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The consensus view among geologists is that the Lanzhou Basin sequence of sediments contains the Oligocene/Miocene boundary, but where this occurs is unknown. Indeed, this is the crux of the issues concerning mid-Tertiary paleontology in Asia: what fauna corresponds with this time? What turnover events or distinctive taxa signal the beginning of the Miocene epoch? Once known, this will be of broad usefulness because vertebrate-bearing deposits are widespread in Asia and can be used to date basin sediments. Lanzhou and other basins permit a means of correlating to the time scale by using fauna and paleomagnetic data locally, and ultimately radiometric data from distant localities, to develop a precise biochronology. Herein, we summarize faunal constraints, primarily those of small mammal taxa, on correlation of the Lanzhou magnetozone sequence to the magnetic time scale. We conclude that the lower part of the Xianshuihe Formation contains theOligocene/Miocene boundary, and that the top of the formation, both in the south and north parts of the basin, is middle Miocene in age. Rodents from lower white sand units of the Xianshuihe Formation, correlate to the Xiejia assemblage of the Xining Basin, Qinghai Province, and are early, but not earliest, Miocene age. The implication for rodent faunas of the epoch boundary is that they retained a mainly "Oligocene" composition, and that other presumed late Oligocene assemblages may be, in fact, early Miocene in age. The Lanzhou appearance of Proboscidea is 19-18 Ma, as expected., Engineering and Applied Sciences

A partial skeleton was recovered from middle Miocene Muruyur sediments near Kipsaramon in the Tugen Hills, Baringo District, Kenya. The specimen, representing much of the upper skeleton, comes from locality BPRP#122 dated between 15·58 Ma and 15·36 Ma. It is referable to the middle Miocene hominoid taxon Equatorius africanus. Preliminary descriptions of the partial skeleton are provided. While the anatomy of the wrist, thorax and hindlimb in Equatorius is similar to that of Afropithecus and Proconsul, the morphology of the new skeleton confirms earlier interpretations of greater terrestriality in Equatorius. [Copyright &y& Elsevier]