''Conlinoceras'', once included with ''

Calycoceras ''Calycoceras'' is an extinct genus of cephalopods belonging to the subclass Ammonoidea and family Acanthoceratidae that lived during the Cenomanian stage of the Late Cretaceous, 100-94 Mya. Their shells had ornate ribs. Species *''C. algeriens ...

'' as the subgenus ''Calycoceras (Conlinocras)'', is a strongly ribbed, evolute ammonite, belonging to the acanthoceratid subfamily

Acanthoceratinae The Acanthoceratinae comprise a subfamily of ammonoid cephalopods that lived during the Late Cretaceous from the latter early Cenomanian to the late Turonian Shells are evolute, tuberculate and ribbed, with subquadrate to squarish whorl sectio ...

, known from the

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 ...

stage of the Upper Cretaceous. Shells are generally rapidly expanding with prominent, wide spaced, straight radial ribs that cross over the arched venter without interruption. Although somewhat similar in appearance to ''Calycoceras'', ''Conlinoceras'' differs in having sparser, more widely spaced ribs. The first (lowest) appearance of ''Conlinoceras tarrantense'', which can reach a diameter of 12.5 cm ( 4.9 in), marks the base of the middle Cenomanian in Texas.

References

* ''Conlinoceras'' i
Acanthoceratinae
i

jsdammonite

Ammonites of North America Acanthoceratidae Ammonitida genera Cenomanian life {{ammonitina-stub