Major events of Paleogene mammal radiation in China

AbstractOn the basis of mammalian biostratigraphical study, the Paleogene was subdivided into 11 land mammal ages in China: the Paleocene Shanghuan, Nongshanian and Gashatan; the Eocene Lingchan, Arshantan, Irdinmanhan, Sharamurunian, Naduan and Ulangochuan; and the Oligocene Ulantatalian and Tabenbulukian. Biostratigraphical correlation with North American Land Mammal Ages, plus some palaeomagnetic, isotopic and radiometric results, established the indirect connection with the international time scale. Under this biochronological framework, the compositional change of mammalian faunas and the evolution of major groups are discussed. Three stages are recognized in the Paleogene mammalian radiation: (1) the Paleocene flourishing of archaic groups, (2) the Eocene rising and development of modern major groups and (3) the Oligocene faunal reorganization. During the Paleocene, the mammalian radiation was dominated by the archaic groups and the faunas showed apparent endemism. The radiation was characterized by faunal turnovers due to the flourishing of different families in archaic groups. During this period, ancestral forms of modern glires emerged and the first Rodentiaformes appeared in the late Late Paleocene. Such faunal changes corresponded to the successive rise of temperature after the transition from the Mesozoic to the Cenozoic. The Initial Eocene Thermal Maximum resulted in a significant decrease of the archaic groups and the faunal composition became more similar to that of modern ones. At the beginning of the Eocene, Artiodactyla and Euprimates appeared and Rodentia and Perissodactyla began to differentiate. During the Eocene, Mixodontia, Arctostylopidae, Dinocerata, Pantodonta, Tillodontia and Creodonta disappeared in succession. Perissodactyla became the dominant group in the faunas. The faunal turnovers were characterized by the alteration of dominant families due to the appearance, differentiation and flourishing of families in modern orders. The severe cooling events at the Eocene–Oligocene transition resulted in the development of open grassland, that further contributed to the great mammalian faunal turnover. The perissodactyl‐dominant Eocene faunas were replaced by the rodent/lagomorph‐dominant Oligocene faunas. The appearance and radiation of hypsodont mammal groups characterized the mammalian evolution in the Oligocene. Copyright © 2007 John Wiley & Sons, Ltd.