Systematic Paleontology Class: Cephalopoda Subclass: Ammonoidea Order: Ammonitida Family: Acanthoceratidae Subfamily: Acanthoceratinae Genus: Romaniceras Romaniceras is an acanthoceratid ammonite similar to Acanthoceras. Its shell is also evolute and strongly ribbed, but with a different pattern to the tubercles. Fossils of Romaniceras have been found in upper Cenomanian to upper Turonian age (Upper Cretaceous) marine sediments.