Panorama of Fractals and Their Uses

Ammonite Sutures

One of the classical observations of paleontology is that the apparent complexity of the ammonite sutures increases with time:

The later a particular ammonite evolved, the more complex its sutures.   Boyajian and Lutz quantified this observation by using the box-countng dimension of the sutures of all 615 genera of ammonites. Dimensions ranged from slightly above 1.0 for the earliest ammonites, to over 1.6 for the last ammonites.   The common interpretation is that suture dimension increased as the ammonites evolved. Perhaps the greater sinuosity associated with higher dimension strengthened the shell, or perhaps it provided more area to attach muscles.

The variations of complexity are illustrated by these pictures from the Moore's Treatise on Invertebrate Paleontology. Click on each picture to enlarge in a new window.

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