The Malvinokaffric Realm in the Early-Middle Devonian of South Africa

Abstract

The Devonian palaeontological record of South Africa is essential in understanding plant and animal evolution as well as global palaeobiogeography and palaeoecology at high subpolar-polar (60–90°) southern palaeolatitudes. As early as the mid-nineteenth century, fossils, most notably those of marine invertebrates, from rocks that would later be known as the (? Pragian-Emsian) Rietvlei/Baviaanskloof formations (Table Mountain Group) and the (Emsian-Givetian) Bokkeveld Group have been recognised to be faunally distinct and similar to those found in Emsian-Eifelian (Early-Middle Devonian) successions in Argentina, Antarctica, Bolivia, Brazil, Falkland Islands (Malvinas), Guinea, Guinea-Bissau, Ghana and Senegal. This broad region of endemism in southwestern Gondwana was referred to by many iterations, namely ‘Flabellite Land’, the ‘Austral Province’, ‘Falklandia’ and later by the ‘Malvinocaffrischen Provinz’ or ‘Malvinokaffric Realm’ as is used currently. Many fossils from the Rietvlei/Baviaanskloof formations and the Bokkeveld Group are important in defining the faunal composition of the Malvinokaffric Realm. The Malvinokaffric Realm is noteworthy in that it comprises a low-diversity fauna with high endemism, namely those of terebratulid, strophomenid and spiriferid brachiopods as well as calmoniid and some homalonotiid trilobites. Conulariids, tentaculitids and hyolithids are abundant and reef-building corals are rare whilst stromatoporoid sponges, conodonts, goniatite ammonoids and graptolites are generally absent. Subsequent research suggests that several gastropods, ostracods, palynomorphs, acritarchs, chtitinozoans and gnathostome fish may also be endemic to this region. Palaeoclimatic and palaeomagnetic indicators suggest that the Malvinokaffric Realm was situated at subpolar-polar regions during the Emsian-Eifelian, persisting at cool temperatures. Given the high palaeolatitudes occupied by southwestern Gondwana during the Devonian Period as well as the relatively complete stratigraphic record of this period in South Africa, continued research into the palaeontology, palaeoenvironments, and palaeoecologies of this key Malvinokaffric locality will continue to ever ingrain the importance of Africa in understanding global palaeobiogeography.