See text Gymnitidae is a family of Lower to Middle Triassic ammonite cephalopods with evolute, discoidal shells.

The more primitive Xenaspis, Flemingites, and Ophiceras, found in Lower Triassic beds in western America have ceratitic sutures.

The more developed Gymnites has deeply digitate ammonitic sutures.

Arkell, et al., 1957, in the Treatise on Invertebrate Paleontology, on the other hand included the Gymnitidae in the Pinacocerataceae as the earlier and more primitive of its two families, combining Gymnites with coeval and more advanced forms.

Whether to place the Gymnitidae in the Ceratitaceae, as in Hyatt and Smith, combining Gymnites with its more primitive relatives, or in the Pinacocerataceae, as in Arkell et al., combining Gymnites with its coeval or more advanced relatives is a matter of perspective which does little to change the overall phylogeny.