Hypophylloceras

{{Short description|Extinct genus of ammonites}}

{{Automatic taxobox

| fossil_range = {{fossil range|Valanginian|Maastrichtian|ref={{cite web

| last = Sepkoski| first = Jack| title= Sepkoski's Online Genus Database|authorlink =| year = 2002| url = http://strata.geology.wisc.edu/jack/showgenera.php?taxon=231&rank=class| accessdate = 2014-05-28 }}}}

| image = Hypophylloceras.jpg

| image_caption = An artistic reconstruction of Hypophylloceras

| taxon = Hypophylloceras

| authority = Salfeld, 1924

}}

Hypophylloceras is a Cretaceous ammonite with a finely ribbed, compressed, involute shell; some having periodic stronger ribs or folds. The suture is complex, with large, asymmetric and finely divided lobes; the 1st lateral being much larger than the external (=ventral) and 2nd lateral lobes. Saddle endings commonly not phylloid.{{cite book| first1=W.J. |last1=Arkell |first2=B. |last2=Kummel |first3=C.W. |last3=Wright |series=Treatise on Invertebrate Paleontology, Part L, Mollusca 4| title=Mesozoic Ammonoidea | publisher=Geological Society of America and University of Kansas Press |location=Lawrence, Kansas|year=1957}}

Hypophylloceras includes Neophylloceras Shimizu 1934 (=Paraphylloceras Chimisu 1935 ), Hyporbulites Brestroffer 1947, Goretophylloceras Collingnon 1949 and Aphrotiticeras Mahmoud in Breister, 1952.

The type species Hypophylloceras ononense, named by Salfeld in 1924 and based on Phylloceras ononense Santon 1895, comes from the Aptian of California.