Fontannesia

Fontannesia is an ammonoid cephalopod genus with a small to medium size, evolute, discoidal shell that was extant during the Jurassic Period. The sides are ribbed, the venter has a single median keel, and tubercles are lacking.
"Fontannesia" is included in the Sonniniidae (Hildoceratoidea) and has been found widespread in Europe, western Australia, Canada, and Argentina.