Cephalopoda

Dawsonoceras Hyatt, 1884

Taxon description

Kröger & Isakar, 2006

Emended diagnosis. Slender, circular or slightly com-pressed orthocones with symmetrically curved septa andstraight transverse sutures. Sutures parallel to the annulationsin each groove of the annulations. Annulations regularlyspaced, with fine transverse ornament, or growth lines.Growth lines in some species festooned. In some specieslongitudinal ridges that may form nodes at the ridges of theannulations. Siphuncle subcentral in early growth stages, cen-tral in late growth stages, narrow, but expanded within thechambers. Septal necks short suborthochoanitic to achoanitic,in advanced forms short reticulate. Incipient annulosiphuncu-lar deposits, and mural cameral deposits are known.

Selection of related publications
Kröger, B. 2013. The cephalopods of the Boda Limestone, Late Ordovician, of Dalarna, Sweden. European Journal of Taxonomy 41, 41, 1-110. DOI:10.5852/ejt.2013.41
Kröger, B., Ebbestad, J.O.R., Högström, A.E.S., Frisk, A.M. 2011. Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships. Fossil Record 14, 1, 35-53. DOI:10.1002/mmng.201000014
Kröger, B., Isakar, M. 2006. Revision of annulated orthoceridan cephalopods of the Baltoscandic Ordovician. Fossil Record 9, 1, 137-163. DOI:10.1002/mmng.200600005
Stumbur, H. 1955. Eesti NSV ülem-ordoviitsiumi nautiloididest. Diplomitöö; 16 fototahvlit, materjali nimekiri Stumburi tööde kaustas, pp. 1-159.