Drepanodus arcuatus Pander, 1856 from the Mójcza Limestone

Apparatuses of Drepanodus species and proposed homology of their elements: .a. Elements of D. arcuatus PANDER,1856 found in the limestone intercalation in the Bukówka quarry (collected by Dr. Wieslaw BEDNARCZYK). b. D. arcuatus PANDER, 1856, late form from the basal parts of the Mójcza Limestone.

Diagnoza

The symmetrical S₀ element with smooth lateral surfaces, its inner margin sharp, in juveniles with smooth flanks, but in adults they may bear angulations. The M elements robust, with a deep round incision above the base. All elements hyaline.

Porównanie

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 more elaborated ornamentation is typical for later D. robustus. "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 P series elements and less elaborated apparatuses.

Autekologia

Występowanie geograficzne

Bukówka quarry and Mójcza. 

Zasięg czasowy

The typical D. arcuatus is confined to the strata below the discontinuity surface in Mójcza

Materiały muzealne

Literatura

Dzik, J. 1994. 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.