Multiceratoidea

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 : 144

Multiceratoidea gen. et sp. indet. A

Fig. 45C–E

Material examined

ESTONIA • 1 spec.; Pirgu River outcrops; Adila Formation, Pirgu Regional Stage; TUG 1745-299 • 1 spec.; Vormsi Island , Hosholm shore (tower outcrop); Adila Formation, Pirgu Regional Stage; GIT 840-269 • 1 spec.; Vormsi Island , Saxby shore; Kõrgessaare Formation, Vormsi Regional Stage; GIT 878-76 .

Description

GIT 840-269 ( Fig. 45C ) is a fragment of a phragmocone, exogastrically curved with an angle of expansion of 20° at a conch height between 37 mm and 26 mm. At its apical end, the height and width are 26 mm and 23 mm, respectively (CHI = 1.13). The septa are 6 mm apart where the conch height is 31 mm (RCL = 0.19), and the sutures form lateral lobes. The siphuncle is marginally positioned and expands into the chambers. The septal foramen is 2.5 mm wide where the conch height is 26 mm (RSH = 0.1).

GIT 840-76 ( Fig. 45D–E ) is an exogastrically curved fragment of a phragmocone with a conch height and width of 20 mm and 18 mm, respectively, at its apical end (CHI = 1.11) with sutures which form lateral lobes. The sutures are 5 mm apart where the conch height is 23 mm (RCL = 0.22). The conch curvature, CHI, RCL and curvature of the suture line are similar to that of GIT 840-269.

TUG 1745-299 is a fragment of a phragmocone of an apparently exogastric cyrtocone with a conch width of 24 mm. It is closely similar to the two specimens, but too poorly preserved to be measured.

Remarks

These three specimens are described in order to document the presence of a relatively large, exogastrically curved brevicone, different from the genera and species described herein, but not well enough known to determine the order, genus, or species.

Figures

Fig. 45. Fragments of indeterminate Multiceratoidea Mutvei, 2013 of the Vormsi–Pirgu regional stages, Estonia. A–B. Discosorida fam., gen., et sp. indet. A, Vohilaid shore (E), Vohilaid Island, Pirgu Regional Stage. A. Specimen GIT 878-188, lateral view. B. Specimen GIT 878-189, adapical view, position of the siphuncle toward the right. C–E. Multiceratoidea fam., gen., et sp. indet. A. C. Specimen GIT 840- 269, from Hosholm shore (tower) Pirgu Regional Stage, lateral view. D–E. Specimen GIT 878-76, from Saxby shore, Vormsi Island, Vormsi Regional Stage. D. Lateral view. E. View of the concave side of conch curvature, position of siphuncle unknown. Scale bar = 20 mm, same scale in all figures.