USA Ammonite Hoploscaphites cheyennensis Scaphite アンモナイト ホプロスカフィテス・チェエンネンシス

 An extremely rare ammonite from the Fox hills formation in South Dakota. This is a beautiful specimen of a great species,Hoploscaphites cheyennensis Scaphite, and measures 98 mm.  Specie :Hoploscaphites cheyennensis Scaphite.


During the Upper Cretaceous, a huge shallow inland sea stretched from what currently is the Gulf of Mexico northward and through Canada. Ammonites including members of Ammonita Superfamily Scaphitaceae (the scaphites) were ubuiquitous. The Fox Hills Formation, which spans from Alberta down into Colorado, was formed when the Western Interior Seaway retreated in the late Cretacous. It contains a diverse biota, including Tyrannosauroid dinosaurs like  T-Rex and marine mosasaurs.

Fox Hill scaphites typically exhibit red and/or green hues, and browns, a mixture of red and green. Others are whitish, a nearly uniform mixture of the color spectrum.

The primary diagnostic feature of scaphites is somewhat J-shaped, bauplan, one that is less tightly coiled than most ammonites. They are grouped among the heteromorph ammonites comprising suborder Ancyloceratina, because of these irregularly-coiled shells. The scaphites of Fox Hills Formation are normally found in concretions, like fossils of Mazon Creek, some very large, that weather out from stream beds and hillsides. And like Mazon Creek, exquisite preservation is often found. Some of the different scaphite species exhibit shell ornamentation, including tubercles, sutures, keels, and ribs.

Origin - Fox Hills Formation of South Dakota, USA

Size: 98x85x27mm

Weight: 412g

とても希少なこのアンモナイトはUSAサウスダコタ州フォックスヒルズフォーメーションより産出されました。種類はホプロスカフィテスチェイェンネンシス でとても珍しいスカフィテスです。