Sirenites

Sirenites is a genus of ammonoid cephalopods from the Upper Triassic included in the Ceratitida, and type for the trachyceratid subfamily Sirenitinae.

Sirenites Temporal range: Upper Triassic
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	†Ammonoidea
Order:	†Ceratitida
Family:	†Trachyceratidae
Subfamily:	†Sirenitinae
Genus:	†Sirenites Mojsisovics, 1893

Sirenites has a compressed shell with distinct furrow running along the outer rim. Sides of the whorls are flattened to convex and covered with sigmoidal ribs that split on tubercles near the outer shoulder. there are two rows of tubercles on whorl sides and one on the inner, or umbilicle, shoulder. Although Sirenites is a ceratitid ammonoid, it suture is ammonitic.

References

Arkell, et al., Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology, Part L, Mollusca 4, Geological Society of America. 1957.