Diagnoza

The type population of Spathognathodus commutatus Branson & Mehl, 1941 comes from the Pitkin Limestone at Craig County in Oklahoma (Branson & Mehl 1941) which is of Chesterian (Namurian, Eumorphoceras E2) age, being thus much younger than the Polish occurrences of this lineage but almost coeval and perhaps conspecific with the type species of the gents, Lochriea montanaensis Scott,1942.I am not able to find any significant differences between the apparatus structure of Polish populations from the late Vis6an of Czerna  and those from the Namurian of North America, as reconstructed by Rexroad & Horowitz (1990). L. cracoviensis (Belka, 1985) seems to represent a population of the lineage. The robust appearance of the sp elements, with strongly widened tips of the denticles, may be a feature of advanced histogenetic stages and the difference in respect to other populations from Poland may be a matter of population dynamics. Adult specimens in American populations of L. commutala approach this morphology (see Rexroad & Horowitz 1990; von Bitter & Norby 1994).

Porównanie

Autekologia

Występowanie geograficzne

Zasięg czasowy

Materiały muzealne

Literatura

Dzik, J. 1997. Emergence and succession of Carboniferous conodont and ammonoid communities in the Polish part of the Variscan sea. Acta Palaeontologica Polonica 42, 57-170.