{{Short description|Genus of molluscs (fossil)}} {{Automatic taxobox | fossil_range = {{Fossilrange|182.7|181.0|ref=<ref name=Howarth2013>M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea.</ref>|Early Toarcian to Middle Toarcian}} | image = Posidonienschiefer Holzmaden - d.jpg | image_caption = ''Harpoceras falcifer'' from Posidonia Shale, Germany | taxon = Harpoceras | authority = Waagen, 1869 | type_species = ''Ammonites falcifer'' | type_species_authority = Sowerby, 1820 | subdivision_ranks = Species | subdivision_ref = <ref name="paleodb"/> | subdivision = * ''Harpoceras falciferum'' <small>Sowerby, 1820</small> * ''Harpoceras kisslingi'' <small>Hug, 1898</small> * ''Harpoceras lassum'' <small>Buckman, 1927</small> * ''Harpoceras mediterraneum'' <small>Pinna, 1968</small> * ''Harpoceras pseudoserpentinum'' <small>Gabilly, 1973</small> * ''Harpoceras rulleaui'' <small>Bécaud, 2006</small> * ''Harpoceras serpentinum'' <small>Schlotheim, 1813</small> * ''Harpoceras strangewaysi'' <small>Sowerby, 1820</small> * ''Harpoceras subexaratum'' <small>Bonarelli, 1899</small> * ''Harpoceras subplanatum'' <small>Oppel, 1856</small> * ''Harpoceras loeve'' <small>Gabilly, 1975</small> | synonyms = * ''Falcifericeras'' <small>Breistroffer, 1949</small> * ''Gallitellia'' <small>Venturi and Ferri, 2001</small> * ''Glyptarpites'' <small>Buckman, 1927</small> * ''Harpoceratoides'' <small>Buckman, 1909</small> * ''Kolymoceras'' <small>Dagis, 1970</small> * ''Lioceras'' <small>Bayle, 1878</small> * ''Maconiceras'' <small>Buckman, 1926</small> * ''Phaularpites'' <small>Buckman, 1928</small> * ''Tardarpoceras'' <small>Buckman, 1927</small> }}
'''''Harpoceras''''' is an extinct genus of ammonite belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during the Toarcian age from the Falciferum zone to the Commune subzone of the Bifrons zone.<ref name=fb>Sepkoski, Jack [http://strata.geology.wisc.edu/jack/showgenera.php?taxon=231&rank=class Sepkoski's Online Genus Database – Cephalopoda]</ref> They were fast-moving nektonic carnivores.<ref name="paleodb">[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=14967 Paleobiology Database - Harpoceras]. 2017-10-16.</ref>
thumb|180px|left|Artist's impression of ''Harpoceras''
==Description== Shells of ''Harpoceras'' species show strong dimorphism in their size. While microconchs reach 24–51 mm in diameter, macroconchs shells width is 115–430 mm. They are moderately evolute to involute and compressed. Whorl sides are flat and there is strong keel. Ribs are falcoid or falcate and thus biconcave, strong and projected. Sometimes, ribs can be broad and flat topped on outer part of whorl and in some species they can be striate on inner part of whorl. Some species have midlateral groove, or series of undulating depressions on inner half of whorl.<ref name=Howarth2013/><ref name="paleodb"/>
==Distribution== Fossils of species within this genus have been found in the Lower Jurassic rocks of Europe, Northern Africa, Russia, Japan, Borneo, New Zealand, Indonesia, North and South America (Argentina; El Cholo and Los Molles Formations).<ref name=Howarth2013/> Two species, ''Harpoceras serpentinum'' and ''Harpoceras falciferum'', are index fossils used for stratigraphic correlation and dating of rocks of the Toarcian stage of the Lower Jurassic.<ref name="Gradstein_et-al_2012">{{cite book |chapter=Jurassic|title=The Geologic Timescale 2012 | publisher=Elsevier|author1=Ogg, J.G.|author2=Hinnov, L.A.|author3=Huang, C. |editor1=Gradstein, F.M.|editor2=Ogg, J.G.|editor3= Schmitz, M.D.|editor4= Ogg, G.M.| year=2012 | page=766 | isbn=978-0-44-459390-0|chapter-url=https://www.sciencedirect.com/science/article/abs/pii/B9780444594259000263}}</ref>
==References== {{Reflist}}
{{Taxonbar|from=Q3783467}}
Category:Hildoceratidae Category:Ammonitida genera Category:Toarcian life Category:Early Jurassic ammonites of Europe Category:Jurassic Germany Category:Fossils of Germany Category:Posidonia Shale Category:Early Jurassic ammonites of North America Category:Early Jurassic ammonites of South America Category:Jurassic Argentina Category:Fossils of Argentina Category:Neuquén Basin Category:Early Jurassic ammonites of Asia Category:Early Jurassic ammonites of Africa Category:Fossil taxa described in 1869
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