ammonite01
Australiceras jacki (ammonite)
1 of 20
ammonite02
Paralegoceras texanum (goniatite)
2 of 20
ammonite03
Macrocephalites bifurcatus (ammonite)
3 of 20
ammonite04
Muensteroceras oweni (goniatite)
4 of 20
ammonite05
Muensteroceras oweni detail (goniatite)
5 of 20
ammonite06
Blandfordiceras wallichi (ammonite and Hindu saligram)
6 of 20
ammonite07
Blandfordiceras wallichi detail
7 of 20
ammonite08
Sphenodiscus lenticularis (ammonite)
8 of 20
ammonite09
Sphenodiscus lenticularis detail (ammonite)
9 of 20
ammonite10
Acanthoceratites nodosus (ceratite)
10 of 20
ammonite11
Acanthoceratites nodosus (ceratite)
11 of 20
ammonite12
Glyptotoxoceras indicum (heteromorph ammonite)
12 of 20
ammonite13
Schistoceras missouriensis (goniatite)
13 of 20
ammonite14
Cyclolobus oldhami (goniatite)
14 of 20
ammonite15
Cyclolobus oldhami detail (goniatite)
15 of 20
ammonite16
Metalegoceras sundiacum (goniatite)
16 of 20
ammonite17
Douvilliceras mammillare (ammonite)
17 of 20
ammonite18
Sagenites minaensis (ammonoid)
18 of 20
ammonite19
Phylloceras heterophyllum (ammonite)
19 of 20
ammonite20
Phylloceras heterophyllum detail (ammonite)
20 of 20

View the entire gallery or click on the above images to enlarge.

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.