Element association and morphology in some Middle Ordovician platform-equipped conodonts

摘要: Abstract Conodont elements other than those with platform ledges along the processes have often been unrecognized or disregarded in reconstructions and phylogenetic discussions of Ordovician “platform conodont genera.” The are larger element types exhibit more rapid evolutionary changes morphology. Nevertheless, to understand evolution of, relationships between among genera,” it is necessary also consider associated ramiform geniculate elements. Thus, on basis large collections, together comprising 10,800 from Sweden southern China, all Lenodus antivariabilis (An, 1981), L. variabilis (Sergeeva, 1963), Yangtzeplacognathus crassus (Chen Zhang, 1993) Eoplacognathus pseudoplanus (Viira, 1974) described discussed. All these species had seven morphologically distinct types, probably seventeen individual each apparatus. Ancestors descendants spe...