''Baltoceras'' is a member of the ''

Ellesmerocerida The Ellesmerocerida is an extinct order of primitive cephalopods belonging to the subclass Nautiloidea with a widespread distribution that lived during the Late Cambrian and Ordovician. Morphology The Ellesmerocerida are characterized by shell ...

'', included in the family, ''

Baltoceratidae Baltoceratidae is an extinct family of orthoconic cephalopods belonging to the subclass Nautiloidea endemic to what would be Asia, Australia, Europe, North America, and South America during the Ordovician living from about 480–460 mya, exist ...

''. The shell of ''Baltoceras'' is slender with a subcircular cross section, straight transverse sutures, and a large

siphuncle The siphuncle is a strand of biological tissue, tissue passing longitudinally through the mollusc shell, shell of a cephalopod mollusc. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the li ...

in contact with the

venter Venter or Venters is an Afrikaans (and rarely, Jewish) surname, and may refer to: Venter * AJ Venter (b. 1973), South African rugby union footballer * Al J Venter (b. 1938), author * André Venter (b. 1970), South African rugby union footballer * ...

. Septal necks are short but not vestigial; connecting rings are thick; endosiphonal organic deposits are unknown. ''Baltoceras'' ranges in age from Whiterock to Chazy (Middle

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

). The few species known are from the upper

Pogonip Limestone Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Reprint from Fog can be considered a type of low-lying cloud usually resembling stratus and is heavily influenced ...

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

, the Day Point

Limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

of New York, and the “Orthoceras limestone” of the

Baltic Baltic may refer to: Peoples and languages *Baltic languages, a subfamily of Indo-European languages, including Lithuanian, Latvian and extinct Old Prussian *Balts (or Baltic peoples), ethnic groups speaking the Baltic languages and/or originatin ...

region of Europe. ''Baltoceras'' differs from ''

Rioceras ''Rioceras'' is an extinct genus of Orthocerida, orthocerid cephalopods of the family Baltoceratidae that lived in what would be North America during the Early Ordovician from 480—472 Annum, mya, existing for approximately 8 million years.R. H. ...

'' in the same family in that ''Baltoceras'' has deeper camerae, longer septal necks and thinner connecting rings. Also ''Rioceras'' is earlier, mostly late

Canadian Canadians () are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''C ...

in age. It should not be confused with the

orthocerid Orthocerida, from Ancient Greek ὀρθός (''orthós''), meaning "straight", and κέρας (''kéras''), meaning "horn", also known as the Michelinocerida, is an order of extinct orthoceratoid cephalopods that lived from the Early Ordovician ...

, ''Balticoceras''.

References

* Flower, R.H. 1964, The Nautiloid Order Ellesmeroceratida (Cephalopoda) Memoir 12; New Mexico Bureau of Mines and Mineral Resources, Socorro, NM *Furnish W.M and Glenister, Brian F 1964, Ellesmerocerida in the

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 ...

pp K129-K157, section on Baltoceratidae, K154-156. {{Taxonbar, from=Q4853001 Ellesmerocerida Ordovician cephalopods Ordovician cephalopods of Europe Middle Ordovician first appearances Late Ordovician extinctions