Wardoceras
Encyclopedia
Wardoceras is an extinct nautiloid genus from the late Early Ordovician
of Western Utah, assigned to the orthocerid family, Michelinoceratidae
Shells of Wardoceras are smooth and orchoconic, with a circular cross section and small subcental siphuncle
, the segments of which are ventrally straight and dorsally slightly expanded into the camerae. The siphuncle is completely encircled internally by a thin lining that thickens and thins rhythmically so as to slightly thicken just forward of the septal necks, suggesting an origin in annular deposits. Cameral deposits are well developed and are thick,almost filling the ventral portion of the more apical chambers but also found in dorsal chambers as well.
Wardoceras is represented by the type species, Wardoceras orygoforme which is known only from the holotype
, a 97mm long portion of a phragmocone 13.5mm in diameter at the anterior end; found 25.9m (85ft) above the base of the Wahwah Limestone, section J,Ibex area, Utah.
Wardoceras is named for Jane Shaw Ward, author of the Tajar stories. See also Tajaroceras
, Rangeroceras
, and Veneficoceras
Ordovician
The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...
of Western Utah, assigned to the orthocerid family, Michelinoceratidae
Shells of Wardoceras are smooth and orchoconic, with a circular cross section and small subcental 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...
, the segments of which are ventrally straight and dorsally slightly expanded into the camerae. The siphuncle is completely encircled internally by a thin lining that thickens and thins rhythmically so as to slightly thicken just forward of the septal necks, suggesting an origin in annular deposits. Cameral deposits are well developed and are thick,almost filling the ventral portion of the more apical chambers but also found in dorsal chambers as well.
Wardoceras is represented by the type species, Wardoceras orygoforme which is known only from the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, a 97mm long portion of a phragmocone 13.5mm in diameter at the anterior end; found 25.9m (85ft) above the base of the Wahwah Limestone, section J,Ibex area, Utah.
Wardoceras is named for Jane Shaw Ward, author of the Tajar stories. See also Tajaroceras
Tajaroceras
Tejaroceras is an extinct slender cephalopod from the uppermost Lower Ordovician of western North America, belonging to the Orthocerid family Troedssonellidae....
, Rangeroceras
Rangeroceras
Rangeroceras is an extinct nautiloid cephalopod genus that lived in what is now western North America during the latter part of the Early Ordovician....
, and Veneficoceras
Veneficoceras
Veneficoceras is a member of the rod-bearing Baltoceratidae, an extinct cephalopod family with characteristics of the orthoceratoid Dissidocerida, found in Cassinianage, Lower Ordovician, limestone in western Utah....
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...