Paleontology and ichnology of the late Ediacaran Nasep-Huns transition (Nama Group, southern Namibia)

The Nasep and Huns members of the Urusis Formation (Nama Group), southern Namibia, preserve some of the most diverse trace-fossil assemblages known from the latest Ediacaran worldwide, including potentially the world's oldest complex vertical sediment-penetrating burrows. These sediments record relatively diverse communities of bilaterian metazoans existing before the base of the Cambrian and an increase in the intensity of metazoan ecosystem engineering behaviors that could eventually produce profound changes in the character of the Phanerozoic sedimentary record (the agronomic revolution). Despite this, relatively little about this trace-fossil assemblage is known. We explore the Nasep-Huns transition at two localities in the Witputs sub-basin and describe the trace- and body-fossil diversity present in these horizons alongside a paleoenvironmental reconstruction. We document eight unique ichnotaxa from these localities, including well-preserved probes potentially left by priapulids. We also report the first occurrence of Corumbella from Namibia, helping to establish a biostratigraphic link between Namibia, Brazil, Paraguay, Iran, and the southwestern United States. Last, we find that several ichnotaxa, in particular small treptichnids, appear to be preferentially preserved on the bases of gutter casts, hinting at the potential existence of an unusual late Ediacaran preservational window with possible implications for timing the first appearance of key bilaterian behaviors.

Automated summary

This study examines the Nasep and Huns members of the Urusis Formation in southern Namibia, which contain diverse trace-fossil assemblages from the latest Ediacaran. The researchers discover potentially the world's oldest complex vertical sediment-penetrating burrows in these sediments. The findings provide insights into the diverse communities of bilaterian metazoans existing before the Cambrian period and the impact of increased metazoan ecosystem engineering behaviors. The study also establishes a biostratigraphic link between Namibia, Brazil, Paraguay, Iran, and the southwestern United States. Additionally, the researchers identify a possible late Ediacaran preservational window that hints at the timing of the first appearance of key bilaterian behaviors.