Diagnoza

Juvenile conch discoidal with open umbo about 3 mm wide; at the venter internal thickenings parallel to the aperture.

Porównanie

An angulation of the dorsolateral saddle marks an incipient dorsolateral lobe of the same kind as in D. globosoides. The difference between these species consists in a less globose conch shape and internal thickenings parallel to aperture in the Jabłonna population, which seems also to be stratigraphically older that that at Łagów.

Early stages of the ontogeny and the conch form indistinguishable from typical species of Cheiloceras make this species a good connecting link between families.

The holotype of the species is a juvenile 17 mm in diameter with well exposed suture, rather poorly preserved but the conch globosity and narrow umbo at such ontogentic stage fits that of the Jabłonna specimens, making it unlike more advanced species of Dimeroceras. In Otto Schindewolf ’s sample “Schicht 4”, mentioned above in connection with Cheiloceras inversum, there are specimens with a depressed area surrounding the closed umbo and probably representing a button-like internal thickening. Such specimens were classified by Sobolev (1914) in his C. depressum.

Autekologia

Występowanie geograficzne

Jabłonna; reworked at Sieklucki’s brickpit in Kielce.

Zasięg czasowy

Probably early part of the C. marginifera Zone.

Materiały muzealne

ZPAL: 5 specimens.

Literatura

Dzik, J. 2006. The Famennian "Golden Age" of conodonts and ammonoids in the Polish part of the Variscan sea. Palaeontologia Polonica 63, 1-359.