page_title: List of ammonite genera
section_title: Sy
hierarchical_section_title: List of ammonite genera / S / Sy
caption_attribution_description: English: Reconstructions of two species of the heteromorph ammonite genus Shastoceras behemoth (the larger), and S. californicum (the smaller), of Aptian California (C) Stanton F. Fink
context_page_description: This list of ammonites is a comprehensive listing of genera that are included in the subclass †Ammonoidea, excluding purely vernacular terms. The list includes genera that are commonly accepted as valid, as well those that may be invalid or doubtful, or were not formally published, as well as junior synonyms of more established names, and genera that are no longer considered ammonites.
context_section_description: Sympolycyclus
  Synartinskia
  Syngastrioceras
  Synpharciceras
  Synuraloceras
  Synwocklumeria
  Syrdenites
caption: Shastoceras behemothi (front) and Annuloceras summersi (background)
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