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Pleistocene, Kenya, forest, snails, palaeoecology, Panga ya Saidi
Abstract:
A Quaternary sequence of subfossil terrestrial molluscs from tropical Kenya is described and discussed. It preserves a remarkably complete fauna of the Indian Ocean coastal forest from the surroundings of Panga ya Saidi cave, a site featuring repeated human occupation extending back at least 78, 000 years. Mollusc diversity, composition, and abundance are very similar to extant faunas of the coastal forest. They vary relatively little over the period studied (chiefly a 50,000-year sequence from MIS 5 to the start of MIS 2) apart from a short-lived decrease in the dominance of “forest-only” species around 45,800 BP. The fauna of the most recently preserved layers (MIS 1) is likewise similar. Most of the 72 snail (and slug) species found are still extant at the coast, including some narrow-range endemics, but 8 species are now more western in their known distribution. The native African status of Kaliella barrakporensis and 2 other snail species with Asian type localities are confirmed, as is the previously disputed occurrence of native Helicoidea at the coast. Two new subfossil species were identified and are described as Maizania meteor sp. n. (Maizaniidae) and Juventigulella saidii sp. n. (Streptaxidae). No major habitat or faunistic shifts are observed, confirming previous evidence for long-term ecological continuity at the site. The data are the first of their kind from coastal East Africa and provide a new independent proxy of the environmental context to the archaeological sequence, as well as a reference point for future studies of terrestrial molluscs in the region.
