Anisoceratidae

Anisoceratidae Temporal range:
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	†Ammonoidea
Order:	†Ammonitida
Suborder:	†Ancyloceratina
Superfamily:	†Turrilitoidea
Family:	†Anisoceratidae Hyatt, 1900
Genera
Algerites Allocrioceras Anisoceras Idiohamites Ndumuiceras Phlycticrioceras Protanisoceras Tarrantites

Anisoceratidae is an extinct family of heteromorph ammonites which belong to the Ancyloceratina superfamily Turrilitoidea. Members of the family range is from the lower Albian to the upper Turonian. The family is possibly derived from a member of the Hamitidae.

Morphology

Anisoceratid shells begin as an irregular helical spiral which typically becomes confined to a single plane with growth. This is usually followed by at least a single straight shaft. Ribs and tubercles are common features.

History and classification

Older classifications, since first publication of Part L of the Treatise on Invertebrate Paleontology, include the Anisoceratidae in the suborder Ancyloceratina (within the Turrilitoidea). Subsequent study, e.g. Beznosov & Mikhailova 1983, has suggested that the Turrilitoidea, including the Anisoceratidae, have a different phylogeny from the true Ancyloceratina, resulting in their occasional reassignment to a separate suborder, the Turrilitina, however this classification is not widely followed.

References

• Arkell, W.J.; Kummel, B.; Wright, C.W. (1957). Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Lawrence, Kansas: Geological Society of America and University of Kansas Press.
• Beznosov & Mikhailova 1983 referenced in A. Mikhailova and E. Yu. Baraboshkin, 2009. The Evolution of the Heteromorph and Monomorph Early Cretaceous Ammonites of the Suborder Ancyloceratina Wiedmann. Paleontological Journal, Vol. 43, No. 5, 2009.
• The Paleobiology Database Anisoceratidae entry