ammonite acquisition

[expatspain]

Looking through some amonites in a rock shop I felt compelled to purchase this one. Not a single one of my others have markings like this so it has been added to my collection. Are the markings from a type of vegetation?

 

 

 

[Ludwigia]

The patterns are made by the socalled suture lines of the septal lobes/chambers of the phragmocone where they are (or were in this case) attached to the inside of the shell. In between them is mineralized sedimentary infill. Your sample has been sanded and polished down in order to accentuate the pattern. Scroll slowly down this page and you'll learn something about terminology and anatomy of ammonites and cephalopods in general.

[expatspain]

2 hours ago, Ludwigia said:

The patterns are made by the socalled suture lines of the septal lobes/chambers of the phragmocone where they are (or were in this case) attached to the inside of the shell. In between them is mineralized sedimentary infill. Your sample has been sanded and polished down in order to accentuate the pattern. Scroll slowly down this page and you'll learn something about terminology and anatomy of ammonites and cephalopods in general.

Thank you, a very interesting and informative page. I can now include on the label notes that the suture lines are Ammonitic (Placenticeros)