Abstract

Several phylogenetic hypotheses have been put forward to explain the relationships between species of the conodont genera Hindeodus and Isarcicella across the Permian–Triassic boundary. These phylogenetic models can be tested by cladistic analysis. A data matrix of 25 P1 element characters for 22 species of Hindeodus and Isarcicella has been analysed and the resulting cladogram converted to a phylogenetic tree using the ranges of taxa in the Meishan Section, China. The proposed phylogeny does not concur entirely with any of those forwarded in the previous literature, and Hindeodus parvus is not resolved as a direct descendant of Hindeodus praeparvus. Species assigned to the genus Isarcicella form a natural group, with Hindeodus species apparently representing a para- phyletic array. The Hindeodus + Isarcicella clade survived the end-Permian extinction event well, with Hindeodus species that became extinct just above the boundary replaced by radiation within the Isarcicella clade. h Cladistics, conodonts, phylogeny, Permian, Triassic.