Gorbormoceras, Kröger, 2025
publication ID |
https://doi.org/10.5852/ejt.2025.978.2801 |
publication LSID |
lsid:zoobank.org:pub:422E6F06-B4C8-4840-854C-811145D88B32 |
persistent identifier |
https://treatment.plazi.org/id/93268783-9662-7033-FDA9-F9AAFEE5FC8B |
treatment provided by |
Plazi (2025-03-07 10:46:31, last updated 2025-03-07 11:32:00) |
scientific name |
Gorbormoceras |
status |
gen. nov. |
Genus Gorbormoceras gen. nov.
urn:lsid:zoobank.org:act:923963A2-FF6F-4A62-8421-E6B8E2B10E76
Type species
Gorbormoceras vohilaidense gen. et. sp. nov., from Vohilaid shore (E), Vohilaid Island, Estonia; Adila Formation, Pirgu Regional Stage.
Diagnosis
Slightly exogastrically curved, nearly orthoconic longicones with a circular (or nearly so) conch cross section; ornamented with shallow annulation and distinct longitudinal lirae; sutures form shallow lateral lobes; ca five chambers occur at a length equal to corresponding conch cross section; siphuncle slightly eccentrically positioned; septal necks short or absent; siphuncular segments widely expanded with adnate areas at adoral and apical surfaces of septa; endosiphuncular and cameral deposits not known.
Etymology
Combination of the two genus names Gorbyoceras and Ormoceras , because the new genus, in a unique fashion, combines essential features of both genera.
Remarks
The new genus is provisionally assigned to the Ormoceratidae because of its subcentrally positioned, widely expanded siphuncle, and the very short recumbent or absent septal necks. Short or very short cyrtochoantitic to recumbent septal necks and widely expanded siphuncular segments are known from other ormoceratids, such as Ormoceras and Orthonybyoceras Shimizu & Obata, 1935 .
Comparison
Troedssonoceras Foerste, 1928b is similar in having widely expanded siphuncular segments and a longitudinal ornamentation. In Troedssonoceras , the siphuncular shape is similar to Deiroceras (with cyrtochoanitic septal necks), and the connecting ring is not adnate (see, e.g., Flower 1946: 535). Eskimoceras Troedsson, 1926 has an annulated conch and widely expanded siphuncular segments. It differs from the new genus in having cyrtochoanitic septal necks and in lacking a longitudinal ornamentation.
Flower R. H. 1946. Ordovician cephalopods from the Cincinnati region. Part 1. Bulletins of American Paleontology 29 (116): 3-547. Available from https://www.biodiversitylibrary.org/page/10650257 [accessed 20 Jan. 2025].
Foerste A. F. 1928 b. American arctic and related cephalopods. Denison University Bulletin, Journal of the Scientific Laboratories 23: 1-110.
Shimizu S. & Obata T. 1935. New genera of Gotlandian and Ordovician Nautiloids. The Journal of the Shanghai Science Institute, Section II 2: 1-10.
Troedsson G. T. 1926. On the Middle and Upper Ordovician faunas of northern Greenland. I. Cephalopods. Meddeleser on GrOnland 71: 1-157.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
Kingdom |
|
Phylum |
|
Class |
|
Family |