| Now extinct, ammonites were relatives of the nautilus. |
| Like the nautilus, ammonites build spiral shells separated into chambers. |
| The chamber wall meets the shell in a suture. |
| Usually smooth curves in the nautilus, sutures in ammonites were complex fractal curves. |
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| Click to enlarge in a new window. |
| One of the classical observations of paleontology is that |
| the apparent complexity of the ammonite sutures is higher for genera that evolved later. |
| The box-counting dimension of the sutures can quantify this observation. |
| However, even then interpretations are not straightforward. |
| Here is a summary of the evidence of Boyajian and Lutz that suture dimension increases with the age when genera appeared. |
| Here is an alternate reading of the data by Gould, together with an elaboration of cosmic significance. |