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. Images © Museum of Natural and Cultural History.
Ammonite, Australiceras jacki
Wrotham Park, Queensland, Blackdown Formation
Early Cretaceous (Aptian) - Specimen #P3835A
Ammonite, Australiceras jacki
Wrotham Park, Queensland, Blackdown Formation
Early Cretaceous (Aptian) - Specimen #P3835A
Goniatite, Paralegoceras texanum
Bend, Texas, Smithwick Shale
Early Pennsylvanian - Specimen #P9569
Goniatite, Paralegoceras texanum
Bend, Texas, Smithwick Shale
Early Pennsylvanian - Specimen #P9569
Ammonite, Macrocephalites bifurcatus
Telfomin, Papua, Telefomine Beds
Middle Jurassic (Callovian) - Specimen #P3852
Ammonite, Macrocephalites bifurcatus
Telfomin, Papua, Telefomine Beds
Middle Jurassic (Callovian) - Specimen #P3852
Goniatite, Muensteroceras oweni
Rockford, Indiana, Rockford Formation,
Mississippian (Kinderhookian) - Specimen #P6372A
Goniatite, Muensteroceras oweni
Rockford, Indiana, Rockford Formation,
Mississippian (Kinderhookian) - Specimen #P6372A
Goniatite detail, Muensteroceras oweni
Rockford, Indiana, Rockford Formation
Mississippian (Kinderhookian) - Specimen #P6372A
Goniatite detail, Muensteroceras oweni
Rockford, Indiana, Rockford Formation
Mississippian (Kinderhookian) - Specimen #P6372A
Ammonite and Hindu saligram, Blandfordiceras wallichi
Jomosom, Nepal, Saligram Formation
Late Jurassic (Tithonian) - Specimen #P6478
Ammonite and Hindu saligram, Blandfordiceras wallichi
Jomosom, Nepal, Saligram Formation
Late Jurassic (Tithonian) - Specimen #P6478
Ammonite and Hindu saligram detail, Blandfordiceras wallichi
Jomosom, Nepal, Saligram Formation
Late Jurassic (Tithonian) - Specimen #P6478
Ammonite and Hindu saligram detail, Blandfordiceras wallichi
Jomosom, Nepal, Saligram Formation
Late Jurassic (Tithonian) - Specimen #P6478
Ammonite, Sphenodiscus lenticularis
Scenic, South Dakota, Pierre Shale
Late Cretaceous (Maastrichtian) - Specimen #P6516
Ammonite, Sphenodiscus lenticularis
Scenic, South Dakota, Pierre Shale
Late Cretaceous (Maastrichtian) - Specimen #P6516
Ammonite detail, Sphenodiscus lenticularis
Scenic, South Dakota, Pierre Shale
Late Cretaceous (Maastrichtian) - Specimen #P6516
Ammonite detail, Sphenodiscus lenticularis
Scenic, South Dakota, Pierre Shale
Late Cretaceous (Maastrichtian) - Specimen #P6516
Ceratite, Acanthoceratites nodosus
Heimsheim, Germany, Muschelkalk
Middle Triassic (Ladinian) - Specimen #P8374
Ceratite, Acanthoceratites nodosus
Heimsheim, Germany, Muschelkalk
Middle Triassic (Ladinian) - Specimen #P8374
Ceratite, Acanthoscaphites nodosus
Fort Peck, Montana, Bearpaw Shale
Late Cretaceous (Maastrichtian) - Specimen #P8862
Ceratite, Acanthoscaphites nodosus
Fort Peck, Montana, Bearpaw Shale
Late Cretaceous (Maastrichtian) - Specimen #P8862
Heteromorph ammonite, Glyptotoxoceras indicum
Pape Place, California, Chico Formation
Late Cretaceous (Campanian) - Specimen #P9476
Heteromorph ammonite, Glyptotoxoceras indicum
Pape Place, California, Chico Formation
Late Cretaceous (Campanian) - Specimen #P9476
Goniatite, Schistoceras missouriensis
Bridgeport, Texas, Wolf Mountain Shale
Pennsylvanian (Missourian) - Specimen #P10864
Goniatite, Schistoceras missouriensis
Bridgeport, Texas, Wolf Mountain Shale
Pennsylvanian (Missourian) - Specimen #P10864
Goniatite, Cyclolobus oldhami
Ambilobe, Madagascar, Sakamena Group
Late Permian (Changsingian) - Specimen #P12977B
Goniatite, Cyclolobus oldhami
Ambilobe, Madagascar, Sakamena Group
Late Permian (Changsingian) - Specimen #P12977B
Goniatite detail, Cyclolobus oldhami
Ambilobe, Madagascar, Sakamena Group
Late Permian (Changsingian) - Specimen #P12977B
Goniatite detail, Cyclolobus oldhami
Ambilobe, Madagascar, Sakamena Group
Late Permian (Changsingian) - Specimen #P12977B
Goniatite, Metalegoceras sundiacum
Basleo, Timor, Maubisse Formation
Early Permian (Artinskian) - Specimen #P14320
Goniatite, Metalegoceras sundiacum
Basleo, Timor, Maubisse Formation
Early Permian (Artinskian) - Specimen #P14320
Ammonite, Douvilliceras mammillare
Majunga, Madagascar, Ambarimaniya Formation
Early Cretaceous (Albian) - Specimen #P15359
Ammonite, Douvilliceras mammillare
Majunga, Madagascar, Ambarimaniya Formation
Early Cretaceous (Albian) - Specimen #P15359
Ammonoid, Sagenites minaensis
Union Canyon, Nevada, Luning Formation
Late Triassic (Carnian) - Specimen #P15039
Ammonoid, Sagenites minaensis
Union Canyon, Nevada, Luning Formation
Late Triassic (Carnian) - Specimen #P15039
Ammonite, Phylloceras heterophyllum
Majunga, Madagascar, Beronono Formation
Early Jurassic (Toarcian) - Specimen #P15778
Ammonite, Phylloceras heterophyllum
Majunga, Madagascar, Beronono Formation
Early Jurassic (Toarcian) - Specimen #P15778
Ammonite detail, Phylloceras heterophyllum
Majunga, Madagascar, Beronono Formation
Early Jurassic (Toarcian) - Specimen #P15778
Ammonite detail, Phylloceras heterophyllum
Majunga, Madagascar, Beronono Formation
Early Jurassic (Toarcian) - Specimen #P15778
