Multielement reconstructions of Palmatolepis and Polygnathus (Upper Devonian, Famennian) from the Canning Basin, Australia, and Bactrian Mountain, Nevada

Abstract

Upper Devonian (Famennian) sequences were sampled at two sections in the Canning Basin, Western Australia, and a section at Bactrian Mountain, Nevada, over an interval ranging from the Upper crepida Zone into the Lower marginifera Zone of the standard conodont zonation for the Famennian. Over 30,000 conodont elements have been identified among 43 species and subspecies within six genera. New complete and partial multielement reconstructions are illustrated for: Palmatolepis falcata, P. glabra prima, P. loba, P. minuta minuta, P. perlobata perlobata, P. perlobata maxima, P. quadrantinodosalobata, P. rhomboidea, P. schindewolfi, P. subgracilis, P. wolskae, Polygnathus cf. P. diversus, P. glaber glaber, P. nodocostatus nodocostatus, P. subnormalis, and P. cf. P. triphyllatus. The reconstructions are based on stratigraphic occurrence, detailed morphologic similarities, and a few exceptional low-diversity faunas. Additionally, Palmatolepis adamantea n. sp. is proposed based on the Pa element.A more precise understanding of the taxonomic boundaries of Palmatolepis is achieved through knowledge of the entire apparatus, rather than confined to the Pa elements. Reconstructions presented here provide a more comprehensive understanding of the range of morphologic variation that exists in Palmatolepis, and show that a single generalized elemental plan can be demonstrated for all members of the genus. The differences in the non-Pa elements can thus be used to refine taxonomy and increase understanding of phylogenetic relationships at the specific and subspecific level.