The Phyllocertina comprise a suborder of ammonoid cephalopods, belonging to the

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, Ancyloceratin ...

, whose range extends from the Lower

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

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 ...

. Shells of the Phylloceratina are generally smooth with small to large umbilici and complex sutures with leaf-like phylloid saddle endings and lobes with thorn-like projections.

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

Phylogeny

The Phylloceratina are most likely derived from the Ceratitid Deineroceratidae, which is thought to have given rise early in the Triassic to the Ussuritidae. The Ussuritidae is the ancestral family of the Phylloceratina. The Ussuritidae extend through the Upper Triassic but not into the Jurassic, and gave rise to the Upper Triassic Discophyllitidae. The Discophyllitidae is the probable source for the L Jurassic - U Cretaceous Phylloceratidae and possibly for the L Jurassic Juraphyllitidae. The Phylloceratina gave rise early in the Jurassic through the Phylloceratidae to the Lytoceratina, which in turn gave rise to most of the Ammonitina The Phylloceratidae also gave rise 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 ...

at the beginning of the Jurassic and to the Desmoceratoidea in the Early Cretaceous, both of which are considered Ammonitina. The Ancyloceratina is a collection of highly evolved Lytoceratina.

References

Ammonitida suborders Early Triassic first appearances Late Cretaceous extinctions {{Ammonitida-stub