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Quaternary environmental changes and evolution of large mammals in North China
- Qiu Zhanxiang
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2006, 44(02):
109-132.
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Preparation and publication of GTS 2004 led the discussion on the concept, time duration and rank of the " Quaternary" to a new height. Pending the final ratification, it seems almost certain that its lower boundary is to be lowered to —2. 6 Ma, but its rank as Period or Sub-Era remains to be decided. At any rate, the " Quaternary" will encompass 3 major units: the late Pliocene, Pleistocene and Holocene, which are chiefly based on marine deposits. The " Quaternary" large mammals of North China has been extensively studied for a long time. Now it is advisable to review their evolution in light of the new perspective. Tentative analysis of the available paleoenvironmental data in conjunction with the evolutionary phases of the mammalian faunas shows the following: 1) —2. 6 Ma is certainly a critical period, at least in North Asia, when a number of events concurred. These include the great expansion of the Arctic ice sheet, the beginning of large-scaled loess deposition induced by intensification of monsoon system, and the extinction of large numbers of typical Hipparion fauna by —2. 6 Ma. 2) 2. 6 l. 3 Ma is a period flourished with archaic types of " Quintenary" large mammals. As immigrants from North America, Equus and Megantereon entered Eurasia at the beginning of the period. Large numbers of typical “Quaternary” genera appeared, like Eirictis, Metes, Crocuta, Coelodonta, Eucladoceros, Elaphurus, Leptobos, etc. Climate of this period, especially its later half, was comparatively stable, rather mild in general, as shown in Ding et al. 's Chiloparts. 3) l. 3 —0. 13 Ma is characterized by particular development of Sinomegaceros. Typical Middle Pleistocene species as typified by ZKD fauna appeared, like Canis variabilis, Pachycrocuta sinensis, Megantereon inexpectatus, Dicerorhinus kirchbergensis, etc. A peculiar aspect is the invasion of Oriental elements into the south part of the North China, like Ailuropoda, Stegodon orientalis, Megatapirus, Elaphodus, Capricornis, etc., at the very beginning of this period. Climate of this period was highly variable, with at least 3 cold and one prolonged warm episodes (LIS, L9, L2 and S5 in Chiloparts). Therefore, this period might be further subdivided when in-depth study is carried out in the future. 4) 0. 13 — 0. 011 Ma is characterized by a mixture of survived coldadapted forms with living species. Climate of this period was probably mild. Such a climatic condition might have caused the adaptive radiation of the survived cold-adapted forms, as exemplified by the bizarre-antlered giant deer. 5) 0. 011 Ma Recent is equivalent to Holocene. Its mammalian fauna became modernized, with the final extinction of holdovers of the glacial period exemplified by mammoth and woolly rhinoceros.
We suggest that the above 4 phases be designated from earliest to latest as NCMQ1~ 4. The NCMQ1 —2 boundary does not coincide with that of Plio-Pleistocene (1. 8 Ma), neither with that of Early-Middle Pleistocene (0. 78 Ma). However, such a subdivision is rather close to the subdividions based on mammals currently adopted in North America and Europe. The Blancan-lrvingtonian boundary (in N ALMA) lies at — 1. 35 Ma. The upper boundary of the European Villafranchian lies also between l. 4~ 1. 1 Ma.
