What is Ammonite?
{{Taxobox | name = Ammonoite | fossil_range = [[Devonian]] {{ndash}} [[Cretaceous]] | image = Asteroceras BW.jpg | image_width = 230px | image_caption = ''Asteroceras'' | regnum = [[Animal]]ia | phylum = [[Mollusca]] | classis = [[Cephalopod]]a | subclassis = '''Ammonoidea''' | subclassis_authority = [[Karl Alfred von Zittel|Zittel]], [[1884]] | subdivision_ranks = [[Order (biology)|Orders]] | subdivision = Anarcestida; Clymeniida; [[Goniatitida]]; Prolecanitida; Ceratitida; Phylloceratida; Lytoceratida; Ammonitida; Ancyloceratina}} [[File:Parapuzosia seppenradensis 3.jpg|thumb|240px|''[[Parapuzosia]] seppenradensis'', the largest known ammonite]] [[file:Didymoceras stevensoni, Late Cretaceous, Pierre Shale Formation, Weston County, Wyoming, USA - Houston Museum of Natural Science - DSC01926.JPG|thumb|150px|The different-shaped ammonite ''[[Didymoceras]] stevensoni'']] [[File:Vitoria - Museo Ciencias Naturales11.JPG|thumb|240px|Some of the variety of ammonite body shapes]] '''Ammonites'''<ref>meaning 'ram-horned', from the Egyptian god [[Amun]].</ref> were [[Ocean|marine]] [[cephalopod]] [[mollusc]]s of the [[Class (biology)|subclass]] '''Ammonoidea'''.<ref>Monks, Neale and Palmer, Phil. 2002. ''Ammonites''. London: [[Natural History Museum]].</ref> Their widely-known [[fossil]]s show a ribbed spiral-form shell, in the end compartment of which lived the tentacled animal. These creatures lived in the seas from at least 400 to 65 million years ago. They became extinct at the [[K/T extinction event]]. Their nearest living relatives are the [[octopus]], [[squid]], [[cuttlefish]] and ''[[Nautilus]]''. Nine orders are recognised in the Ammonoidea: five in the [[Palaeozoic]] and four in the [[Mesozoic]]. == Evolution == Ammonites first appeared in the early [[Devonian]] period. They evolved from a small, straight shelled Bactridian, which was an early [[Nautilus|Nautiloid]]. They quickly evolved