Siljanoceras, Kröger, 2013

Kröger, Björn, 2013, The cephalopods of the Boda Limestone, Late Ordovician, of Dalarna, Sweden, European Journal of Taxonomy 41, pp. 1-110 : 82

publication ID

https://doi.org/ 10.5852/ejt.2013.41

publication LSID

lsid:zoobank.org:pub:A2F1B9ED-870A-466E-B35E-BD5DA782476E

DOI

https://doi.org/10.5281/zenodo.3815190

persistent identifier

https://treatment.plazi.org/id/AD4D9054-CD35-6A37-F0C8-4620FE91FBE0

treatment provided by

Carolina

scientific name

Siljanoceras
status

 

Siljanoceras sp. A.

Figs 36 View Fig A-B, 38

Material

One specimen ( PMU 26917), Kallholn, Siljan District, Sweden; Boda Limestone, Boda Core Member, late Katian.

Description

Specimen PMU 26917 is a mildly deformed portion of a slightly curved phragmocone, 23 mm long with a conch height of ca. 22–40 mm and a conch width of ca. 20–40 mm (angle of expansion ca. 38°) ( Fig. 36A, B View Fig ). The original shape of the conch cross section is difficult to evaluate, but was probably slightly depressed. The conch surface is poorly preserved and no signs of ornamentation are visible. The sutures are nearly transverse and have a distance of ca. 0.17 of the corresponding conch cross section.

The position of the septal perforation is eccentric (SPR 0.4). The siphuncular segments are barrel-shaped and widely expanded with maximum diameter of ca. 0.18 of the corresponding conch cross section. The septal necks are achoanitic.

Remarks

This fragmentarily preserved specimen differs from Siljanoceras varians gen. et sp. nov. in having a less curved, more expanded conch with a less eccentric siphuncle, that appears slightly more expanded within the shell. The general conch form is similar to that of Siljanoceras gen. nov. and it is therefore assigned to this genus. However, a species determination is impossible based on this imperfectly known specimen.

PMU

Paleontological Museum of Uppsala

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