Increase in metazoan ecosystem engineering prior to the Ediacaran-Cambrian boundary in the Nama Group, Namibia.

The disappearance of the soft-bodied Ediacara biota at the Ediacaran-Cambrian boundary potentially represents the earliest mass extinction of complex life, although the precise driver(s) of this extinction remain unresolved. The 'biotic replacement' model proposes that an evolutionary radiation of metazoan ecosystem engineers in the latest Ediacaran profoundly altered marine palaeoenvironments, resulting in the extinction of Ediacara biota and setting the stage for the subsequent Cambrian Explosion. However, metazoan ecosystem engineering across the Ediacaran-Cambrian transition has yet to be quantified. Here, we test this key tenet of the biotic replacement model by characterizing the intensity of metazoan bioturbation and ecosystem engineering in trace fossil assemblages throughout the latest Ediacaran Nama Group in southern Namibia. The results illustrate a dramatic increase in both bioturbation and ecosystem engineering intensity in the latest Ediacaran, prior to the Cambrian boundary. Moreover, our analyses demonstrate that the highest-impact ecosystem engineering behaviours were present well before the onset of the Cambrian. These data provide the first support for a fundamental prediction of the biotic replacement model, and evidence for a direct link between the early evolution of ecosystem engineering and the extinction of the Ediacara biota

The first record of late Permian tetrapods from Namibia

The entire Omingonde Formation in Namibia was previously assigned a Triassic age based on the fossil tetrapod fauna discoveredsouthwest of the Waterberg Plateau. However, recently repatriated and newly collected material suggests that the lowermost part of theOmingonde Formation includes late Permian strata, equivalent in age to the upper Endothiodon Assemblage Zone of the South AfricanKaroo Basin. In this study, we document the first record of late Permian tetrapod fossils from Namibia, and provide brief descriptions ofa gorgonopsian skull collected at Mount Etjo in 1996 and the skull of a small dicynodont collected at the same site in 2019, referable tocf. Tropidostoma. This material confirms that there is need for better understanding of the stratigraphy of the Etjo Mountain area, inparticular the position and nature of the unconformity between strata of the Permian Endothiodon and the Triassic Cynognathus assemblage zones.Fil: Mocke, Helke. Geological Survey Of Namibia; NamibiaFil: Kammerer, Christian. North Carolina Museum Of Natural Sciences; Estados UnidosFil: Smith, Roger M. H.. Iziko South African Museum Cape Town; Sudáfrica. University of the Witwatersrand; SudáfricaFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentin

Ernietta_moderate-burial_multiple-individuals_clumped_perpendicular-orientation_0.2ms

COMSOL Multiphysics computational fluid dynamics simulation file

Ernietta_moderate-burial_multiple-individuals_parallel-orientation_0.2ms

COMSOL Multiphysics computational fluid dynamics simulation file

Ernietta_moderate-burial_multiple-individuals_perpendicular-orientation_0.2ms

COMSOL Multiphysics computational fluid dynamics simulation file

Ernietta_shallow-burial_single-individual_parallel-orientation

COMSOL Multiphysics computational fluid dynamics simulation file