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shell3

The Mathematical Study of Mollusk Shells


3. Nautilus and the Ammonites

Not many shells exhibit the logarithmic spiral in its simplest, planar form. The main living example is the cephalopod Nautilus pompilius. There are many examples (all extinct) in the cephalopod subclass Ammonoidea.

Nautilus 5
Shell of Nautilus pompilius sliced acrossto show inner chambers. Image from Sanibel Seashell Industries, used with permission.
Maple Nautilus
A mathematical model of Nautilus.Model details.
Ammonite Astroceras Obtusum
Fossil of the Ammonite Astroceras obtusum.Image from Paleopalace.com,used with permission. This specimen, measuring approx. 4 inchesin diameter, is from the lower Lias formation in Dorset, England.It is about 200 million years old.
Model of Astroceras
A mathematical model of Astroceras.
Model details.



Ammonite Euhoplites truncatus
Fossil Ammonite Euhoplites truncatus.Image @2000 Jim Craig from Fossils of the GaultClay and Folkestone Beds of Kent, UK, used with permission.
Model of Euhoplites
A mathematical model of Euhoplites.
Model details.


Fossil Bellerophina minuta
Fossil Bellerophina minuta. Long thought tobe a cephalopod, recently reclassified in the Gastropoda.Image @2000 Jim Craig from Fossils of the GaultClay and Folkestone Beds of Kent, UK, used with permission.
Model of Bellerophina
A mathematical model of Bellerophina.
Model details.




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