East-Gondwana/Laurentia trilobite connections—What do they tell us?

摘要

The geography of the Cambrian world depends largely on analysis of distribution patterns of marine faunas dominated by trilobites. Early Cambrian contrasts between east-Gondwanan faunas dominated by redlichiids and Laurentian faunas dominated by olenellids are well known and suggest a significant distance between these continents. On the other hand, slopeand/or cool-water facies contain numerous shared taxa (particularly agnostoids and oryctocephalids in the middle Cambrian). However, these taxa tell us little about geographic relations between the two continents. Apparent similarities among some less common polymerid trilobites, beginning in late early Cambrian time, may contribute significantly to a refined understanding of the geographic relation of these parts of the Cambrian world. However, taxonomic complications have hindered the usefulness of these taxa. A future project for the Cambrian Subcommission might be sponsorship of small international workshops among taxonomists, much like those developed by conodont workers. Such workshops, perhaps focused on stage-size intervals, might be able to reach consensus on a simplified and reproducible polymerid taxonomy of value for biogeographic analysis.