Clarkoceras has a rapidly expanding, laterally compressed, relatively short, endogastrically cyrtoconic shell; The upper or dorsal side is more strongly convex longitudinally than the lower or ventral side is concave. Sutures are essentially straight and close spaced indicating very short camerae (chambers). The siphuncle is relatively large, 0.3 the dorsoventral dimension and is ventral, although not necessarily marginal. (Flower 1964, Furnish and Glenister 1964). Septal necks are straight, reaching about half way back to the previous septum and the connecting rings are thick and layered
Taxonomyedit
Clarkoceras was first thought by Clarke to be a pilocerid, who in 1897 give it the name Piloceras newton-winchelli. Ruedemann in 1905 recognized this as belonging to the Ellesmerocerida and renamed it Clarkoceras newton-winchelli (Clarke), which became the genotype.
Distribution and Rangeedit
The earliest known Clarkoceras comes from the upper Trempealeauan Wanwankou Member of the Fengshan Formation in northern China, one of twelve ellesmeroceratid genera from the upper Late Cambrian. (Chen and Teichert 1983, Teichert 1988). In North America Clarkoceras is found in early Lower Ordovician, Gasconadian age shallow marine sediments near Smith Basin, State of New York, the Llano Uplift of Central Texas, and the El Paso Group of the eastern Rocky Mountains of Trans-Pecos Texas and Southern New Mexico.
Referencesedit
Jun-yuan, Chen; Teichert, Curt (1983). "Cambrian cephalopods". Geology. 11 (11). Geological Society of America: 647–650. Bibcode:1983Geo....11..647J. doi:10.1130/0091-7613(1983)11<647:CC>2.0.CO;2.
Flower, R.H., 1964, The Nautiloid Order Ellesmerocerida (Cephalopoda). New Mexico Bureau of Mines and Mineral Resources Memoir 12, Socorro, NM
Furnish and Glenister, 1964, Nautiloidea-Ellesmerocerida, in Teichert and Moore (Eds.), The Treatise on Invertebrate Paleontology Partl K, Nautiloidea. GSA and University of Kansas Press
Ruedemann, R., 1905, The Structure of Some Primitive Cephalopods, New York State Museum Bulletin 80, pp. 296–341
Teichert, C. 1988, Main Features of Cephalopod Evolution, in M.R Clarke and E.R.Trueman (Eds.), The Mollusca. Academic Press
April 21, 2024
clarkoceras, genus, breviconic, ellesmerocerid, cephalopods, only, genera, known, have, crossed, from, late, cambrian, trempealeauan, into, early, ordovician, gasconadian, flower, 1964, teichert, 1988, other, being, ectenolites, temporal, range, late, cambrian. Clarkoceras is a genus of breviconic ellesmerocerid cephalopods one of only two genera known to have crossed from the Late Cambrian Trempealeauan into the Early Ordovician Gasconadian Flower 1964 Teichert 1988 the other being Ectenolites ClarkocerasTemporal range Late Cambrian Early Ordovician PreꞒ Ꞓ O S D C P T J K Pg N Scientific classification Domain Eukaryota Kingdom Animalia Phylum Mollusca Class Cephalopoda Subclass Nautiloidea Order Ellesmerocerida Family Ellesmeroceratidae Genus ClarkocerasRuedemann 1905 Contents 1 Description 2 Taxonomy 3 Distribution and Range 4 ReferencesDescription editClarkoceras has a rapidly expanding laterally compressed relatively short endogastrically cyrtoconic shell The upper or dorsal side is more strongly convex longitudinally than the lower or ventral side is concave Sutures are essentially straight and close spaced indicating very short camerae chambers The siphuncle is relatively large 0 3 the dorsoventral dimension and is ventral although not necessarily marginal Flower 1964 Furnish and Glenister 1964 Septal necks are straight reaching about half way back to the previous septum and the connecting rings are thick and layeredTaxonomy editClarkoceras was first thought by Clarke to be a pilocerid who in 1897 give it the name Piloceras newton winchelli Ruedemann in 1905 recognized this as belonging to the Ellesmerocerida and renamed it Clarkoceras newton winchelli Clarke which became the genotype Distribution and Range editThe earliest known Clarkoceras comes from the upper Trempealeauan Wanwankou Member of the Fengshan Formation in northern China one of twelve ellesmeroceratid genera from the upper Late Cambrian Chen and Teichert 1983 Teichert 1988 In North America Clarkoceras is found in early Lower Ordovician Gasconadian age shallow marine sediments near Smith Basin State of New York the Llano Uplift of Central Texas and the El Paso Group of the eastern Rocky Mountains of Trans Pecos Texas and Southern New Mexico References editJun yuan Chen Teichert Curt 1983 Cambrian cephalopods Geology 11 11 Geological Society of America 647 650 Bibcode 1983Geo 11 647J doi 10 1130 0091 7613 1983 11 lt 647 CC gt 2 0 CO 2 Flower R H 1964 The Nautiloid Order Ellesmerocerida Cephalopoda New Mexico Bureau of Mines and Mineral Resources Memoir 12 Socorro NM Furnish and Glenister 1964 Nautiloidea Ellesmerocerida in Teichert and Moore Eds The Treatise on Invertebrate Paleontology Partl K Nautiloidea GSA and University of Kansas Press Ruedemann R 1905 The Structure of Some Primitive Cephalopods New York State Museum Bulletin 80 pp 296 341 Teichert C 1988 Main Features of Cephalopod Evolution in M R Clarke and E R Trueman Eds The Mollusca Academic Press Retrieved from https en wikipedia org w index php title Clarkoceras amp oldid 1214662027, wikipedia, wiki, book, books, library,
