The Ammonellipsitinae is a subfamily (one of two) within the Pericyclidae

Pericyclidae

Pericyclidae is one of nine families of the Pericyclaceae superfamily. They are an extinct group of ammonoid, which are shelled cephalopods related to squids, belemnites, octopuses, and cuttlefish, and more distantly to the nautiloids.-References:...

, a family within the goniatitid superfamily Pericyclaceae

Pericyclaceae

Pericyclaceae is one of seventeen superfamilies of the Goniatitina suborder. They are an extinct group of ammonoid, which are shelled cephalopods related to squids, belemnites, octopodes, and cuttlefish, and more distantly to the nautiloids.-References:...

 from the Lower Carboniferous

Carboniferous

The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

(Mississippian) characterized by having a suture in which the sides of the ventral lobe diverge and the first lateral saddle is acute or subacute, and in which the immature and juvenile shell has a wide umbilucus.

Of the four genera so far included, Fascipericyclus, Helicocyclus, and Stenocyclus were once considered subgenera of Pericyclus. The type genus, Ammonellisites was also included in the older Pericylitinae that was part of the Goniatitidae in Miller et al. (1960)

Ammonellipsitinae have been found mostly in Europe but some have been found in North America (U.S.A.) as well