Cahabagnathus protoramosus (Chen, Chen & Zhang,1983) from thw Mójcza Limestone.

Diagnoza

The P elements of the apparatus are similar in outline to those of Eoplacognathus foliaceus but in both P₂ elements the row of denticles on the external process is split into two straight segments, the proximal one continuing somewhat further than the point at which it meets the distalone.

Porównanie

All the specimens from the Mójcza Limestone are fragmentary. A much more numerous collection of the species has been derived from coeval strata of the borehole Lesieniec I, where the species also cooccurs with E. reclinatus. All the platform elements of the apparatus show a striking similarity to E. foliaceus, which is certainly the ancestor of the species. The only difference is in the angular bending of the denticle row in the external process of the P₂ elements with a tendency to develop a disruption in their course. These features strongly suggests a phylogenetic proximity to "E." jianyeensis (An & Ding) from the Llandeilo of Tatianbu Formation, Tangshan Hills near Nanjin, China, which connects it with more typical American species of Cahabagnathus.

Autekologia

Występowanie geograficzne

Zasięg czasowy

In South China the species occurs in the E. reclinatus Subzone, in the Lesieniec borehole, NE Poland in the E. robustus and E. lindstroemi Subzones. The occurrences in the Baltic area are of the latter age. In Mójcza it occurs from 0.3 to 1.1 m above the discontinuity (E. robustus Subzone).

Materiały muzealne

ZPAL

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.