''Bassleroceras'' is an elongate upwardly curved, exogastric, genus with the venter on the under side more sharply rounded than the dorsum on the upper. The

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

is ventral, composed of thick-walled tubular segments in which connection rings thicken in towardly as in both the

Ellesmerocerida The Ellesmerocerida is an 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 shells that ...

and primitive

Tarphycerida The Tarphycerida were the first of the coiled cephalopods, found in marine sediments from the Lower Ordovician (middle and upper Canad) to the Middle Devonian. Some, such as '' Aphetoceras'' and '' Estonioceras'', are loosely coiled and gyroconi ...

. ''Bassleroceras'' is the type genus of the

Bassleroceratidae The Bassleroceratidae is a family of gradually expanding, smooth ellesmerocerids with a slight to moderate exogastric curvature, subcircular to strongly compressed cross section, and ventral orthochaonitc siphuncle. The ventral side is typicall ...

which Furnish and Glenister (1964) included in the Ellesmerocerida, but which

Flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

(1967) placed in the Tarphycerida. ''Bassleroceras'' gave rise to the Tarphycerida (sensu Furnish and Glenister, 1964) by evolving genera with tighter and tighter curvatures until becoming gyroconic, a character of the Estonioceratidae, a family of early tarphycerids. ''Bassleroceras'' is found widespread in North America, e.g. New Mexico and New York, and in W. Australia.

''References''

* Flower, Rousseau H. (1976). Ordovician Cephalopod Faunas and Their Role in Correlation, in Bassett, M.C. (Ed); The Ordovician System: Proceedings of a Paleontological Association Symposium; Birmingham, Eng. 1974; Univ of Wales and Welsh Nat'l Mus Press * W. M. Furnish & Glenister, Brian F. 1964. Nautiloidea - Ellesmerocerida Treatise on invertebrate Paleontology, Part K. Teichert and Moore, eds. * W. M. Furnish & Glenister, Brian F. 1964. Nautiloidea - Tarphycerida. ''ibid'' {{Taxonbar, from=Q4868170 Ellesmerocerida Paleozoic life of Newfoundland and Labrador Paleozoic life of Quebec