Your ammonite probably is...
Xenodiscus
Suture: Ceratitic
Xenodiscus was a Permian ceratite. It had less obvious radial ribs and simpler suture lines than its relative Ceratites.
Image by Ghedoghedo, licensed under GDFL, CC BY-SA 3.0 unported, 2.5 Generic, 2.0 Generic, and 1.0 Generic. https://commons.wikimedia.org/wiki/File:Xenodiscus_besairiei.JPG