tomida, Y. (1995), Early Cretaceous dinosaur fauna of the Tetori Group in Japan. In A. Sun, Y. Wang (eds.), Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers, pp. 125–131
- Matsukawa, M.; Obata, I. (1994), "Dinosaurs and sedimentary environments in the Japanese Cretaceous: a contribution to dinosaur facies in Asia based on molluscan palaeontology and stratigraphy", Cretaceous Research, 15 (1): 101–125, Bibcode:1994CrRes..15..101M, doi:10.1006/cres.1994.1005