A gnathodont lineage of Mississippian conodonts



Representatives of the disjunct element conodont genus Gnathodus described from lower Mississippian strata (Kinderhookian and Osagean Series) in the Midcontinent of North America illustrate a phylogenetic association composed of ten species. The lineage of G. delicatus — G. punctatus - G. semiglaber, of late Kinderhookian to early Osagean age, has been documented previously. Three distinct forms, G. cf. bilineatus, G. anfetexanus, and G. bulbosus, descended from G. semiglaber in early Osagean time. The latter two continued as parallel lineages; G. bulbosus - G. pseudosemiglaber and G. antetexanus - G. taxanus. In addition, two dead-end lineages, represented by G. typicus and G. cuneiformis, were separately derived from G. antetexanus. Comparison with gnathodont faunas described from Great Britain, Europe, and Australia indicates worldwide distribution of this lineage. The apparent homotaxis of Gnathodus illustrates the value that has been placed on conodonts as tools for regional and intercontinental correlation.