Specimen ZPAL Ga.9/169 from the Oxfordian (Late Jurassic) of Kłęby, West Pomerania; lateral and apical view.

Holotype BGR X 12918 from the Late Oxfordian of Kłęby (Western Pomerania) in Apertural, Lateral and Apical view.

Diagnoza

The early whorls are elongated and conical, while the later ones widen rapidly. The terminal whorl is constricted. The teleoconch is ornamented by four spiral ribs and orthocline axial ribs. There are 10-12 axial ribs on the juvenile whorls and later the number of ribs increases up to 25. Rounded nodes are developed at the intersections of the axial and spiral ribs. Late in ontogeny the adapicalmost spiral rib and its nodes are slightly stronger than the others. The juveniles have a distinct anterior channel in the aperture that is less clearly developed on the adult whorls. The posterior notch is well developed.

Porównanie

The juvenile shell is similar to the shells of Rhynchocerithium fusiforme (Hébert & Eudes−Deslongchamps,  1860) but its nodes are more blunt than those of the latter.

Autekologia

Występowanie geograficzne

Kłęby (Western Pomerania)

Zasięg czasowy

late Oxfordian

Materiały muzealne

More than 300 specimens (BGR, Buchholz, Beckert, GG, and ZPAL).

Literatura

Dmoch, I. 1971. Osady i fauna górnojurajska z Kłębów na Pomorzu Zachodnim. Studia Societatis Scientarum Torunensis. Sectio C (Geographia et Geologia), 7, 1‒60.

Gründel, J & Kaim, A. 2006. Shallow-water gastropods from Late Oxfordian sands in Kłęby (Pomerania, Poland). Acta Geologica Polonica 56, 121‒157.

Kaim 2004. The evolution of conch ontogeny in Mesozoic open sea gastropods. Palaeontologia Polonica, 62, 3‒83.

Roemer, F.A. 1836. Die Versteinerungen des norddeutschen Oolithen-Gebirges. 218 pp. Hahn’schen Hofbuchhandlung; Hannover.

Schmidt, M. 1905. Über Oberen Jura in Pommern. Abhandlungen der Königlich Preußsischen Geologischen Landesanstalt und Bergakademie, Neue Folge, 41, 1-222.