Zetoceras
Encyclopedia
Zetoceras 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 (family) Phylloceratidae
.
Zetoceras has a compressed involute shell with a very small umbilicus. The suture is phylloid, as for the suborder,with tall primary sutural elemnts. Saddles commonly have tetraphyllic endings. Zetoceras is considered by some (Wright et al 1996) to be a sugenus of Phylloceras
. The two are very similar except that the saddle endings in Phylloceras
split in three rather than in four as in Zetoceras.
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
from the suborder Phylloceratina
Phylloceratina
The Phyllocertina comprise a suborder of ammonoid cephalopods, belonging to the Ammonitida, whose range extends from the Lower Triassic to the Upper Cretaceous...
that lived during the Early and Middle 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...
in what is now Europe, and is included in the (family) Phylloceratidae
Phylloceratidae
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...
.
Zetoceras has a compressed involute shell with a very small umbilicus. The suture is phylloid, as for the suborder,with tall primary sutural elemnts. Saddles commonly have tetraphyllic endings. Zetoceras is considered by some (Wright et al 1996) to be a sugenus of Phylloceras
Phylloceras
Phylloceras is an extinct genus of ammonite....
. The two are very similar except that the saddle endings in Phylloceras
Phylloceras
Phylloceras is an extinct genus of ammonite....
split in three rather than in four as in Zetoceras.