Hemichoanella
Encyclopedia
The Genus Hemichoanella is a small, extinct, orthoconic nautiloid cephalopod from the Lower Ordovician of Western Australia assigned to the orthoceratoid family, Baltoceratidae.
Hemichoanella is characterized by its straight, smooth longiconic shell with a circular cross section, large marginal siphuncle and sutures with deep narrow ventral lobes. Septal necks are hemichoanitic, the source of the name, and reach half way to the previous septa. Connecting rings are thick and uniform,each extending from the tip of a septal neck to the tip of the preceding neck. (T&G 1954)
Hemichoanella was named by Teichert and Glenister in 1954 (T&G 1954) for specimens found in Emanuel Creek,Kimberley Division,Western Australia. The type species,Hemichoanella canningi Teichert and Glenister is named in honor of A. W. Canning, who in 1906- 1908 explored the eastern part of the Desert Basin and who discovered and opened up the Canning Stock Route.
Hemichoanella is considered a particularly advanced baltoceratid (T&G 1954) which differs from Baltoceras
in having longer septal necks.
Hemichoanella and the Baltoceratidae are part of the suclass of once diverse and numerous shelled cephalopods known as the Nautiloidea.
Hemichoanella is characterized by its straight, smooth longiconic shell with a circular cross section, large marginal siphuncle and sutures with deep narrow ventral lobes. Septal necks are hemichoanitic, the source of the name, and reach half way to the previous septa. Connecting rings are thick and uniform,each extending from the tip of a septal neck to the tip of the preceding neck. (T&G 1954)
Hemichoanella was named by Teichert and Glenister in 1954 (T&G 1954) for specimens found in Emanuel Creek,Kimberley Division,Western Australia. The type species,Hemichoanella canningi Teichert and Glenister is named in honor of A. W. Canning, who in 1906- 1908 explored the eastern part of the Desert Basin and who discovered and opened up the Canning Stock Route.
Hemichoanella is considered a particularly advanced baltoceratid (T&G 1954) which differs from Baltoceras
Baltoceras
Baltoceras is a member of the Ellesmerocerida, included in the family, Baltoceratidae. The shell of Baltoceras is slender with a subcircular cross section, straight transverse sutures, and a large siphuncle in contact with the venter...
in having longer septal necks.
Hemichoanella and the Baltoceratidae are part of the suclass of once diverse and numerous shelled cephalopods known as the Nautiloidea.
See also
- NautiloidNautiloidNautiloids are a large and diverse group of marine cephalopods belonging to the subclass Nautiloidea that began in the Late Cambrian and are represented today by the living Nautilus. Nautiloids flourished during the early Paleozoic era, where they constituted the main predatory animals, and...