''Turrilites'' is a genus of helically coiled

ammonoid 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) ...

cephalopods from the lower part of the Upper Cretaceous (

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

and

Turonian The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by t ...

); generally included in 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 ...

. Previously (Arkell, 1957) it was included in the ammonoid suborder,

Lytoceratina Lytoceratina is a Suborder (biology), suborder of Jurassic and Cretaceous Ammonitida, ammonites that produced loosely coiled, evolute and gyroconic shells in which the sutural element are said to have complex moss-like endings. Morphologic chara ...

. The shell of ''Turrilites'' is tightly wound in a high trochospiral, with an acute angle at the apex. Ribs are weak to strong and may have 3 or 4 rows of equal numbers of tubercles. Thought to be derived from ''

Mariella ''Mariella'' is an ammonoid genus, named by Nowak (1916) from the upper Albian and Cenomanian stages of the mid Cretaceous, included in the Turrilitidae. Its type is ''Turrilites bergeri'' Description ''Mariella'' resembles ''Turrilites'' in ...

''. Includes three subgenera.

Subgenera and species

''Turrilites'' has three subgenera. * ''

Turrilites (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 ...

'' Lamarck, 1801 ** ''Turrilites (Turrilites) acutus'' Passy, 1832 ** '' Turrilites (Turrilites) costatus'' Lamarck, 1801 ** ''Turrilites (Turrilites) scheuchzerianus '' Bosc, 1801 * '' Turrilites (Euturrilites) '' Breistroffer, 1953 * '' Turrilites (Mesoturrilites)'' Subgenus ''Turrilites'' has weak ribs and strong tubercles. Subgenus ''Euturrilites'' has strong ribs, commonly depressed in middle, especially on early whorls, and no tubercles. Subgenus ''Mesoturrilites'' has almost no ribs and clavate tubercles that tend to form spiral ridges.

References

* Arkell ''et al.'', Mesozoic Ammonoidea (L222); Treatise on Invertebrate Paleontology Part L, Ammonoidea. Geological Soc. of America and Univ Kansas Press.
The Paleobiology Database ''Turrilites'' entry
{{Taxonbar, from=Q4000713 Ammonitida genera Prehistoric cephalopod genera Cretaceous ammonites Cenomanian genus first appearances Turonian genus extinctions Ammonites of Africa Ammonites of Asia Ammonites of Australia Cretaceous ammonites of Europe Cretaceous ammonites of North America Ammonites of South America Taxa named by Jean-Baptiste Lamarck Fossil taxa described in 1801 Turrilitoidea