Annuloceras

{{Short description|Genus of molluscs (fossil)}}

{{Italic title}}

{{Taxobox

|image = Annuloceras_summersi.JPG

|image_caption = Annuloceras summersi

|fossil_range = {{fossil range|Barremian|ref={{cite web

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

|regnum = Animalia

|phylum = Mollusca

|classis = Cephalopoda

|ordo = Ammonitida

|subordo = Ancyloceratina

|superfamilia = Protancyloceratoidea

|familia = Aegocrioceratidae

|genus = Annuloceras

|genus_authority = Murphy et al, 1995

|subdivision_ranks = Species

|subdivision =

• A. summersi

}}

Annuloceras ("Ringed Horns") is an extinct genus of ammonite cephalopod. Its fossils are found in Lower Barremian sediments from California. The genus is currently placed in the family Aegocrioceratidae.{{cite journal |last1=Klein |first1=J. |year=2007 |title=Lower Cretaceous Ammonites III Bochianitoidea, Protancyloceratoidea, Ancyloceratoidea, Ptychoceratoidea. |journal= Fossilium Catalogus I: Animalia |volume=144 |pages=1–381 |display-authors=etal}}

Annuloceras is a heteromorph ammonite similar in form to other heteroceratids except that the early helix is more loosely wound. Macroscaphites differs in that the early portion is planispiral and tightly wound. Contemporary Shastoceras, found the same strata in California, differs in lacking a coiled juvenile section.