''Turrilites (Turrilites) costatus'' is a species 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) ...
cephalopod, 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 ...
).
Description
The shell of this species can reach a length of about . It is tightly wound in a high trochospiral, with an acute angle at the apex. Ribs are weak, with rows of strong tubercles.
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=Q16993268
Cretaceous ammonites
Turrilitoidea
Cenomanian life