A formerly unknown fossil-bearing locality in the lower part of the Witpoort Formation (Witteberg Group, Cape Supergroup) is described from the Eastern Cape (South Africa). Uniquely for these strata, it provides evidence for a back-barrier lagoon hosting a monospecific lingulid brachiopod fauna. This represents the youngest record of marine invertebrates within the Cape Supergroup. The occurrence extends the age range of the genus Dignomia Hall into the Famennian Stage, contrary to previous estimates of an Ordovician to mid-Devonian range. Abundant lingulid brachiopod valves are associated with plant and fish remains within a laterally extensive, up to nine-meter-thick mudstone. Shell compressions are concentrated in patches within the upper portion of the horizon and are preserved parallel to bedding as well as perpendicular and oblique to bedding (apparently in situ). Plant fossils exhibit a greater degree of transport than in other studied Witpoort Formation mudrock layers (Coombs Hill and Waterloo Farm). The monospecifity of the shelly invertebrate fauna derives from environmental stress and lingulid brachiopods' unusual ability to tolerate fluctuating environmental conditions, including salinity, oxygen levels, and temperature. Ichnofauna within the deposit include, among others, Nereites and ‘Spirophyton', suggesting opportunistic colonization of the substrate by deposit feeding invertebrates in a marine-dominated backshore setting. The Late Devonian was a time of global environmental disequilibrium, characterized by periodic flooding of continental margins and massive biotic overturn. Ongoing research into eustatic and environmental changes recorded within the Witpoort Formation uniquely provide insights into high latitude conditions during the Famennian.
Coombs Hill, a new fossil locality in the Witpoort Formation (Witteberg Group) of South Africa, preserves a record of Famennian (Late Devonian) life in Gondwana. Fossil plants collected at Coombs Hill are preliminarily assigned to several classes. Shelly invertebrates include a variety of bivalve mollusc forms, some of which appear to be preserved in life position. Biodiversity at Coombs Hill is comparable to that of the well-known Waterloo Farm lagerstätte in ordinal diversity, but exhibits differences in species composition. Ongoing taxonomic analysis will provide a rare window into the ecology of high-latitude environments during this pivotal stage of Earth history, which immediately preceded the end-Devonian extinction. Sandstone dominated sedimentary facies at Coombs Hill suggest a high-energy coastal marine setting, with brackish back-barrier estuarine/lagoonally derived fossiliferous mudstones. Exact stratigraphic placement within the Witpoort Formation is hampered by structural deformation, and precise age comparisons with Waterloo Farm are currently tenuous.
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