Prolobitidae is a family of middle and upper

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

ammonoid Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

cephalopods A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, an ...

currently included in the goniatitid suborder

Tornoceratina Tornoceratina is one of two suborders included in the Goniatitida, characterized by generally involute, subdiscoidal shells and by sutures in which the ventral ones are undivided. Sutural lobes increase in number during the course of life of th ...

and superfamily Dimeroceratoidea, but previously included in the ancestral Anarcestida. Prolobitids are characterized by goniatic sutures with an undivided ventral lobe and primary lateral lobes that are introduced in the umbilical region. They have shells which are discoidal to subglobular, some bearing transverse ribs and the umbilicus is generally moderate to closed. Prolobitidae is divided into two subfamilies, Prolobitinae consisting of subglobular to subdiscoidal shells with moderate to closed umbilici, and Raymondoceratinae consisting of discodal shells with transverse ribs and large umbilici. The Prolobitidae have been considered the likely ancestors for

Prolecanitida Prolecanitida is an order of extinct ammonoidea, ammonoid cephalopods with discoidal to thinly lenticular shells with goniatitic or ceratitic sutures and which retained the simple retrochoanitic siphuncle with backward extending septal necks. As ...

References

* Miller, Furnish, and Schindewolf,1957; Paleozoic Ammonoidea, Suborder Anarcestina, L29-L33, in The Treatise on Invertebrate Paleontology, Part L, Ammonoidea.
The Paleobiology Database
as of 10/01/07 Goniatitida families Dimeroceratoidea Middle Devonian first appearances Late Devonian animals Late Devonian extinctions {{Goniatitida-stub