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内蒙古二连盆地额尔登敖包剖面(相当于伊尔丁曼哈组)的中始新世早期地层中新发现的一件标本显示其属于一个与ameghinornithid相似的种,代表了Ameghinornithidae在亚洲的首个记录。新标本具有外踝半圆形,缺失骨质腱桥,伸肌沟外侧具有大而平的结节,以及其他与ameghinornithid和似ameghinornithid鸟类共有的特征。内蒙古标本与欧洲最古老的ameghinornithids记录大体属同一时代(约48 Ma)。与同时期内蒙古哺乳动物群主要由亚洲类群组成兼有少量与北美有关的绝灭类群不同,这类鸟类中始新世时在北美缺失,而存在于欧洲和亚洲。加上埃及法尤姆早渐新世地层中发现的似ameghinornithid鸟类,这类已经绝灭的鸟类的地理分布似乎比过去所认为的要广泛得多。
A specimen newly discovered in the early Eocene strata of the Erdeng Oboo Section in the Erlian Basin, Inner Mongolia (equivalent to the Ildefjordah) shows that it belongs to a species similar to ameghinornithid, representing the head of Ameghinornithidae in Asia A record. The new specimen has a semilunar lateral malleolus, an absence of a bone bridge, a large, flat nodule outside the extensor ditch, and other features common to ameghinornithid and ameghinornithid birds. The specimens of Inner Mongolia are roughly the same as the oldest record of ameghinornithids in Europe (about 48 Ma). In the same period, the Inner Mongolia mammalian herd is mainly composed of Asian fauna with a few extinct taxa related to North America. These birds were missing in North America during Eocene but existed in Europe and Asia. Together with the ameghinornithid birds found in the Early Oligocene formations of Fayoul, Egypt, the extinct birds appear to be geographically much more extensive than previously thought.