- Source: Eubostrychoceras
Eubostrychoceras is a genus of helically wound, corkscrew form, heteromorph ammonite which lived during the Upper Cretaceous (M Turonian - Campanian). The genus is included in the ancycleratid family Nostoceratidae.
The shell of Eubostrychoceras is a loosely to tightly wound spiral forming a corkscrew with an open, empty umbilicus in the middle. Coiling is commonly dextral (right hand). Coils are covered by moderately strong, straight transverse ribs. The aperture, or apertural end, reverses general direction and points upwards or back towards to apex. Sutures are moderately complex. The siphuncle is located mid flank.
Eubostrychoceras has a widespread distribution in the Upper Createous and has been found in Antarctica, Japan, Spain, the far east of Russia, Alaska, Vancouver Island, U.S. Western Interior Seaway, Germany, and Madagascar.
In 2001 it was reported from Alaska's Matanuska Formation as well. E. japonicum is Turonian, and likely confined to the middle Turonian. Based on the similarity of textures and the curl of the shell as well as the stratigraphic relationships, E. valdelaxum from Japan is likely evolved from E. japonicum.
Related genera include Anaklinoceras, Bostrychoceras, Didymoceras, and Nostoceras.
References
Further reading
The upper Cretaceous ammonite Eubosrychoceras Matsumoto in the western interior of the United States by Willian A Cobban. U.S. Geological Survey bulletin—1690-A, Pub 1987. (Description and illustrations of an unusual ammonite from Wyoming, South Dakota, and New Mexico)
A New Species of the Heteromorph ammonite Eubostrychoceras from the Upper Cretaceous Frontier Formation, Natrona County, Wyoming. [1]
External links
"Nostoceratidae HYATT 1894". Amonites (in French). Archived from the original on December 7, 2021.
Media related to Eubostrychoceras at Wikimedia Commons
Kata Kunci Pencarian:
- Eubostrychoceras
- Nostoceratidae
- Matanuska Formation
- List of the Mesozoic life of South Dakota
- List of ammonite genera
- List of the Mesozoic life of Alaska
- List of the prehistoric life of Alaska
- List of the prehistoric life of Wyoming
- Santa Marta Formation
- List of the Mesozoic life of Wyoming
