The Sonniniidae comprise a diverse family of Middle Jurassic ammonites, (order Ammonitida), ranging from those with stout evolute shells to those whose shells are sharply rimmed, oxyconic. The keel, which runs along the middle of the venter, is typically hollow. Sutures vary from simple to complex. Aptychus is shiny with coarse folds (Cornaptychus). The Sonniniidae are included in the Hildocerataceae. Most lived during the middle Bajocian stage. Distribution is worldwide except for boreal. Genera include Sonninia, type, Dorsetensia, Fissilobiceras, Fontannesia, Guhsania, and Pelekodites.