Phylloceratidae is the predominant family of the

Phylloceratina The Phyllocertina comprise a suborder of ammonoid cephalopods, belonging to the Ammonitida, whose range extends from the Lower Triassic to the Upper Cretaceous. Shells of the Phylloceratina are generally smooth with small to large umbilici and c ...

with some 15 or more genera found in rocks ranging from the Lower

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

to the Upper

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

. Members of the Phylloceratidae are characterized by smooth, involute shells with very thin walls. Many are covered with fine growth lines but are usually without ribbing. Sutures are complex with the major and minor branches of the saddles with phylloid or spatulate endings.

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

Part L Mollusca 4, Ammonoidea, 1957

Evolution and phylogeny

The Phylloceratidae are probably derived from the Late Triassic Discophyllitidae by increasing the sutural complexity and evolving involute coiling. The Discophyllitidae in turn have their origin in the Ussuritidae, also known as the Monophyllitidae. The Phylloceratidae gave rise at or near the beginning of the Jurassic to the ancestral

Lytoceratina Lytoceratina is a Suborder (biology), suborder of Jurassic and Cretaceous Ammonitida, ammonites that produced loosely coiled, evolute and gyroconic shells in which the sutural element are said to have complex moss-like endings. Morphologic chara ...

, the early Lower Jurassic Peluroacanthitidae and Ectocentridae. The Phyloceratidae also gave rise at or near the beginning of the Jurassic to the

Psiloceratoidea Psiloceratoidea is a superfamily of Early Jurassic ammonoid cephalopods proposed by Hyatt in 1867, assigned to the order Ammonitida. They were very successful during Hettangian and Sinemurian. Last of them, family Cymbitidae and genera '' Hypox ...

which unites families of the Early Jurassic

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 ...

. Other Jurassic Ammonitina are derived from the Lytoceratina. Later, phylloceratids are said to have given rise to Cretaceous Ammonitina included in the Desmoceratoidea, Hoplitoidea, and

Acanthoceratoidea Acanthoceratoidea, formerly Acanthocerataceae, is a superfamily of Upper Cretaceous ammonoid cephalopods belonging to the order Ammonitida, and comprising some 10 or so families.W.J Arkell ''et al''., Mesozoic Ammonoidea; Treatise on Invertebrate ...

Sutural morphology

Sutures in the Phylloceratidae vary in complexity and are usually described on the basis of the saddles, which diverge to the front. Saddle endings may be double (diphyllic), triple (triphyllic), or quadruple (tetraphillic). Branching may be asymmetric. Intervening lobes are variably branched with thorn-like or spinose terminations as viewed in plan.

Subfamilies and genera

* Calliphylloceratinae Spath, 1927 **'' Calliphylloceras'' Spath, 1927 **'' Holcophylloceras'' Spath, 1927 **'' Ptychophylloceras'' Spath, 1927 **'' Sowerbyceras'' Parona & Bonarelli, 1895 * Phylloceratinae Zittel, 1884 **'' Calaiceras'' **'' Carinophylloceras'' Klinger et al., 1975 **'' Hantkeniceras'' **'' Hypophylloceras'' (Salfeld, 1924) **'' Partschiceras'' Fucini, 1920 **'' Phylloceras'' Suess, 1865 **'' Phyllopachyceras'' Spath, 1925 **'' Zetoceras'' Kovacs, 1939 *''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

'' **'' Bonarellia''

References

{{Taxonbar, from=Q7188670 Ammonitida families Early Jurassic first appearances Late Cretaceous extinctions