''Ammonoceratites'' is an extinct genus of

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) ...

cephalopod 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 ...

known from the

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 M ...

(upper Lower Cretaceous) of British Columbia, Madagascar, New Zealand, and Japan, included in the

Lytoceratidae Lytoceratidae is a taxonomic family of ammonoid cephalopods belonging to the suborder Lytoceratina, characterized by very evolute shells that generally enlarge rapidly, having whorls in contact but mostly overlapping very sightly, or not at all. ...

. The shell of ''Ammonoceratites'' is evolute, smooth, moderately expanded; the inner rim (dorsum) only slightly impressed; whorl section subcircular. It is similar to that of ''

Lytoceras ''Lytoceras'' is an ammonite genus that was extant during most of the Jurassic and Cretaceous periods, and is the type genus for the family Lytoceratidae. These cephalopods were fast-moving nektonic carnivores. Description Shells of ''Lytoceras' ...

'' which has transverse ribbing and to that of ''

Pictetia ''Pictetia'' is a genus of about eight species of trees and shrubs in the legume family with Thorns, spines, and prickles, spiny stems and (in six of the eight species) spine-tipped leaflets.Beyra & Lavin (1999), pp.36–38 The genus is endemism, ...

'' which is gyroconic (whorls not touching) and more strongly expanded.

References

*Arkell ''et al.'', 1957. Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology, Part L; Geological Society of America and University of Kansas press. *C. W. Wright, J. H. Calloman, and M. K. Howarth. 1996. Cretaceous Ammonoidea. Treatise on Invertebrate Paleontology ''revised'' L(4):1-362 * Early Cretaceous ammonites Prehistoric animals of Madagascar Ammonitida genera Lytoceratidae Albian genera Fossils of British Columbia Fossils of New Zealand Fossils of Japan {{ammonitida-stub