Discosorida, Flower, 1950

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 : 127

Discosorida fam., gen. et sp. indet. D

Fig. 46E–F

Material examined

ESTONIA • 1 spec.; Sutlema old quarry; Kõrgessaare Formation, Vormsi Regional Stage; TUG 1827- 162 .

Description

The specimen is a 50 mm long, fragment of a mature body chamber; it is slightly endogastrically curved with a circular conch cross section.At its base, the conch diameter is 40 mm. The suture, as reconstructed from the base of the body chamber, is straight and transverse with a distinct narrow saddle at the position of the siphuncle. The septal foramen is almost marginal with a width of 5 mm (RSH = 0.125). No traces of the outer shell are preserved.

Remarks

This relatively incomplete fragment of a mature body chamber (likely from a cyrtogomphoceratid) is documented herein, because it cannot be assigned to any of the known genera or species known from Estonia or from the literature. It differs from species of Kiaeroceras in being more strongly curved and in lacking the characteristic narrowly rounded prosiphuncular margin. It differs from species of Strandoceras in having a circular conch cross section.

Figures

Fig. 46. Fragments of indeterminate Discosorida Flower, 1950 of the Vormsi Regional Stage, Estonia. A–B. Discosorida fam., gen. et sp. indet. B, specimen GIT 426-1100 from Paluküla quarry. A. Lateral view. B. Adapical view. C–D. Discosorida fam., gen. et sp. indet. C, specimen TUG 1745-284 from Kõrgessaare quarry, Hiiumaa Island. C. Lateral view. D. Adapical view. E–F. Discosorida fam., gen. et sp. indet. D, specimen TUG 1827-162 from Sutlema old quarry. E. View of the prosiphuncular side. F. Adapical view, note the discosoroid-like siphuncle. G. Adoral view, note the Kiaeroceras-like crosssection. Scale bar = 20 mm, same scale in all figures.