Campbelloceras
Encyclopedia
Campbelloceras: a tarphyceratid
with a circular whorl section, only slightly impressed, and a siphuncle
that is close to the venter in all growth stages. Differs from Tarphyceras
in that the rate of expansion is greater, the siphuncle
is proportionally largers, and an impression is shallower. Campbelloceras is known from the L Ord
(U Canad
) of North America where it is widespread.
Campbelloceras may have given rise to the barrandeocerid Plectoceras (Plectoceratidae) through simplification of the connecting rings, and to Tarphyceras through tighter coiling, development of a deeper impression, and reduction in the size of the siphuncle.
Campbelloceras can be conceivably derived from Estonioceras
(Estonioceratidae
). The cross section of Campbelloceras and that of the outer whorl of Estonioceras are similar, except for Campbelloceras being slightly impressed. Both have proportionally large siphuncles, near the venter.
Campbelloceras was named by Ulrich and Foerste in 1936.
Tarphyceratidae
The Tarphyceratidae are tightly coiled, evolute Tarphycerida with ventral siphuncles. The dorsum is characteristically impressed where the whorl presses against the venter of the previous. The Tarphyceratidae are derived from Bassleroceras or possibly from some member of the...
with a circular whorl section, only slightly impressed, and a 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...
that is close to the venter in all growth stages. Differs from Tarphyceras
Tarphyceras
Tarphyeras is a genus of tarphyceratid with whorls rounded in cross section, having a deeply impressed dorsum and a ventral to subcentral siphuncle, known from the Lower Ord of North America...
in that the rate of expansion is greater, 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...
is proportionally largers, and an impression is shallower. Campbelloceras is known from the L Ord
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...
(U Canad
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...
) of North America where it is widespread.
Campbelloceras may have given rise to the barrandeocerid Plectoceras (Plectoceratidae) through simplification of the connecting rings, and to Tarphyceras through tighter coiling, development of a deeper impression, and reduction in the size of the siphuncle.
Campbelloceras can be conceivably derived from Estonioceras
Estonioceras
Estonioceras is an extinct genus of tarphyceridan nautiloid from the Ordovician of Europe.-Sources:* Dinosaur Encyclopedia by Jayne Parsons* Fossils by David Ward-External links:* in the Paleobiology Database...
(Estonioceratidae
Estonioceratidae
The Estonioceratidae is a family of loosely coiled tarphycerids in which the inner side of the whorls, which forms the dorsum, is rounded or flat with no impression; and in which the siphuncle, composed of thick tubular segments, is located ventrally...
). The cross section of Campbelloceras and that of the outer whorl of Estonioceras are similar, except for Campbelloceras being slightly impressed. Both have proportionally large siphuncles, near the venter.
Campbelloceras was named by Ulrich and Foerste in 1936.
Refs
- Flower, R.H 1984; Bodeiceras A New Mohawkian Oxycone, with revision of the Older Barrandeocerida and Discussion of the Status of the Order; Journal of Paleontology V 58, no.6, pp1372–1379, Nov 1984
- Furnish and Glenister 1964; Nautiloidea - Tarphycerida;K355 in the Treatise on Invertebrate PaleontologyTreatise on Invertebrate PaleontologyThe Treatise on Invertebrate Paleontology published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and...
Vol K; Teichert and Moore, (eds) GSA and U of Kansas Press 1964