Southern African Phanerozoic marine invertebrates: Biogeography, pal˦oecology, climatology and comments on adjacent regions

Abstract

The Palaeozoic marine invertebrate fossil record in southern Africa is characterised by extensive data for the Early and Middle Devonian but extremely limited or absent for other Palaeozoic Periods. The Mesozoic Era is lacking in marine invertebrate fossils for the Triassic, Late Jurassic, and Cretaceous. For the Cenozoic Era there is limited marine megafossil information. Overall, in benthic, cool waters, Palaeozoic, marine megafossils from southern Africa appear to represent relatively low diversity communities, when compared to ecologically comparable warm water environments elsewhere. However, the marine benthic Cretaceous and Cenozoic faunas of southwestern Africa are typically diverse warm water types, until the later Miocene when cool waters again prevailed. The Benguela Current clearly influenced lower diversity faunas. Climatically, it can be inferred from the marine megabenthic pal˦ontological evidence, thatwarm conditions were present from Early Cambrian until mid-Ordovician times, followed by a much cooler climate that persisted well into the Middle Devonian. The Late Palaeozoic evidence thus indicates cool to cold conditions. In contrast, the Late Permian fossils are consistent with warmer conditions, continuing through Late Jurassic and Cretaceous times along the East African and West African coasts, until the Late Miocene. Within the Gondwanan framework, a Central African region can be envisaged that was subject to non-marine conditions during the entire Phanerozoic Eon. Peripheral to this central African region were marine environments of various ages. The geological history of these peripheral regions was fairly unique. Some features in southern Africa are similar of those found in the Paraná Basin and the Falkland Islands. Most of North Africa from central Senegal to Libya contains a Phanerozoic marine cover extending from the Early Cambrian through to the Carboniferous, characterised by warm water faunas, except for the Ordovician which yields cool-cold water faunas. The Palaeozoic of Arabia, which was an integral part of Africa until the Miocene, has yieldedwarm water fossils.