Ammonite Fossils

Australiceras jacki (ammonite)

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Paralegoceras texanum (goniatite)

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Macrocephalites bifurcatus (ammonite)

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Muensteroceras oweni (goniatite)

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Muensteroceras oweni detail (goniatite)

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Blandfordiceras wallichi (ammonite and Hindu saligram)

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Blandfordiceras wallichi detail

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Sphenodiscus lenticularis (ammonite)

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Sphenodiscus lenticularis detail (ammonite)

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Acanthoceratites nodosus (ceratite)

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Acanthoceratites nodosus (ceratite)

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Glyptotoxoceras indicum (heteromorph ammonite)

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Schistoceras missouriensis (goniatite)

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Cyclolobus oldhami (goniatite)

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Cyclolobus oldhami detail (goniatite)

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Metalegoceras sundiacum (goniatite)

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Douvilliceras mammillare (ammonite)

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Sagenites minaensis (ammonoid)

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Phylloceras heterophyllum (ammonite)

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Phylloceras heterophyllum detail (ammonite)

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Ammonite and nautiloid fossils have been prized from antiquity for their mesmerizing logarithmic spiral. In Hindu religion they are held sacred as saligram (a Nepali example is included here), a reminder of the unfolding of the universe by Lord Vishnu the creator. They are the shells of extinct cephalopods, related to the modern pearly nautilus. Ammonites and nautiloids are prized by paleontologists because they were widespread on the world's oceans, and evolved rapidly. Even with the great array of geological dating techniques now available, geological age can still be determined more accurately by a single ammonite than by geochemical methods. These ammonites and nautiloids are from the recently acquired Retallack collection. Photography by Win McLaughlin, text by Greg Retallack, and web development by Keith Hamm. Images © Museum of Natural and Cultural History.