WAGGONER, Benjamin M. Department of Integrative Biology, University of California, Berkeley, CA 94720.
GLOBAL BIOGEOGRAPHY OF EDIACARAN ASSEMBLAGES IN THE LATE PRECAMBRIAN

Macrofossils of the "Ediacara fauna" of the Vendian (late Precambrian) have been interpreted as metazoans, macroalgae, lichens, protists, cyanobacteria, and members of extinct kingdoms. This systematic chaos makes it useful to study these fossils in ways that are independent of systematic hypotheses. Biogeographic data may be analyzed using both phenetics and cladistic methods; these results may be compared with each other and checked against paleotectonic data. This provides an independent test of phylogenetic hypotheses as well as insights into the biology of the biota.
Parsimony analysis of endemism (PAE) identifies a close relationship between Vendian faunas of the Russian Platform, Canada, and south Australia, and between faunas of central England and Newfoundland. Phenetic distance measures largely confirm this result, which is consistent with some (but not all) paleotectonic reconstructions for the period. Brooks parsimony analysis (BPA), based on a phylogenetic hypothesis for "frondlike" Vendian fossils, identifies some of the same area relationships, but fewer areas can be included in this analysis, and the result contains several anomalies. Biotal similarity patterns allow paleotectonically constrained estimates of the times of origin of the Vendian and Cambrian biotas.
Taxonomic diversity at all known Vendian localities shows no sign of the latitudinal diversity gradients of extant biotas; some of the richest assemblages come from localities that were at subpolar latitudes in the Vendian. Apparently, latitudinally variable factors such as temperature, sunlight, and seasonality were not primary controls on Vendian diversity. Since the earliest known Ediacaran organisms have been found in interglacial deposits, the biota may have evolved under cold conditions and been cold-tolerant or eurythermal.