Phylloceratidae
Encyclopedia
Phylloceratidae is the predominant family of the Phylloceratina
with some 15 or more genera found in rocks ranging from the Lower Jurassic
to the Upper Cretaceous
. 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.
by increasing the sutural complexity and evolving involute coiling. The Discophyllitidae in tern 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
, the early Lower Jurassic Peluroacanthitidae and Ectocentridae. The Phyloceratidae also gave rise at or near the beginning of the Jurassic to the Psilocerataceae which unites families of the Early Jurassic Ammonitina
. Other Jurassic Ammonitina are derived from the Lytoceratina. Later, phylloceratids are said to have given rise to Cretaceous Ammonitina included in the Desmocerataceae, Hoplitaceae, and Acanthocerataceae.
Phylloceratina
The Phyllocertina comprise a suborder of ammonoid cephalopods, belonging to the Ammonitida, whose range extends from the Lower Triassic to the Upper Cretaceous...
with some 15 or more genera found in rocks ranging from the Lower Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
to the Upper Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. 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.
Evolution and phylogeny
The Phylloceratidae are probably derived from the Late Triassic DiscophyllitidaeDiscophyllitidae
Discophyllitidae are discoidal, generally evolute Phylloceratina from the Upper Triassic, derived from the Ussuritidae, in which the principal saddles of the suture have bifurcated or trifurcated endings, described as being di- or triphyllic. Discophyllitid shells are rather similar to those of...
by increasing the sutural complexity and evolving involute coiling. The Discophyllitidae in tern have their origin in the Ussuritidae
Ussuritidae
Ussuritidae are ancestral, Triassic, Phylloceratina characterized by generally smooth, discoidal, evolute shells with rounded venters and little or no ornamentation and by sutures with primitive monophyllitic saddles with a single terminal branch or leaflet....
, also known as the Monophyllitidae.
The Phylloceratidae gave rise at or near the beginning of the Jurassic to the ancestral Lytoceratina
Lytoceratina
Lytoceratina is a suborder of Jurassic and Cretaceous ammonites that produced loosely coiled, evolute and gyroconic shells in which the sutural element are said to have complex moss-like endings.-Morphologic characteristics:...
, the early Lower Jurassic Peluroacanthitidae and Ectocentridae. The Phyloceratidae also gave rise at or near the beginning of the Jurassic to the Psilocerataceae which unites families of the Early Jurassic Ammonitina
Ammonitina
The Ammonitina comprises a diverse suborder of ammonoid 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 to specific geological time periods.The shells of...
. Other Jurassic Ammonitina are derived from the Lytoceratina. Later, phylloceratids are said to have given rise to Cretaceous Ammonitina included in the Desmocerataceae, Hoplitaceae, and Acanthocerataceae.
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
- PhyllocerasPhyllocerasPhylloceras is an extinct genus of ammonite....
Suess, 1865 - Phyllopachyceras Spath, 1925
- ZetocerasZetocerasZetoceras is an extinct ammonoid cephalopod genus from the suborder Phylloceratina that lived during the Early and Middle Jurassic in what is now Europe, and is included in the Phylloceratidae....
Kovacs, 1939
- incertae sedisIncertae sedis, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
- Bonarellia