摘要
利用ＮｄＹＡＧ 激光ＡｒＡｒ 测年法，对产自辽西北票四合屯尖山沟地区义县组底部孔子鸟和中华鸟龙湖相层中火山凝灰岩中的黑云母单晶做了５０ 多次分析， 得出的同位素年龄值为（１４７ ±１．８） Ｍａ ， 用ＫＡｒ 法测得孔子鸟化石外面的火山包裹层的结果为（１４７．３ ±３ ．３）Ｍａ ，两者年龄时代相当吻合，同为晚侏罗世晚期（ 晚提唐期） ，比德国始祖鸟层的时代略晚，也与孔子鸟特征和美颌龙类———中华鸟龙指示的地质时代吻合。
Recent discoveries of Mesozoic feathered theropod and bird fossils (Liaoningornis, Confuciusornis, Caudipteryx, Protarchaeopteryx and Sinosauropteryx) from the Yixian Formation, Liaoning, NE China have provided an excellent opportunity to examine the long running debate on the hypothesis that birds evolved from dinosaurs, and to reveal the early evolution of feathers. K Ar dating of volcanic ash from the coverage of Confuciusornis Sanctus Hou et al.yields (147.3±3.3)Ma for the age of the fossil.40Ar/39Ar laser single grain dating on individual biotite grains collected from a volcanic bed, about 20 m above the stratigraphic position of the fossil bed, in the lower part of the Yixian Formation yields ages in the range of 136.2～155.4 Ma[mean age of (145.3±4.4) Ma] with an intercept age of (147.1±1.8) Ma. These two ages are in excellent agreement and thus, resolve a controversy regarding age of these fossils. It is now firmly established that the feathered theropods and early birds in NE China lived in the late Jurassic, about the same time period as Archaeopteryx found in Bavaria.
出处
《地球化学》
CAS
CSCD
北大核心
1999年第4期405-409,共5页
Geochimica
基金
国家自然科学基金!(编号:49812020)
中国科学院重大研究基金!(编号:KZ951- B1- 410)
关键词
孔子鸟
晚侏罗世
中华鸟龙
氩40-氩39测年
Confuciusornis
Laser 40Ar/39Ar dating
Late Jurassic
Yixian Formation
Liaoning Province
