Sphenodiscus
Sphenodiscus Wani barewa ne na acanthoceratacean ammonite. An samo nau'in jinsin daga nahiyoyi da yawa kuma ana tunanin ya sami babban rarraba a duniya a lokacin Maastrichtian mataki na Late Cretaceous.Ya kasance ɗaya daga cikin ammonoids na ƙarshe da suka samo asali kafin gabaɗayan rukunin su zama batattu a lokacin Paleocene, wanda ya kasance kai tsaye bayan taron bacewar Cretaceous–Paleogene.
| Sphenodiscus | |
|---|---|
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| Scientific classification | |
| Kingdom | Animalia |
| Phylum | Mollusca (en)  |
| Class | Cephalopod (en) |
| Order | Ammonitida (en) |
| Dangi | Sphenodiscidae (en)
|
genus (en)  | Sphenodiscus Meek 1871
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| Sphenodiscus | |
|---|---|
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| Sphenodiscus lenticularis | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | †Ammonoidea |
| Order: | †Ammonitida |
| Family: | †Sphenodiscidae |
| Genus: | †Sphenodiscus Meek 1871 |
| Species | |
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An gano burbushin halittu a ko'ina cikin Arewacin Amirka daga yankuna a Kudancin Carolina,[1] North Carolina, South Dakota,[2] Maryland,[3] New Jersey[4] da Mexico.[5] Har ila yau,akwai shaidar jinsin da ke kasancewa daga tsibirin Trinidad,ko da yake ba za a iya rarraba kayan da aka samo daga nan ba a matakin jinsin.[6] Yawancin nau'ikan da ake samu a Arewacin Amurka sun haɗa da S.lobatus,S.lenticularis, da S.pleurisepta . An samo sabbin nau'ikan daga yankuna a wajen Arewacin Amurka kamar S.binkhorsti daga Tsarin Maastricht a cikin Netherlands,S.siva daga Tsarin Valudavur a Indiya da S.brasiliensis daga gadaje tare da bankunan Rio Gramame a Brazil.[7] [8] [9] An kuma sami samfurori da yawa na S.lobatus daga Nkporo Shale a Najeriya.
An daidaita harsashi na Sphenodiscus kuma daga baya an matse shi tare da magudanar ruwa da ƙaramar cibiya.Gefen huhu na harsashi yana mai da hankali sosai.Filayen waje gabaɗaya santsi ne a cikin samfuran burbushin halittu,kodayake wasu nau'ikan a matakai daban-daban na ci gaban ontogenic na iya mallakar ƙananan tubercles masu yawa tare da saman su.[10] Sphenodiscus yana da tsari mai sarƙaƙƙiya mai sarƙaƙƙiya tare da ƙananan ƙananan lobes da sirdi masu yawa.