Harpoceras

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Harpoceras
Temporal range: Early Toarcian to Middle Toarcian [1]
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Hildoceratidae - Harpoceras subplanatum.JPG
Fossil shell of Harpoceras subplanatum from Isère (France), on display at Galerie de paléontologie et d'anatomie comparée in Paris
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass:† Ammonoidea
Order:† Ammonitida
Family:† Hildoceratidae
Subfamily:† Harpoceratinae
Genus:† Harpoceras
Waagen 1869
Type species
Ammonites falcifer
Sowerby, 1820
Species [2]
  • Harpoceras falciferumSowerby, 1820
  • Harpoceras kisslingiHug, 1898
  • Harpoceras lassumBuckman, 1927
  • Harpoceras mediterraneumPinna, 1968
  • Harpoceras pseudoserpentinumGabilly, 1973
  • Harpoceras rulleauiBécaud, 2006
  • Harpoceras serpentinumSchlotheim, 1813
  • Harpoceras strangewaysiSowerby, 1820
  • Harpoceras subexaratumBonarelli, 1899
  • Harpoceras subplanatumOppel, 1856
  • Harpoceras loeveGabilly, 1975
Synonyms
  • FalcifericerasBreistroffer, 1949
  • GallitelliaVenturi and Ferri, 2001
  • GlyptarpitesBuckman, 1927
  • HarpoceratoidesBuckman, 1909
  • KolymocerasDagis, 1970
  • LiocerasBayle, 1878
  • MaconicerasBuckman, 1926
  • PhaularpitesBuckman, 1928
  • TardarpocerasBuckman, 1927

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. [3] They were fast-moving nektonic carnivores. [2]

Contents

Artist's impression of Harpoceras Harpoceras NT.jpg
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. [1] [2]

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). [1] 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. [4]

Related Research Articles

<i>Dactylioceras</i> Genus of molluscs (fossil)

Dactylioceras was a widespread genus of ammonites from the Lower Jurassic period, approximately 180 million years ago (mya).

The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 184.2 Ma and 174.7 ±0.8 Ma. It follows the Pliensbachian and is followed by the Aalenian.

<span class="mw-page-title-main">Aalenian</span> First age of the Middle Jurassic

The Aalenian is a subdivision of the Middle Jurassic Epoch/Series of the geologic timescale that extends from about 174.7 ±0.8 Ma to about 170.9 ±0.8 Ma. It was preceded by the Toarcian and succeeded by the Bajocian.

<i>Stephanoceras</i> Genus of molluscs (fossil)

Stephanoceras is an extinct genus of Stephanoceratoid ammonite which lived during the Bajocian. It is the type genus of the family Stephanoceratidae.

<i>Echioceras</i> Genus of molluscs (fossil)

Echioceras is an extinct genus of ammonites from the Early Jurassic of Europe and North America.

<i>Normannites</i>

Normannites is a strongly ribbed evolute Middle Jurassic genus of ammonite included in the stephanoceratoid family Stephanoceratidae.

<i>Peltoceras</i> Genus of molluscs (fossil)

Peltoceras is an extinct ammonite genus from the aspidoceratid subfamily Peltoceratinae that lived during the later part of the Middle Jurassic.

<i>Lobolytoceras</i> Genus of molluscs (fossil)

Lobolytoceras is an extinct genus of ammonite in which only the inner whorls have large swollen ribs, later whorls have wrinkled growth lines which coarsen somewhat, near the aperture. The genus is known from the Lower Jurassic Toarcian of Europe. The type species L. siemensi (Denck) came from the Upper Toarcian of Germany.

<i>Hammatoceras</i> Genus of molluscs (fossil)

Hammatoceras is a genus of ammonites belonging to the family Hammatoceratidae which lived during the Toarcian stage of the Early/Lower Jurassic between about 184 and 175 million year ago.

Ovaticeras is an extinct genus of cephalopod belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during upper Pliensbachian and lower Toarcian. Its fossils were found in Europe, North Africa and possibly also in Canada and Vietnam. It might have evolved from Harpoceras falciferum and died out without leaving any descendants.

<i>Osperleioceras</i> Genus of molluscs (fossil)

Osperleioceras is an extinct genus of cephalopod belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during Toarcian stage. Its fossils were found in Europe and South America. First species of this genus, Osperleioceras bicarinatum has evolved in what is now France from Harpoceras subplanatum.

<i>Cleviceras</i> Genus of molluscs (fossil)

Cleviceras is an extinct genus of cephalopod belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during Toarcian and possibly even uppermost Pliensbachian age. Sometimes, it is considered to be a synonym of Eleganticeras.

Radstockiceras is an extinct genus of lower Jurassic ammonite that lived from Oxynotum zone of upper Sinemurian to Raricostatum zone of lower Pliensbachian. Shells of these animals were oxycone and involute with umbilicus that took maximum of 12% of diameter in the case of outer whorls. On inner whorls, venter has been sharp, but then it became rounded. Faint ribs had falcoid shape, but sometimes, ribs could absent. Shells could have been large in their size. Suture has been very complex, similar to Oxynoticeras, but culmination at umbilical margin has been missing. Genus has been named after town of Radstock, in Somerset.

Reynesocoeloceras is genus of ammonite that lived during the lower Pliensbachian stage of early Jurassic, ammonite zones Ibex—Davoei.

Peronoceras is genus of ammonite that lived during the middle Toarcian stage of early Jurassic. Members of this genus existed only in Fibulatum Subzone of Bifrons Zone. Their fossils were found in Europe, northern Africa, Asia, North America and South America.

Porpoceras is genus of ammonite that lived during the early and middle Toarcian stage of early Jurassic. Members of this genus existed from uppermost part of the Harpoceras serpentinum zone to the Haugia variabilis zone. Their fossils were found in Europe, Asia, North America and South America.

Reynesoceras is genus of ammonites that lived during the upper Pliensbachian stage of early Jurassic. It has evolved from Prodactylioceras, or Cetonoceras. Dactylioceras (Eodactylites) has probably evolved from this genus. Aveyroniceras is a name for macroconchs of this genus. Their fossils were found in Europe, northern Africa, Asia, North America and South America.

<i>Catacoeloceras</i> Extinct genus of ammonites

Catacoeloceras is a genus of ammonite that lived during Middle Toarcian stage of early Jurassic. Members of this genus existed from Bifrons Subzone of Bifrons Zone to Variabilis Zone. Their fossils were found in Europe, northern Africa, Asia, North America and South America. It has evolved from Porpoceras.

Nodicoeloceras is genus of ammonite that lived during early to middle Toarcian stage of early Jurassic. Members of this genus existed from Exaratum Subzone of Falciferum Zone to Commune subzone of Bifrons Zone. Their fossils were found in Europe, northern Africa, Asia, North America and South America. It has probably evolved from Dactylioceras (Orthodactylites) or Kedonoceras and gave rise to Mesodactylites.

<i>Orthildaites</i> Genus of molluscs (fossil)

Orthildaites is a genus of ammonites that lived during the lower Toarcian stage of early Jurassic, during Falciferum subzone.

References

  1. 1 2 3 M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea.
  2. 1 2 3 Paleobiology Database - Harpoceras. 2017-10-16.
  3. ↑ Sepkoski, Jack Sepkoski's Online Genus Database – Cephalopoda
  4. ↑ Ogg, J.G.; Hinnov, L.A.; Huang, C. (2012). "Jurassic". In Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M. (eds.). The Geologic Timescale 2012. Elsevier. p. 766. ISBN   978-0-44-459390-0.


Acanthoceras rhotomagense 1.JPG

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