Turrilitina is a proposed suborder of

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

heteromorph

ammonoid Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

cephalopods derived from the Lytoceratidae in the

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.6 ± 2 Ma and 125.77 (million years ago). The Hauterivian is preceded by the Valangi ...

stage of the Lower Cretaceous that would include the superfamilies

Turrilitoidea Turrilitoidea is a diverse superfamily of Cretaceous ammonites generally considered as heteromorphic and commonly included in the suborder Ancyloceratina. Shells of this diverse group do not coil planospirally, as typical for most ammonitida, am ...

, Ptychoceratoidea, and Scaphatoidea. Turrilitina was recognized as a distinct group or clade from the

Ancyloceratina The Ancyloceratina were a diverse suborder of ammonite most closely related to the ammonites of order Lytoceratina. They evolved during the Late Jurassic but were not very common until the Cretaceous period, when they rapidly diversified and beca ...

as defined by Weidmann, 1966, by Beznosov and Mikhailova in 1983. The group may have its origin in the ammonitid superfamily Perisphinctaceae. Turrilitina is the Turrilitaceae of Arkell ''et al'' 1957, including the Ptychoceratidae and Macroscaphitidae, along with the Scaphitaceae which the

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

shows with a separate and later derivation from the Lytoceratidae. Acceptance of Turrilitina as a valid suborder is not widely held, with most authors preferring the placement of Turriloidea, Ptychoceratoidea, and Scaphatoidea in Ancyloceratina.

References

* Arkell ''et al'' 1957. Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology, Part L (Ammonoidea). Geol. Soc. Amer. and Univ. Kans. press. * Beznosov & Mikhailova,1983, in Mikhailova, I.A. and E. Yu. Baraboshkin, 2009. The Evolution of the Heteromorph and Monomorph Early Cretaceous Ammonites of the Suborder Ancyloceratina Wiedmann, Paleontological Journal, 2009, Vol. 43, No. 5, pp. 527–536. Ammonitida Mollusc suborders {{ammonitida-stub