Drepanodus arcuatus Pander, 1856 from the Mójcza Limestone.

Apparatus of Drepanodus arcuatus Pander, 1856.

Diagnoza

The symmetrical tr element with smooth lateral surfaces, its inner margin sharp, in juveniles with smooth flanks, but in adults they may bear angulations. The ne elements robust , with a deep round inci sion above the base. All elements hyaline.

Porównanie

Two main element types were identified by LINDSTROM(1971), the apparatus reconstruction has been further developed by VAN WAMEL (1974), LOFGREN (1978), and DZIK (1990). During the evolution of this Drepanodus lineage elements become more and more prominently ornamented along their inner edges. In the Arenig some rare specimens (usually large ones) bear three ridges along this edge but I was not able to find any with moreel aborated ornamentation, which is typical for later D. robustus. Somewhat arbitrarily, I assign to D. arcuatus the se populations transitional to D. robustus that still did not develop five ridges along the inner edge in adult elements. "Protopanderodus n. sp. A" MCCRACKEN, 1989 from the P. serra Zone of Northern Yukon, Canada, may be a successor of D. arcuatus. Oblique bases make it superficially similar to some species of Protopanderodus which, however, have quite different "platform" series elements and less elaborated
apparatuses.

Autekologia

Występowanie geograficzne

Zasięg czasowy

Materiały muzealne

Literatura

Dzik, J. 1994a Conodonts of the Mójcza Limestone. In: J. Dzik, E. Olempska, & A. Pisera. Ordovician carbonate platform of the Holy Cross Mountains. Palaeontologia Polonica 53, 43-128.