Hildoceras is a genus of ammonite from the Jurassic[1] period in the family Hildoceratidae. The shells are characterized by a narrow discoidal evolute shape, keeled venter, concave ribs along the outer flanks, and a shallow spiral groove running along smooth inner flanks. Whorls slightly overlap, cross sections are compressed. The ventral keel is bordered on either side by a shallow groove. The genus was named by Alpheus Hyatt after Saint Hilda in 1876.
Distribution
Jurassic of Bulgaria, France, Germany, Hungary, Italy, Japan, Luxembourg, Serbia and Montenegro, Spain, the United Kingdom and Iran.[2][3]
^Seyed-Emami, Kazem, et al. "Toarcian and Aalenian (Jurassic) ammonites from the Shemshak Formation of the Jajarm area (eastern Alborz, Iran)." Paläontologische Zeitschrift 79.3 (2005): 349-369.
Bibliography
Arkell, W.J.; Kummel, B.; Wright, C.W. (1957). Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Lawrence, Kansas: Geological Society of America and University of Kansas Press.