The Haploceratidae is the type family of the

Haploceratoidea Haploceratoidea, formerly Haplocerataceae, is an extinct superfamily of Ammonoidea, ammonoid cephalopods belonging to the Ammonitida that unites three families, Strigoceratidae, Oppeliidae, and Haploceratidae, listed below. Haploceratoidea begins ...

, a superfamily in the

ammonitina Ammonitina comprises a diverse suborder of ammonite cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils, and it is often possible to link the rock layer in which they are found t ...

; which according to Donovan ''et al.'' (1981) can be derived from the Taramelliceratinae, a subfamily of the

Oppeliidae Oppeliidae are compressed to oxyconic, sculptured Haploceratoidea, either unkeeled, unicarinate, bicarinate, or tricarinate; with sutures in great variety, but ribbing usually more or less falcoid or falcate. The Oppeliidae is the principal famil ...

. Haploceratids, (Haploceratidae) are typically small, smooth and somewhat featureless ammonites, as described by Arkell ''et al'', without ribbing or ventral keels and moderately undifferentiated sutures; that range from the Late

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

to the

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by the Va ...

, crossing from the Jurassic into the Cretaceous.

References

Arkell ''et al.'', 1957 Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology Part L. Geol Society of America and Univ Kansas Press R.C Moore (ed) D.T Donavan, J.H. Callomon, and M.K Howarth. 1981. Classification of the Jurassic Ammonitina. In The Ammonoidea. M.R. House and J.R. Senior, eds. Systematics Assoc. Pub Academic Press.
Haploceratidae
Ammonitida families Haploceratoidea Kimmeridgian first appearances Early Cretaceous extinctions {{Ammonitina-stub