Rodzaj Nicollidina Dzik, 2002
Gatunek typowy Opis Diagnosis.- Minute elements with reduced medial process in S0 (tr) element and shortened processes in S1 (lo) and S2 (pl) elements which still preserved linear arrangement. Remarks.- Species included here in this new genus were previously classified in Ozarkodina Branson & Mehl, 1933, the type species of which is a Silurian primitive ozarkodinid with biramous S0 (tr) elements. Its lineage probably survived to the late Palaeozoic being represented there by species of Hindeodus Rexroad & Furnish, 1964 and Synclydagnathus Rexroad & Varker, 1992. They all show angular profiles of bases of S0 (tr), S1 (lo) and S2 (pl) elements, unlike N. brevis. In the latter, the ramiform elements of the apparatus look rather like early juvenile elements of typical polygnathids. Most likely, evolutionary diminution in size resulted in a secondary reduction of the medial process of the S0 element. Nicollidina is thus a secondarily simplified member of the Polygnathidae, not the Spathognathodontidae. Species included.- Along with type species also N. raaschi (Klapper & Barrick, 1983) and N. postera (Klapper & Lane, 1985). Synonimy Zasięg czasowy Eifelian to Frasnian Literatura Dzik, J. 2002. Emergence and collapse of the Frasnian conodont and ammonoid communities in the Holy Cross Mountains, Poland. Acta Palaeontologica Polonica 47 (4): 565-650 |
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