What is "haploceratidae"

The Haploceratidae is one of the families to go to form the Haplocerataceae, a superfamily in the ammonitina; which according to Donovan et al (1981)can be derived from the Taramelliceratinae, a subfamily of the Oppeliidae.

Haploceratids, (Haploceratidae) are typically small, smooth and somewhat featurelss ammonites, as described by Arkell et al, without ribbing or ventral keels and moderately undifferentiated sutures; that range from the Late Kimmeridgian to the Hauterivian, crossing from the Jurassic into the Cretaceous.