Here is another ammonite from near Poitiers, Vienne Department, France. It's Lissoceratoides erato and is from Oxfordian aged rocks (Jurassic).
The whorls are wide and overlap each other quite a bit so that there is
just a small area in the center that gives evidence of previous shell. It is a fairly flat shell in cross section.
Here is a closeup of the shell and the visible sutures...
..and an image of the pattern lain flat.
Suture pattern image taken from "Renz O, Imlay R, Lancelot Y, Ryan WBF (1975)
Ammonite rich Oxfordian limestones from the base of the continental slope
off Northwest Africa. Eclogae geol Helv Vol 68 /2: 431–448"