Turrilitoidea is a diverse superfamily of Cretaceous ammonites generally considered as heteromorphic and commonly included in the suborder

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 ...

. Shells of this diverse group do not coil planospirally, as typical for most

ammonites Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

, but rather take on a variety of unique forms. Separation of Turrilitoidea along with Ptychoceratoidea and Scaphatoidea into a different suborder,

Turrilitina Turrilitina is a proposed suborder of Cretaceous heteromorph ammonoid cephalopods derived from the Lytoceratidae in the Hauterivian stage of the Lower Cretaceous that would include the superfamilies Turrilitoidea, Ptychoceratoidea, and Scapha ...

, was proposed by Beznosov and Mikhailova in 1983 however this view is not accepted by most authors. Some, such as the eponymous ''

Turrilites ''Turrilites'' is a genus of helically coiled ammonoid cephalopods from the lower part of the Upper Cretaceous (Cenomanian and Turonian); generally included in the Ancyloceratina. Previously (Arkell, 1957) it was included in the ammonoid suborder ...

'', coiled helically, like an

auger shell Auger may refer to: Engineering * Wood auger, a drill for making holes in wood (or in the ground) ** Auger bit, a drill bit * Auger conveyor, a device for moving material by means of a rotating helical flighting * Auger (platform), the world's ...

, while others, such as ''

Hamites Hamites is the name formerly used for some Northern and Horn of Africa peoples in the context of a now-outdated model of dividing humanity into different races which was developed originally by Europeans in support of colonialism and slavery. ...

'', had shells with long straight sections, while the one-of-a-kind ''

Nipponites ''Nipponites'' is an extinct genus of heteromorph ammonites. The shells of ''Nipponites'' (primarily ''N. mirabilis'') form "ox-bow" bends, resulting in some of the most bizarre shapes seen among ammonites. The ecology of ''Nipponites'', as wit ...

'' coiled in a way so as to appear as a ball of knots. As with other ammonites, the last of the Turrilitoidea had perished by the end of the Cretaceous during the

Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the ...

References

* Arkell ''et al.'', 1957. Mesozoic Ammonoidea,''in'' Treatise on Invertebrate Paleontology, Part L (Ammonoidea). Ammonitida superfamilies Cretaceous ammonites Aptian first appearances Maastrichtian extinctions {{Ammonitida-stub