Conodont Apparatus Reconstruction from the Lower Carboniferous Hart River Formation, Norther Yukon Territory

Abstract

Conodonts sampled from the Lower Carboniferous Hart River Formation have yielded abundant, well-preserved elements with a relatively low diversity of species. In addition, they do not display much platform-overrepresentation, a phenomenon affecting the majority of Late Paleozoic conodont samples. These qualities make the Hart River conodont samples ideal for statistical apparatus reconstruction. The elements were divided into groups based on morphology and counted. Cluster analysis, in addition to empirical observations made during the counting process, was then used to reconstruct the original apparatus composition for the species present. Five partial to complete apparatus reconstructions were made, belonging to the species Bispathodus sp. A, Bispathodus stabilis, Gnathodus homopunctatus, Gnathodus texanus, and Vogelgnathus gladiolus. The co-occurrence of these species indicate an early Visean age for the Hart River Formation. This differs slightly from the late Visean to early Serpukhovian age previously suggested for the Hart River Formation. The apparatus reconstructions prompted the reassignment of what has been called Lochriea homopunctatus in previous studies to the genus Gnathodus, and the new identification of Bispathodus sp. A, formerly interpreted as Rachistognathus prolixus. The apparatus reconstructions made in this study show new morphology for taxa that are both stratigraphically and evolutionarily important, indicating greater taxonomic complexity than was previously identified.