中国晚更新世猛犸象(Mammuthus)扩散事件的探讨

ON THE DISPERSAL EVENTS OF MAMMUTHUS DURING THE LATE LATE PLEISTOCENE

大型哺乳动物真猛犸象在晚更新世时曾广泛分布北半球辽阔的地区。据最近的研究表明，在我国它曾覆盖了从北纬55°到北纬35°的广大区域。已发现的众多猛犸象化石地点中，有不少已作过详细的同位素年代测定。从生物地层学和同位素年代学的角度，纵观真猛犸象从极地侵入我国境内及其繁盛衰亡的演变史，不难看出真猛犸象在我国北方晚更新世晚期曾有过两次比较集中的活动高潮，并每次都伴随有明显的向南迁徙。它的第一次南迁大致发生在距今3．4－2．6万年前（或可能略早），策二次南迁大致发生在距今2．3－1．2万年前。真猛犸象的这两次南迁活动与本次冰期两次较明显的冷暖交替的小气候波动在时间上大体吻合。

Two late Late Pleistocene dispersal events of Mammuthus were recognized fromnorthem China. The first occurred at the oxygen isotope Stage 4 (about 35000 yearsago), in which Mammuthus reached to N44°from Siberia. The second occurred at theoxygen isotope Stage 2 (about 23000-12000 years ago)- During this periodMammuthus migrated from N44°to about N35°, indicahng that Mammuthusgeographiclly atrived in places that were much more southern than those in the periodof the oxygen isotope Stage 4. Fossil Mammuthus known from northern China alsosuggests that the sea floor of the Recent Yellow Sea was a part of the continent (notcovered by sea water) at Stage 2 because the sea level was much lower than that oftoday. It was also probable that Mammuthus might have migrated through the drainedfloor of the Yellow Sea and reached to Shandong Peninsula, and that the climate ofStage 2 was much colder than that of Stage 4.