The Genus ''Hemichoanella'' is a small, extinct,

orthoconic An orthocone is the long, cone-shaped shell belonging to several species of ancient nautiloid cephalopod—the prehistoric ancestors of today's marine cephalopod mollusks, including the cuttlefishes, nautiluses, octopuses and squids.; During the ...

nautiloid Nautiloids are a group of cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and species rich, with over 2,500 recorded species. Th ...

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

from the

Lower Ordovician The Early Ordovician is the first epoch of the Ordovician period, corresponding to the Lower Ordovician series of the Ordovician system. It began after the Age 10 of the Furongian epoch of the Cambrian and lasted from to million years ago, unt ...

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

assigned to the orthoceratoid 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 ...

''. ''Hemichoanella'' and the Baltoceratidae are part of the subclass 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 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 ...

and sutures with deep narrow ventral lobes. Septal necks are hemichoanitic, the source of the name, and reach halfway 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 & Glenister) is named in honor of

Alfred Canning Alfred Wernam Canning (21 February 1860 – 22 May 1936) was an Australian surveyor. He is best known as the originator of the Canning Stock Route in Western Australia, a cattle track running through remote desert country between Halls Creek, ...

, who from 1906 to 1908, explored the eastern part of the Desert Basin and who discovered and opened up the

Canning Stock Route The Canning Stock Route is a track that runs from Halls Creek, Western Australia, Halls Creek in the Kimberley (Western Australia), Kimberley region of Western Australia to Wiluna, Western Australia, Wiluna in the Mid West (Western Australia), ...

. ''Hemichoanella'' is considered a particularly advanced baltoceratid (T&G 1954) which differs from '' Baltoceras'' in having longer septal necks.

References

* Teichert & Glenister (T&G) 1954, (Hemichoanella canningi) Bulletins of American Paleontology, Museum of Comparative Zoology, Harvard University

* Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. D.J. Jablonski & M.L. Foote (eds.). ''Bulletins of American Paleontology'' 363: 1–560
Sepkoski's Online Genus Database (CEPHALOPODA)
{{Taxonbar, from=Q5711453 Nautiloids

See also

References