''Laureloceras'' is a genus of the
tarphycerid family
Plectoceratidae
The Plectoceratidae is a family of tarphycerids in the suborder Barrandeocerina established as a place for the genus '' Plectoceras''; defined (Sweet 1964) simply as coiled, costate barrandeocerids with subcentral adult siphuncle.
According to ...
that lived during the Middle Silurian in what is now North America.
The shell of ''Laureloceras'' is a smooth, slender, compressed cyrtocone or gyrocone with the venter more narrowly rounded than the dorsum.
Sutures are transverse but may form broad lateral lobes. The siphuncle is subventral - close to the outer rim; necks are straight, connecting rings slightly expanded into the chambers. Cameral and siphonal deposits are lacking.
''Laureloceras'' was previously included in the
Barrandeoceratidae (Flower, 1950, Sweet, 1964) but was removed (Flower, 1984) primarily on the bases of the subventral siphuncle (Barrandeoceratid siphuncles are central - subcentral. Reassignment to the Tarphycerida from the Barrandeocerida is based on barrandeoceratid taxa being polyphyletic (having more than one common ancestor).
Barrandeocerina
The Barrandeocerina comprise a suborder of Early Paleozoic nautiloid cephalopods, primitively coiled but later forms may be cyrtoconic, gyroconic, torticonic, and even breviconic, all having empty siphuncles with thin connecting rings. The Bar ...
is retained as a parking place for evolved tarphycerids with thin connecting rings.
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.
* Sweet, W.C. 1964. Nautiloidea-Barrandeocerida; Treatise on Invertebrate Paleontology, Part K. Grologival Society of America and University of Kansas Press.
{{Taxonbar, from=Q6500089
Prehistoric nautiloid genera