Cameroceras regulus ( Eichwald, 1860 )

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 : 14-15

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/93268783-967B-7028-FDDF-FDA9FB9BFE82

treatment provided by

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

scientific name

Cameroceras regulus ( Eichwald, 1860 )
status

 

Cameroceras regulus ( Eichwald, 1860)

Fig. 5C View Fig

Endoceras regulus Eichwald, 1857: 177 .

Orthoceras turris Angelin in Angelin & Lindström, 1880: 6, pl. 6 figs 14–15.

Endoceras iucundum Stumbur, 1956: 181 , 182, pl. 1 fig. 4, pl. 2 fig. 1, text-fig. 3.

Endoceras regulus – Eichwald 1860:1248, pl. 46 fig. 8.

Cameroceras regulus – Balashov 1968: 70, 101, pl. 5 fig. 3. — Kröger 2013: 7–8 View Cited Treatment .

Endoceras iucundum – Balashov 1968: 101.

Diagnosis

Orthocones with a slightly depressed conch cross section; angle of expansion less than 5°; ornamented with fine transverse striae; sutures directly transverse, ca seven chambers occur on a distance similar to the conch cross section; siphuncular diameter up to 0.5 of corresponding conch cross section; siphuncle marginal, in contact with shell wall; siphuncular segments slightly concave in lateral view; septal necks holochoanitic. (Adopted from Balashov 1968.)

Material examined

ESTONIA • 1 spec.; Harju County, Nõmmeküla quarry; Kõrgessaare Formation, Vormsi Regional Stage ; TUG 939-75 .

Type locality and horizon

Kõrgesaare, Hiiumaa Island, Estonia; Kõrgessaare Formation, Vormsi Regional Stage, late Katian, Ordovician.

Description

Specimen TUG 939-75 is a fragment of a phragmocone with parts of the outer shell preserved. The conch surface is smooth. The conch cross section is circular. The conch has a height of 33–34 mm at a length of 46 mm (angle of expansion = 1.2°). At the conch height of 34 mm the chamber length is 7 mm (RCL = 0.21). The siphuncle is marginally positioned with a diameter of 16 mm where the conch height is 34 mm. The septal necks are holochoanitic and form siphuncular segments, which have in longitudinal view slightly concave outlines ( Fig. 5C View Fig ). The siphuncle is filled with a massive sparitic infill, which preserved no details of the internal structure of the endosiphuncular deposits.

Remarks

The specimen can be identified as a C. regulus based on its large marginal siphuncle and its holochoanitic septal necks.

Subclass Orthoceratoidea Teichert in Teichert & Yochelson, 1967

Order Actinocerida Teichert, 1933

Family Armenoceratidae Troedsson, 1926

Angelin N. P. & Lindstrom G. 1880. Fragmenta Silurica. Samson and Wallin, Stockholm. https://doi.org/10.5962/bhl.title.63278

Balashov Z. G. 1968. Endoceratoidei ordovika SSSR. Isdatelstvo Leningradskogo Universiteta, Leningrad.

Eichwald E. D. von 1857. Beitrag zur geographischen Verbreitung der fossilen Thiere Russlands. Alte Periode. Bulletin de la Societe imperiale des Naturalistes de Moscou 30: 192-212. Available from https://www.biodiversitylibrary.org/page/44192481 [accessed 20 Jan. 2025].

Eichwald E. D. von 1860. Lethaea Rossica ou Paleontologie de la Russie. Premiere Section de l'ancienne Periode, contenant la Flore de l'ancienne Periode et la Faune jusqu'aux Mollusques. Schweizerbart, Stuttgart. https://doi.org/10.5962/bhl.title.52391

Kroger B. 2013. The cephalopods of the Boda Limestone, Late Ordovician, of Dalarna, Sweden. European Journal of Taxonomy 41: 1-110. https://doi.org/10.5852/ejt.2013.41

Stumbur H. A. 1956. O nautiloideah Kohilaskogo arusa (Verhnij Ordovik Pribaltiki). Tartu Riikliku Ulikooli Toimetised 42: 176-185.

Teichert C. 1933. Der Bau der actinoceroiden Cephalopoden. Palaeontographica, A 77: 111-230.

Teichert C. & Yochelson E. L. 1967. Major features of cephalopod evolution. Essays in Paleontology & Stratigraphy RC Moore Commemorative Volume: 162-210.

Troedsson G. T. 1926. On the Middle and Upper Ordovician faunas of northern Greenland. I. Cephalopods. Meddeleser on GrOnland 71: 1-157.

Gallery Image

Fig. 5. Endocerida of the Vormsi–Pirgu regional stages, Estonia. A–B. Cameroceras hasta (Eichwald, 1857). A. Specimen TUG 42-373 from Saaremõisa (Lyckholm) old quarry, Vormsi Regional Stage, dorsal view. B. Dorsal view of the deformed specimen TUG 1745-240 from Saxby old quarry, Pirgu Regional Stage. C. Cameroceras regulus (Eichwald, 1860), polished median section of specimen TUG 939-75 from Nõmmeküla quarry, Vormsi Regional Stage. Scale bars = 10 mm for all figures, same scale in A–B.

Kingdom

Animalia

Phylum

Mollusca

Class

Cephalopoda

Order

Endoceratida

Family

Endoceratidae

Genus

Cameroceras