Here is a very classical Ammonite that should not ben missed in any collection.
The Ammonites that been found Dewey County in South Dakota are known for there super nice iridescent preservation of the mother of pearl shell. That is specialy on the species Jeletzkytes nebrascensis very well preserved.  This specimen does have a impressive diameter of about 78 mm. This with speices that is also characterised by the strong nodes on the shell is known by different synonyms.

[ Syn. : Hoploscaphites nebrascensis, Discoscaphites nebrascensis , Scaphites nebrascens ]

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