LATE CAMBRIAN TRILOBITES (SAUKIIDAE) AND THEIR IMPLICATIONS FOR PALEOGEOGRAPHY AND PALEOENVIRONMENTAL RECONSTRUCTIONS

Late Cambrian trilobites of the family Saukiidae occupied a variety of shelfal environments across Laurentia and much of core and outboard Gondwanaland. Such widespread distribution is rare among polymerid Cambrian trilobites, and stands in marked contrast with the distribution of their closest relatives, the exclusively Laurentian Dikelocephalidae. Preliminary comparisons of Saukiidae from widely dispersed landmasses show that several supposedly endemic species are morphologically indistinguishable from forms found on separate landmasses, and thus likely constitute synonyms. Given this, a comprehensive, morphology-based revision of the saukiid systematics is now required in order both to better understand relationships within the group, and to refine understanding of the biogeographic distribution of this group. A character matrix for phylogenetic analysis of all well-preserved saukiids has been constructed based strictly on morphological criteria. Character analysis using the PAUP program have been undertaken in order to clarify saukiid relationships and apply this knowledge to Late Cambrian paleogeography. A preliminary cladogram is presented and defended.