SILURIAN ODONTOPLEURINAE (TRILOBITA) FROM THE CAPE-PHILLIPS FORMATION, ARCTIC CANADA

Odontopleurids are a diverse component of rich silicified trilobite fa unas recovered from the Wenlock and Ludlow of the Cape Phillips Format ion, central Canadian Arctic. Odontopleurinae and Acidaspidinae are co mmon, but Ceratocephalinae and Koneprusiinae are also represented. Thi s work treats all of the Odontopleurinae, with the exception of the ge nus Acanthalomina Prantl and Pribyl, 1949. New species of kettneraspis Prantl and Pribyl, 1949, include the upper Sheinwoodian K. wrightae, the lower Homerian K. lindoei, and the Gorstian K. caldwelli. Rare spe cimens assigned to Odontopleura Emmrich, 1839, and Radiaspis Richter a nd Richter, 1917, occur in the Sheinwoodian of the central Arctic. Edg ecombeaspis (type species E. johansonae new species) is proposed for a n odontopleurine clade endemic to Laurentia, and in the Silurian restr icted to northern Laurentia. Cladistic analysis yields a hypothesis of ingroup structure that is in general calibrated with stratigraphic se quence. An exception is a group of Telychian species from the Mackenzi e Mountains, whose stratigraphic sequence was used to support a previo us hypothesis of an ancestral-descendant lineage. The cladistic result indicates that the stratigraphic pattern is the inverse of the phylog enetic pattern: the stratigraphically lowest species in the proposed l ineage is the most derived, and the highest is most primitive. In addi tion to the type, new species of Edgecombeaspis include the mid-Sheinw oodian E. jahansi and the lower Homerian E. soehni. Edgecombeaspis app arently became extinct in the Homerian. The species Kettneraspis lenzi (Chatterton and Ferry, 1983) and Radiaspis cf. R. norfordi (Chatterto n and Ferry, 1983) occur in the central Arctic, and further strengthen previous correlations with strata in the central Mackenzie Mountains, Northwest Territories.