Laureloceras
Encyclopedia
Laureloceras is a genus of slender, smooth-shelled, cyrtoconic or gyroconic barrandeoceratids
from the Middle Silurian of N Am. (Ind, Tenn, ?Ont). Sutures are transverse but may form broad lateral lobes. The siphuncle is subventral - close to the convex side; necks are straight, connecting rings slightly expanded into the camerae. Cameral and siphonal depostis are lacking.
Other cyrtoconic barrandeoceratids include Haydenoceras and Savageoceras
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Flower, (1984) reassigned the Barrandeoceratidae and other barrandeoceroid families to the Tarphycerida, following recognition of the Barrandeocerida being polyphyletic. Other classifications, e.g. Sheverev 2006 include the Barrandeoceratidae in a revived and expanded Basslerocerida which had been abandoned, followeng the speculation in Flower and Kummel (1950) that the basslerocerid family Graciloceratidae might have instead given rise to the Barrandeocerida. The includsion of Laureloceras in the Barrandeoceriatidae is based on Flower and Kummel (1950) and Sweet (1964).
Barrandeoceratidae
The Barrandeoceratidae is a family of coiled nautiloids included in the Tarphycerida that lived from the Middle Ordovician to the Middle Devonian, characterised by mostly compressed shells with a subcentral siphuncle composed of thin-walled segments that may become secondarily ventral..The...
from the Middle Silurian of N Am. (Ind, Tenn, ?Ont). Sutures are transverse but may form broad lateral lobes. The siphuncle is subventral - close to the convex side; necks are straight, connecting rings slightly expanded into the camerae. Cameral and siphonal depostis are lacking.
Other cyrtoconic barrandeoceratids include Haydenoceras and Savageoceras
Savageoceras
The genus Savageoceras is a barrandeoceratid first known from the Middle Silurian of Illinois consisting of rapidly enlarging, depressed cyrtocones with a trapazoidal section; ventral side wider and flatter than dorsal; sides converging on dorsum. Sutures have slight lateral and ventral lobes and...
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Flower, (1984) reassigned the Barrandeoceratidae and other barrandeoceroid families to the Tarphycerida, following recognition of the Barrandeocerida being polyphyletic. Other classifications, e.g. Sheverev 2006 include the Barrandeoceratidae in a revived and expanded Basslerocerida which had been abandoned, followeng the speculation in Flower and Kummel (1950) that the basslerocerid family Graciloceratidae might have instead given rise to the Barrandeocerida. The includsion of Laureloceras in the Barrandeoceriatidae is based on Flower and Kummel (1950) and Sweet (1964).
References
- Flower, R.H. & Kummel, B. 1950. A Classification of the Nautiloidea. Jour Paleo V 24(5), 604-616, Sept 1950
- Flower, R.H. 1984. Bodeiceras, a new Mohawkian Oxycone, with Revision of the older Barranderaoceratida and Discussion of the Status or the Order. Jour Paleo V 58(6), 1372–1379, Nov 1984.
- Sheverev A.A. 2006. The Cephalopod Macrosystem: A Historical Review, the Present State of Knowledge, and Unsolved Problems: 2. Classification of Nautiloid Cephalopods. Paleontological Journal 40(1)
- Sweet, W.C. Nautiloidea-Barrandeocerida.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...
Part K.