Eoplacognathus robustus Bergström , 1971 from the Mójcza Limestone.

Diagnoza

Flat P₂ 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.

Porównanie

The stratigraphically preceding species of the lineage, E. reclinatus,  can be distinguished by shorter external processes, narrower platform (at similar stages of organogeny) and more elevated cusp in the P₂ 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

Mójcza; Baltic area and other temperate climate regions of the Ordovician.

Zasięg czasowy

The lowermost sample, in which well preserved specimens were found, is about 0.2 m above the discontinuity . The oldest populations still resemble E. reclinatus in that the external process is somewhat shorter in the P2 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

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.