The Mwesia Beds of northern Malawi in relation to the Tanganyika Problem

Abstract

Abstract In this paper, we trace the saga of the rocks and fossils discovered along Stevenson Road, northern Malawi. Fish and bivalves discovered along the road were proclaimed the first fossils of Central Africa. In the late nineteenth and early twentieth centuries, they became a large part of the ‘Tanganyika Problem’, the notion of whether a Jurassic incursion of the sea left fossils in what is now Malawi and relict marine invertebrates in Lake Tanganyika. Later studies clarified both the geology and zoology of the region, but no more informative fossils were found in Malawi until 2016 when a specimen of Eunotosaurus was discovered by a herdsman in the original nineteenth century fossil locality. He presented the fossil to the Cultural and Museum Centre Karonga, the public face of geoheritage in Malawi. That specimen constrains the upper age limit of the site to approximately 259 Ma (Late Permian). The Tanganyika Problem is now largely of historical interest, yet in a more current multidisciplinary context – the timing and mechanisms of the evolutionary transition of clades from the marine realm into freshwater biomes open new questions about historical biogeography in a geological context.