''Anasirenites'' is a genus of extinct

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 within the family

Trachyceratidae The Trachyceratidae is an extinct family of ceratitid ammonoid cephalopods. The Trachyceratidae makes up part of the superfamily Trachyceratoidea along with such families as the Buchitidae, Distichitidae, Dronovitidae and Noridiscitidae. ...

which is part of the

ceratitid Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post Triassic ammoni ...

superfamily

Clydonitaceae Clydonitoidea, formerly Clydonitaceae, is a superfamily in the ammonoid cephalopod order Ceratitida characterized by generally costate and turberculate shells with smooth, grooved, or keeled venters and sutures that are commonly ceratitic or ammon ...

; sometimes considered a subgenus of '' Sirenites''. ''Anasirenites'' is characterized by a ventral furrow bordered on either side by a continuous keel. The shell, as for ''Sirenites'', is compressed with whorls flattened-convex on the sides. Sigmoidal ribs on the flanks bifurcate near the ventro-lateral shoulder on tubercles and project sharply adorally. Whorl sides are tuberculate with tubercles arranged in spiral lines. The suture is ammonitic. ''Anasirenites'', first described by Mojsisovics in 1893 is known from the

Upper Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. Th ...

of the Alps, Sicily, and the Himalaya.

References

* Treatise on Invertebrate Paleontology, part L, Ammonoidea; Geological Society of America and the University of Kansas Press. (L-158-159,& rel) Trachyceratidae Triassic ammonites of Europe Ceratitida genera Late Triassic ammonites {{Ceratitida-stub