Pseudopolygnathus marburgensis marburgensis and Pseudopolygnathus marburgensis trigonicus were believed to be different conodont subspecies. However, paleontological data indicate those two are stages of evolution of a single lineage. Research is also focused on evolutionary changing of appearance and evolution of growth and development calibrated precisely with incremental layers. This study could have potential influence on dating Late Devonian rocks based on evolutionary transformations.