Ormoceras sp. A

Kröger, Björn, 2025, The Lyckholm acme of cephalopods - Review of the late Katian (Vormsi-Pirgu regional stages) Ordovician cephalopods of Estonia, European Journal of Taxonomy 978, pp. 1-169 : 21

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/93268783-9662-7032-FD46-FCFBFC4DFA0E

treatment provided by

Plazi (2025-03-07 10:46:31, last updated 2025-03-07 11:32:00)

scientific name

Ormoceras sp. A
status

 

Ormoceras sp. A

Fig. 8H

Material examined

ESTONIA • 1 spec.; Salu; Pirgu Regional Stage; TUG 1745-239 .

Description

Specimen TUG 1745-239 is a ca 113 mm long fragment of a phragmocone with a conch height of 23– 45 mm (angle of expansion = 11°) which is slightly deformed. The conch surface is apparently smooth. The RCL varies between 0.23–0.24 and at a conch height of 27 mm the RSP is ca 0.3. The septal necks are short adnate, and the connecting ring forms barrel-shaped siphuncular segments with a height of 5.8 mm where the length is 6.5 mm (SCR = 0.89). Incipient, symmetric endosiphuncular annuli occur where the conch height is 25 mm.

Remarks

The specimen differs from O. heckeri in having a less expanded siphuncle (SCR = 0.89 in specimen TUG 1745-239 compared with SCR> 1 in O. heckeri ) at comparable conch diameters. However, this single, fragmentarily preserved specimen does not allow for species level determination and detailed comparison with other, e.g., North American species of the genus.