Cassinoceras
Encyclopedia
Cassinoceras is of the nautiloid genus belonging to the endocerid family Piloceratidae
that comes from the late Early Ordovician of eastern North America and adjacent terratories.(Teichert 1964)
Cassinoceras is characterized by short, laterally compressed, rapidly expanding shells in which the upper, dorsal, surface has a convex curvature and diverges strongly from the essentially straight lower, ventral surface. The siphuncle
which entirely fills the apical portion at the back of the shell is also compressed and vertically expanding, and is filled with simple endocones with a complex system of endosiphuncular blades through which a flattened endosiphuncular tube with widely spaced partions runs. (ibid) The shell of Cassinoceras grew to about 25 to 30 cm long.
Cassinoceras was named by Ulrich & Foerste in 1936 for the Fort Cassin Limestone of western Vermont
, from which the upper stage of the Canadian Epoch
, known as the Cassinian gets its name. The genotype is Cassinoceras explanator (Whitfield). A second species Cassinoceras grande Ulrich & Foerste is also known from the Fort Cassin Limestone. The genus has also been found in Newfoundland
, the Arctic islands, and on Spitsbergen
.
Piloceratidae
The Piloceratidae are a compressed, rapidly expanding, cyrtoconic brevicones with holochoanitic ventral siphuncles and simple endocones. Most likely evolved from Clitendoceras, a narrow, slightly endogastric genus intermediate in form between straight shelled Proendoceras and the bulkier...
that comes from the late Early Ordovician of eastern North America and adjacent terratories.(Teichert 1964)
Cassinoceras is characterized by short, laterally compressed, rapidly expanding shells in which the upper, dorsal, surface has a convex curvature and diverges strongly from the essentially straight lower, ventral surface. The siphuncle
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 Spirula...
which entirely fills the apical portion at the back of the shell is also compressed and vertically expanding, and is filled with simple endocones with a complex system of endosiphuncular blades through which a flattened endosiphuncular tube with widely spaced partions runs. (ibid) The shell of Cassinoceras grew to about 25 to 30 cm long.
Cassinoceras was named by Ulrich & Foerste in 1936 for the Fort Cassin Limestone of western Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
, from which the upper stage of the Canadian Epoch
Canadian Epoch
The Canadian is the Lower or Early Ordovician in North America. The term is common in the older literature and has been well understood for more than a century...
, known as the Cassinian gets its name. The genotype is Cassinoceras explanator (Whitfield). A second species Cassinoceras grande Ulrich & Foerste is also known from the Fort Cassin Limestone. The genus has also been found in Newfoundland
Dominion of Newfoundland
The Dominion of Newfoundland was a British Dominion from 1907 to 1949 . The Dominion of Newfoundland was situated in northeastern North America along the Atlantic coast and comprised the island of Newfoundland and Labrador on the continental mainland...
, the Arctic islands, and on Spitsbergen
Spitsbergen
Spitsbergen is the largest and only permanently populated island of the Svalbard archipelago in Norway. Constituting the western-most bulk of the archipelago, it borders the Arctic Ocean, the Norwegian Sea and the Greenland Sea...
.