Undetermined undetermined-C Mutvei 2013
Year: 2025
Type: article
Abstract: Multiceratoidea gen. et sp. indet. C Fig. 28K–L Material examined ESTONIA • 1 spec.; Vormsi Island, Hosholm shore (tower locality); Adila Formation, Pirgu Regional Stage; GIT 878-234. Description The specimen is an exogastrically curved fragment of a body chamber and one chamber of the phagmocone. The outer shell is not preserved but the surface was apparently smooth or ornamented with faint transverse lirae. At the base of the body chamber, the conch height and width are 17 mm and 14 mm, respectively (CHI = 1.21). The conch cross section is oval compressed with a narrower conch margin on the prosiphuncular side. The conch has an angle of expansion of 18°. The body chamber has a preserved length of ca 15 mm. In lateral view, both conch margins are curved, convex on the prosiphuncular and concave on the antisiphuncular side. The two preserved septa are 2.2 mm apart (RCL = 0.13), and their sutures form shallow lateral lobes. The siphuncle is located near the convex margin of the conch with a septal foramen which is too poorly preserved to be measured. Remarks The fragmentary character of this specimen does not allow further determination. It is not clear whether this fragment represents a mature individual or a juvenile specimen. Cyrtorizoceras tenue Strand, 1934 has a similar angle of expansion (18°) and a CHI of 1.25 but is too poorly known to be compared with the specimen described herein.
Author: Kröger, Björn
Institutions: University of Helsinki, Finnish Museum of Natural History
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W6949168031
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