Early Cambrian Appalachian Archaeocyaths: Further Age Constraints from the Fauna of New Jersey and Virginia, U.S.A.

New data allow us to correlate the Early Cambrian archaeocyathan faunas of the Appalachian (eastern)and Cordilleran (western) faunal provinces of Laurentia. The precise relationships of fossil assemblages between these provinces have hitherto been controversial, with the correlation of the Elliptocephala asaphoides Fauna posing particular problems. New and revised data (including the new taxa Sekwicyathus tillmani nov. sp. Debrenne & A. Zhuravlev and Archaeosycon balsami nov. sp. Debrenne & A. Zhuravlev on archaeocyathan assemblages from the Appalachians New Jersey and Virginia allow correlation of these assemblages to the middle Bonnia-Olenellus Zone of the Pacific Laurentia (Late Botoman) and the Elliptocephala asaphoides Fauna with the middle-upper Bonnia-Olenellus Zone (Late Botoman-Early Toyonian). The Appalachian archaeocyathan assemblages are not endemic but originated from archaeocyaths of the Pacific Region in or near the Middle Botoman; then, during the Middle Botoman-Late Botoman, they migrated northward along the Appalachian margin of Laurentia (in term of modern coordinates). We discuss here the development and the extent of influence of the Hawke Bay regressive event, and the pattern of archaeocyathan migration as the Appalachian margin of Laurentia drifted northward into equatorial latitudes.