Acanthoceratoidea, formerly Acanthocerataceae, is a superfamily of Upper Cretaceous

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) ...

cephalopods 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, an ...

belonging to the order

Ammonitida Ammonitida is an order of ammonoid cephalopods that lived from the Jurassic through Paleocene time periods, commonly with intricate ammonitic sutures. Ammonitida is divided into four suborders, the Phylloceratina, Lytoceratina, Ancyloceratina, a ...

, and comprising some 10 or so families.W.J Arkell ''et al''., Mesozoic Ammonoidea; Treatise on Invertebrate Paleontology, Part L, Ammonoidea. 1957

Diagnosis

Members of the Acanthoceratoidea are typically strongly ribbed and have a tendency to develop prominent tubercles, although other types including those with oxyconic shells are included.

Taxonomy

Families included in the Acanthoceratoidea are: *

Acanthoceratidae Acanthoceratidae is an extinct family of acanthoceratoid cephalopods in the order Ammonitida, known from the Upper Cretaceous. The type genus is '' Acanthoceras''. Diagnosis Acanthoceratidae species are strongly tuberculate with at least umbil ...

Brancoceratidae Brancoceratidae is a family of acanthoceratoid ammonites from the middle of the Cretaceous, recognized by their commonly evolute shells with round, oval, or quadrate whorls, strong ribs, usual ventral keels, and at least, umblical tubercles. Th ...

* Coilopoceratidae *

Collignoniceratidae Collignoniceratidae is a family of Upper Cretaceous ammonites characterized by typically more or less evolute shells with compressed, oval, or square whorl sections; serrate or entire keels; and dense ribs with one to 5 tubercles. Taxonomy This ...

Flickiidae Flickiidae is a family of dwarf ammonites with little ornament and very simples sutures known from small pyritic specimens found in middle Cretaceous deposits. Inclusion in the Acanthoceratoidea is tentative. Taxonomy Flickiidae has been divided ...

Lyelliceratidae Lyelliceratidae is a family of ammonites belonging to the superfamily Acanthoceratoidea Acanthoceratoidea, formerly Acanthocerataceae, is a superfamily of Upper Cretaceous ammonoid cephalopods belonging to the order Ammonitida, and comprising ...

* Sphenodiscidae *

Tissotiidae Tissotiidae is a family of ammonites (Ammonitina) belonging to the Acanthoceratoidea. The Tissotiidae are derived from the Vascoceratidae, another acanthoceratoid family, and gave rise to the Coilopoceratidae. They have been divided into two su ...

Vascoceratidae The Vascoceratidae is a family of Upper Cretaceous ammonites in the superfamily Acanthoceratoidea characterized by shells that are either smooth or bluntly tuberculate, or have sparse, coarse ribs. Sutural elements are shallow, irregular, and sli ...

Discussion

According to Wright Calloman and Howarth, 1996 in the revised version of Part L of the Treatise, the Binneyitidae is replaced by the Forbesiceratidae with the Binneyitidae now in the Hoplitaceae and the Forbesiceratidae included in the Acanthoceratoidea. The

Leymeriellidae Leymeriellidae is a family of Lower Cretaceous ammonites comprising rather small forms distinguished from Hoplitidae by their flattened and grooved ribs and virtual absence of umbilical tubercles. The family is derived from the Desmoceratidae. '' ...

, based on the Lower Albian genus, Leymeriella, was added, extending the range downward. The name Tissotiidae was replaced by Pseudotissotiidae. The Libycoceratidae, proposed by Zaborski, 1982, for the Upper Campanian - Maastrictian Libycoceras, was split off from the Sphenodiscidae. while the other families remain essentially the same, except for the addition of newer genera. The replacement of the Tissotiidae by the Pseudotissotiidae in the revised classification of the Acanthoceraticeae in the Treatise (1996) is based on the earlier appearance of the subfamily Psudotissotiinae in the Lower Turonian, followed by the Tissotiinae in the Upper Turonian. Other newer classifications e.g.TABLE DR1.JURASSIC-CRETACEOUS AMMONOIDEA
/ref> split the Tissotiidae into two families, the earlier Pseudotissotiidae and the later, revised but smaller, Tissotiidae. Fatmi and Kennedy, 1999, returned Libycoceras, sole genus of the Libycoceratidae, to its original position in the Sphenodicidae, so negating the Libycoceratidae.

References

*Fatmi, A N, Kennedy, W J, 1999. Maastrichtian ammonites from Balochistan, Pakistan; Journal of Paleontology, July 1999 *Zaborski, P. M. P. 1982. Campanian and Maastrichtian sphenodiscid ammonites from southern Nigeria. Bull. Br. Mus. nat. Hist. (Geol.) 36(4):303-332 {{Taxonbar, from=Q4671897 Ammonitida superfamilies Ammonitina Late Cretaceous first appearances Late Cretaceous extinctions