Danoceras breve Strand, 1934

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 : 60

Danoceras breve Strand, 1934

Fig. 24B

Danoceras breve Strand, 1934: 81–82 , pl. 11 fig. 6, pl. 13 fig. 1.

Danoceras breve – Flower 1946: 420. ― Dzik 1984: 67, text-fig. 18.11.

Diagnosis

Danoceras with compressed elliptical to oval conch cross section (CHI = 1.3–1.4); mature body chamber with maximum conch height near its base with height of ca 42 mm; apical angle of the phragmocone ca 25°; conch surface, with distinct constriction near peristome and amphora-like apertural opening.

Material examined

ESTONIA • 1 spec.; Haapsalu holm; Adila Formation, Pirgu Regional Stage; GIT 426-988 .

Type locality and horizon

Vestre Svartøy, Ringerike, Norway; Bønsnes Formation, late Katian.

Description

The specimen is a slightly deformed fragment of a phragmocone and the mature body chamber. The maximum conch height of the specimen (41 mm) is at the base of the body chamber. There, the conch width is 30 mm (CHI = 1.37). The preserved part of the body chamber is 27 mm long.

The phragmocone increases in conch height from 23 mm to 40 mm at a length of 38 mm (angle of expansion 25°). At the adoral end of the phragmocone, the chamber length is 6 mm (RCL = 0.15). Traces of a weak longitudinal striation are preserved on the surface of the internal cast of the phragmocone. The conch surface is not preserved. The conch is very slightly curved with a thin (ca 3 mm in diameter) siphuncle preserved near the conch margin at the convex side of the conch curvature.

Remarks

This specimen is very similar in dimensions and conch shape to the types of Danoceras breve and although details of the siphuncle are not examined, the thin marginal siphuncle is indicative of a species of Danoceras .

Figures

Fig. 24. Danoceras Troedsson, 1926 from the Vormsi–Pirgu regional stages, Estonia. A. Danoceras oviforme sp. nov., holotype GIT 878-108, from Moe trench, Vormsi Regional Stage, lateral view. B. Danoceras breve Strand, 1934, holotype GIT 426-988, from Haapsalu holm, Haapsalu, Pirgu Regional Stage, lateral view. C. Danoceras oviforme sp. nov., specimen GIT 80-510, from Piirsalu quarry, Pirgu Regional Stage, lateral view prosiphuncular side toward right. D. Danoceras piersalense (Teichert, 1930) comb. nov., specimen GIT 840-271, from Hosholm shore (tower), Vormsi Island, lateral view. E. Danoceras vohilaidense sp. nov., holotype GIT 878-273, from Vohilaid shore (E), Vohilaid Island, Pirgu Regional Stage, lateral view, prosiphuncular side left.F–H. Danoceras piersalense specimen GIT 840-93, from Hosholm shore (tower), Vormsi Island, Pirgu Regional Stage. F. Lateral view. G. Adapical view, prosiphuncular side to the right. H. Specimen TUG 1745-302, from Pirgu River outcrop, Pirgu Regional Stage, lateral view. Scale bar = 10 mm, same scale in all figures.