siphuncle sits along the ventral margin of the shell.

Prolecanitids form a relatively small and stable order within the Ammonoidea, with 43 named genera and about 1250 species. They were a long-ranging lineage, surviving for about 108 m.y. stretching from the Devonian-Carboniferous boundary to the Early Triassic. Although not as diverse as their goniatitid contemporaries, the Prolecanitida