USA Ammonite Ammolite Sphenodiscus sp & Hoploscaphites Scaphite アンモナイト スフェノディスカス & ホプロスカフィテス

スフェノディスカス & ホプロスカフィテス 

Origin :Fox Hills Formation-South Dakota, USA

スフェノディスカスSize: 約135x114mm



Weight: 2806g





とても希少なこのアンモナイトはUSAサウスダコタ州より産出されました。種類はスフェノディスカス、アンモナイト、アンモライト化しており、美しいレッド発色とともに、パープル・ブルーカラーもみえます。また更に  ホプロスカフィテスが一緒に母岩に入っている とてもレアなディスプレイピースです。



Sphenodiscus is an extinct genus of acanthoceratacean ammonite. The genus has been found from many continents and is thought to have had a large global distribution during the Maastrichtian stage of the Late Cretaceous. It was one of the last ammonoids to have evolved before the entire subclass became extinct at the end of the period during the Cretaceous–Paleogene extinction event.


This is a large, Sphenodiscus splendens ammonite from the Fox Hills Formation that has a brilliant red iridescent shell. This beautiful iredescent shell is basically the same as the Ammolite (name trademarked) from Alberta.certain species at different stages of ontogenic development may possess many small tubercles along their surfaces.  Sphenodiscus had a complex suture pattern with many small branching lobes and saddles.


An extremely rare ammonite from the Fox hills formation in South Dakota. Ammonite and many other small fossils and impressions,clams, ammonites.


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.


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