Perisphinctaceae

The Perisphinctaceae, Perisphinctoidea in newer references, is a superfamily of ammonites that unites a dozen (12) or so phylogenetically related families, namely the: Aspidoceratidae, Aulacostephanidae, Dorsoplanitidae, Himalayitidae, Holcodiscidae, Morphoceratidae, Olcostephaidae, Parkinsoniidae, Perisphinctidae, Polyptychitidae, Reineckeiidae, and Tulitidae. The actual families considered included vary somewhat from reference to reference.

General description
Perisphinctacean shells are typically evolute and strongly ribbed. Diagnostic specifics such as character of ribbing and degree of whorl overlap varies from family to family and from genus to genus.

A phylogeny
According to J.H. Callomon, 1981, the ancestral Perisphinctidae which form the root stock of the Parisphinctaceae have their origin in the Stephanoceratidae (Stephanocerataceae) with the Perisphinctidae giving rise to the Morphoceratidae in the Bathonian; to the Tulitidae, Reineckeiidae, Pachyceratidae, and Aspidoceratidae in the following Callovian; to the Aulacostephanidae and Ataxoceratidae in the late Oxfordian-early Kimmeridgian, and to the Simoceratidae, Himalayitidae, and Olcostephanidae in the Tithonian near the end of the Jurassic. From the Ataxioceratidae during the Kimmeridgian came the Dorsoplanitidae and Virgatitidae and near the end of the Tithonian, the Neocomitidae. Also, the Dorsoplanitidae give rise to the Craspeditidae late in the Kimmeridgian. The Craspeditidae and Neocomitidae are all but entirely Lower Cretaceous in age, and the Olcostephanidae mostly. The Himalayitidae ranges from the Tithonian to the Berriasian. The Olcostephanidae, derived from the Perisphinctidae gave rise, at the end of its range in the Hauterivian, to he Holcodiscidae, the last of the perisphintaceans.