The importance of Nama Group sediments and fossils to the debate about animal origins

Abstract

The purpose of this review is to draw attention to the contribution that Nama sediments and fossils have made, and potentially can make, to the ongoing debate about metazoan origins. Two important features of this debate concern the nature and systematic position of the late Proterozoic "Ediacaran" fauna as well as the reasons for the sudden appearance in the fossil record of representatives of almost all known animal phyla, during the Early-Middle Cambrian radiation. An additional vexing question is the reason for the apparent absence of preserved representatives of ancestral metazoan lineages in Proterozoic sediments, despite the fact that molecular evidence shows that such lineages had a long his tory, prior to Cambrian times. Nama fossils and their enclosing sediments have made crucial contributions to this debate and will surely continue to do so in the future.