Dowlingoceras sp. B

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 : 72-73

Dowlingoceras sp. B

Fig. 27J

Material examined

ESTONIA • Paope quarry; Kõrgessaare Formation , Vormsi Regional Stage; TUG 47-866 .

Description

The specimen is a straight, slightly deformed (compressed) fragment of ca eight chambers of the phragmocone and a nearly complete mature body chamber. At the base of the body chamber, the conch diameter is 47 mm, the diameter slightly increases adorally over a distance of ca 20 mm to 60 mm, then continuously decreases to a diameter of 58 mm near the aperture. A shallow and wide constriction is present ca 20 mm from the peristome. The peristome is only partially preserved. The body chamber is ca 60 mm long.

The phragmocone increases in diameter from 42 mm to 57 mm at a length of 52 mm (angle of expansion 16°). The sutures are straight and directly transverse while traces of the siphuncle are present near the conch margin, which are too poorly preserved measure. The remaining traces suggest that the siphuncle was fusiform.

Remarks

The poor preservation of this specimen does not allow further determination. The conch shape combined with the subfusiform siphuncle identify the specimen as a Dowlingoceras .

Figures

Fig. 27 (next page). Breviconic cephalopods from the Vormsi–Pirgu regional stages, Estonia. A. Dowlingoceras kallholnense Frye, 1987, specimen GIT 878-247, from Hosholm shore (tower),Vormsi Island, Pirgu Regional Stage, lateral view. B–C, E. Dowlingoceras sp., specimen GIT 878-249, from Vohilaid shore (E), Vohilaid Island, Pirgu Regional Stage. B. Lateral view. C. View of antisiphuncular side. D. Danoceras sp. A., specimen GIT 878-269, from Hosholm shore (tower), Vormsi Island, Pirgu Regional Stage, lateral view.E. Adoral view. F. Rizosceras teres sp. nov., holotype TUG 1745-188, from Saaremõisa (Lyckholm), Vormsi Regional Stage, lateral view. G–H. Kallholnoceras sp. G. GIT 878- 323, from Hosholm shore (tower), Vormsi Island, Pirgu Regional Stage, lateral view. H. Specimen GIT 878-233, from Vohilaid shore (E), Vohilaid Island, Pirgu Regional Stage, lateral view. I. Dowlingoceras tornense sp. nov., holotype GIT 840-254, from Hosholm shore (tower), Vormsi Island, Pirgu Regional Stage, lateral view. J. Dowlingoceras sp. B, specimen GIT 47-866, from Vohilaid shore (E), Vohilaid Island, Pirgu Regional Stage, lateral view. K. Diestoceras sp., specimen GIT 878-252, from Hosholm shore (tower), Vormsi Island, Pirgu Regional Stage, lateral view. L. Diestoceras stensioei (Troedsson, 1926), specimen GIT 426-987, from Piirsalu quarry, Pirgu Regional Stage. M. Diestoceratidae gen. et sp. indet., specimen TUG 1745-192, from Salu, Pirgu Regional Stage, view from antisiphuncular (?) side. N. Diestoceras stensioei (Troedsson, 1926), specimen GIT 840-264, from Hosholm shore (tower), Vormsi Island, Pirgu Regional Stage, lateral view. Scale bar = 10 mm, same scale in all figures.