Eoplacognathus robustus Bergstrom, 1971 from the Mójcza Limestone.

Diagnoza

Flat oz elements with a wide platform , left one T-shaped , right Y-shaped , the external process at least two times as long as the remaining ones.

Synonims:

Amorphognathus sp. 3 LINDSTROM; BEDNARCZYK, 1971;  Amorphognathus complicata RHODES; BEDNARCZYK, 1971; Ambalodus reclinatus FAHRtEUS; BEDNARCZYK, 1971; Eoplacognathus robustus n. sp.: BERGSTROM, 1971; Eoplacognathus lindstroemi robustus BERGSTROM; DZIK, 1976; Eoplacognathus robustus BERGSTROM; BERGSTROM and ORCHARD, 1985.

Porównanie

The platform part of the apparatus was reconstructed by BERGSTROM (1971). The stratigraphically preceding species of the lineage, E. reclinatus (FAHRAEUS , 1966) can be distinguished by shorter external processes, narrower platform (at similar stages of histogeny) and more elevated cusp in the oz elements. The morphology of the platform elements is highly variable making identification of single elements difficult . It is unclear whether the generally large size and robust platform of the elements is a result of some particular dynamics of its Baltic and Polish populations or a stable character.

Autekologia

Występowanie geograficzne

Zasięg czasowy

The lowermost sample, in which well preserved specimens were found, is MA-43
about 0.2 m above the discontinuity . The oldest populations still resemble E. reclinatus in that the external process is somewhat shorter in the oz elements than is typical for E. robustus and may belong to E. reclinatus. It is thus unclear whether the bed immediately above the discontinuity surface with fragmentary specimens represents the E. robustus or E. reclinatus Subzone. The species ranges at least as high as to 0.8 m above the discontinuity.

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.