Fossil Ammonite

A 1:6 Scale Model of a Devonian Wonder

Ammonoids or Ammonites are extinct Molluscs that roughly resemble our modern day Nautilus cephalopods. They inhabited the early Earth marine ecosystem from the Devonian period to the late Cretaceous period. Rather than being bottom-dwellers, these ancient mariners are thought to have been open-sea swimmers (or, possibly, floaters). While Ammonite shells are widely distributed in the fossil record, very few findings of these animals’ soft body parts have been recorded. Furthermore, there is an incredible diversification in Ammonite shell size and shape. Whereas the earliest Devonian species are relatively small (i.e., approximately 15 – 23-cm in diameter), the species from the late-Jurassic to mid-Cretaceous periods are monsters varying in size from 53 cm to 2 meters in diameter.

The Model

This Ammonite model was created by using a special Unity WebGL app (NOTE: versions are available for Linux, MacOS, Windows, and Web-based) programmed by Alexander Erlich. By using a set of parameter sliders, you can “create” your own custom Ammonite. You can find this Web site here: airlich.de/shell

The result from using this Web tool is a 3D-printable STL file similar to this model. In order to print this model, you will need to make two adjustments in your 3D printing software:

1. Add support to this model.

2. Use a brim (or, wide skirt) for holding this model during printing.

Refer to the included photographs for determining the amount of support and size of brim to add to your model for making a successful print.

Enjoy.

References

An interactive Web site for creating your own Ammonite 3D model: airlich.de/shell

“Morphomechanics and Developmental Constraints in the Evolution of Ammonites Shell Form,” by Alexander Erlich, Derek E. Moulton, Alain Goriely, and Regis Chirat, 2016, Journal for Experimental Zoology (Mol. Dev. Evol.) 00B:1-14.