Conlinoceras

Conlinoceras, once included with Calycoceras as the subgenus Calycoceras (Conlinocras), is a strongly ribbed, evolute ammonite, belonging to the acanthoceratid subfamily Acanthoceratinae, known from the Cenomanian 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.

Conlinoceras Temporal range: Late Cretaceous (Cenomanian)
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	†Ammonoidea
Order:	†Ammonitida
Family:	†Acanthoceratidae
Subfamily:	†Acanthoceratinae
Genus:	†Conlinoceras Cobban & Scott, 1972
Species
See text

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.