The Miocene fossil beds of Maboko Island, Kenya: Geology, age, taphonomy and palaeontology

A morphotype catalog and paleoenvironmental interpretations of early Miocene fossil leaves from the Hiwegi Formation, Rusinga Island, Lake Victoria, Kenya

“…The presence of KP-13 and KP-14, in combination with the fluvial sedimentary structures at the collection locality (Figure 3.1), strongly suggests this is a floodplain deposit that was periodically flooded or possibly occasionally submerged in standing water. This paleoenvironmental interpretation is consistent with previously documented streamside or riparian vegetation from the R5 and R117 areas (e.g., Andrews and Van Couvering, 1975;Collinson, 1985;Collinson et al, 2009;Retallack et al, 1995), with the discovery of vertebrate fossil elements from aquatic animals in laterally equivalent strata to our fossil leaf site (unpublished data), and with the abundance of aquatic vertebrates ~5-10 m stratigraphically above this fossil leaf deposit (Conrad et al, 2013).…”

“…This leaf size distribution, although based on a relatively small sample size, is most consistent with a forest type environment. This is further corroborated by the lack of grasses in our collection, an essential component of woodland environments (Jacobs, 2004), as well as in all previous paleobotantical studies from Rusinga (Chester, 1957;Andrews and Van Couvering, 1975;Collinson, 1985;Collinson et al, 2009). This evidence suggests that patches of more closed, forested environments may have been important components of Rusinga's paleoecology during this time interval.…”

“…Paleoenvironmental reconstructions from various proxies have yielded contradictory results, with interpretations ranging from tropical rain forest to woodland to a semi-arid climate (Chesters, 1957;Andrews and Van Couvering, 1975;Evans et al, 1981;Collinson, 1985;Thackray, 1994;Retallack et al, 1995;Bestland and Krull, 1999;Forbes et al, 2004;Collinson et al, 2009;Ungar et al, 2012). Many studies have examined data from the entire Hiwegi Formation (e.g., Andrews and Van Couvering, 1975;Evans et al, 1981;Retallack et al, 1995;Forbes et al, 2004;Ungar et al, 2012), which may span >100 kyr (Peppe et al, 2011;McCollum et al, 2012). Hence, these studies likely sampled a mixture of environments from different time periods during the deposition of the Hiwegi Formation.…”

A hoatzin fossil from the middle Miocene of Kenya documents the past occurrence of modern-type Opisthocomiformes in Africa

“…The fossiliferous sites of Maboko Island were interpreted as floodplain deposits (Andrews et al 1981), but more recent evidence from paleosols suggests a diversity of microhabitats, from relatively dry bushland to riparian woodland (Retallack et al 2002). The white clay of bed 5 of Maboko Main, from which the tarsometatarsus stems, is a paleosol type indicative of seasonally waterlogged wooded grassland (Retallack et al 2002).…”

“…This fossil site is well-known for its mammalian fauna, and primate fossils are especially abundant (e.g., Andrews et al 1981, Benefit 1999, Geraads et al 2012. Maboko Island also yields a comparatively rich avifauna, which, however, remains little studied.…”