''Creniceras'' is a rather small Upper Jurassic

ammonite 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) ...

with a shell in the range of about 1.6 cm in diameter,(about 1/2 in). The shell of ''Creniceras'' is eccentrically coiled, compressed, and generally smooth, except for a median row of cockscomb serrations on the body chamber and the possibility of blunt ribbing on the sides. ''Creniceras'', named by Munier-Chalmas in 1892, is included in the oppeliid subfamily Teramelliceratinae, and has been found in Upper Jurassic (Oxfordian age) sediments in Europe and Syria.

References

Arkell ''et al'', 1957. Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology Part L. Geological Society of America and Univ. Kansas Press. p. L282. {{Taxonbar, from=Q5184155 Jurassic ammonites Ammonites of Europe Oxfordian life Oppeliidae Ammonitida genera