Application of numerical cladistic analyses to the Carnian–Norian conodonts: a new approach for phylogenetic interpretations

Abstract

The high intraspecific variability of conodont platform elements in the upper Carnian–lower Norian interval and the proliferation of numerous species in this relatively short time have generated many problems for the understanding of Late Triassic conodont phylogeny, systematics and taxonomy. Since Late Triassic natural assemblages are still unknown, we have applied cladistic methodologies to investigate the evolution of Carnian–Norian conodont platforms and to infer more precise phylogenetic relationships among taxa. Numerical cladistic analysis was undertaken of species belonging to the five Late Triassic genera Paragondolella, Carnepigondolella, Metapolygnathus, Epigondolella and Norigondolella. A taxon–character data matrix describing the distribution of 64 characters amongst two outgroups and 31 ingroup taxa was compiled and processed using PAUP* 4.1. Our analyses show the evolutionary and systematic value of certain morphological characters, and lead to a reinterpretation of the phylogenetic position of the genera considered: Metapolygnathus, Epigondolella and Norigondolella are monphyletic taxa, Paragondolella represents a polyphyletic assemblage of basal members of the ingroup, and Carnepigondolella a paraphyletic group including primitive forms of the Metapolygnathus and Epigondolella lineages. Our analyses also clarify the systematic position of ‘Metapolygnathus communisti B’ and confirm the existence of four new species: Carnepigondolella angulata sp. nov., Epigondolella heinzi sp. nov., Epigondolella miettoi sp. nov. and Norigondolella trinacriae sp. nov.