Systematic Paleontology Order: Ammonitida Family: Acanthoceratidae Genus: Mantelliceras Mantelliceras is a strongly ribbed, subinvolute ammonitid from the lower Cenomanian stage of the Upper Cretaceous included in the Acanthoceratidae. The venter is typically flat with a row of tubercles on either side. Ribs either pass over the venter or are interrupted. In addition there are usually distinct umbilical tubercles and one or two rows of lateral tubercles on the flanks. Mantelliceras gave rise to Calycoceras. Graysonites, Sharpeiceras, and Utaturiceras are among those given as closely related.