SECRETS OF THE HARPETIDS: PHYLOGENY, DISPARITY, AND MASS EXTINCTION RESPONSE IN THE TRILOBITE ORDER HARPETIDA
Exemplar species from a broad selection of harpetid genera, along with ptychopariid and redlichiid out groups, are included in the matrix. These taxa were coded from published figures and from direct observation of specimens held in the collections of the Yale Peabody Museum of Natural History. From the matrix, a hypothetical tree of harpetid phylogenetic relationships was generated. The topology of this tree indicates support for harpetid monophyly but throws doubt onto the previous hypotheses of the internal relationships of the group. Disparity analysis of Harpetida reveals a significant decline in morphological diversity across the Late Ordovician mass extinction boundary, with slow recovery beginning in the Silurian and continuing into the Devonian.