''Arctoceras'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

ceratitid Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post-Triassic ammon ...

ammonoid Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

s from the

Lower Triassic The Early Triassic is the first of three epoch (geology), epochs of the Triassic Period (geology), Period of the geologic timescale. It spans the time between 251.9 annum, Ma and Ma (million years ago). Rocks from this epoch are collectively kno ...

with a moderately narrow discoidal shell and ceratitic suture.Arkell et al 1957, Mesozoic Ammonoidea,

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

Part L, R.C. Moore (ed), p L142 -L145

Appearance

The shell of ''Arctoceras'' is generally involute with compressed whorls that are much higher than wide, flattened sides, narrowly rounded ventral rim, and sutures with wide low saddles and simple serrated lobes.

Classification

''Arctoceras'' was named by

Alpheus Hyatt Alpheus Hyatt (April 5, 1838 – January 15, 1902) was an American zoologist and palaeontologist. Hyatt served as the founding president of the American Society of Naturalists from 1883 to 1884 and was the founding editor of the journal '' T ...

1900 As of March 1 ( O.S. February 17), when the Julian calendar acknowledged a leap day and the Gregorian calendar did not, the Julian calendar fell one day further behind, bringing the difference to 13 days until February 28 ( O.S. February 15 ...

. The genotype ''Arctoceras polaris'' ( Mojsisovics, 1865) was described from the Smithian (

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which ...

) of Spitsbergen (

Svalbard Svalbard ( , ), previously known as Spitsbergen or Spitzbergen, is a Norway, Norwegian archipelago that lies at the convergence of the Arctic Ocean with the Atlantic Ocean. North of continental Europe, mainland Europe, it lies about midway be ...

). Up to seven species were described from the

Vikinghøgda Formation The Vikinghøgda Formation is a geologic formation in Svalbard, Norway. It preserves fossils dating back to the Early Triassic (Griesbachian- Spathian) period. It is split into three members, from oldest to youngest: the Deltadalen Member (Indua ...

of Spitsbergen, though a restudy concluded that only one species, ''Arctoceras blomstrandi'', is valid, with ''A. blomstrandi'' var. ''costatus'' representing a morphologically divergent end member of the lineage. ''Arctoceras'' is the type genus of the Arctoceratidae which is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

in the Meekocerataceae, a superfamily within the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Ceratitida Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post-Triassic ammon ...

. Paleobiology Database -Arctoceras
12/10/09 Ceratitids are ammonoid cephalopods, mostly from the Triassic but with ancestral forms in the

upper Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the sixth and last period o ...

. Meekocerataceae sometimes appears as Meekoceratoidea to conform with a recent ruling of the

ICZN The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its formal author, t ...

regarding superfamily endings.

Occurrence

Apart from Svalbard, ''Arctoceras'' has also been reported from Canada, the United States, Russia, Australia, Afghanistan, and Malaysia.

References

Ceratitida genera Early Triassic ammonites Olenekian life Ammonites of Australia Ammonites of North America Ammonites of Asia {{Ceratitida-stub