中国中生代的鸟类:介绍及综述(英文)

Mesozoic birds of China:an introduction and review

最近十来年 ,中国辽宁发现的早白垩世的鸟类化石超过了世界上其它任何一个地区。中国的中生代鸟类化石代表了始祖鸟化石之后鸟类历史上第一次显著的分异。它们不仅包括了带有明显恐龙祖先特征的长尾的鸟类 ,而且还包括了许多进步或特化的种类 ,如早白垩世最大的鸟类 ,最原始的反鸟类 ,以及保存最好的、飞行结构和现生鸟类几乎一样的今鸟类。这些早期鸟类在诸如飞行、大小和食性等所反映的演化、形态和生态学特征等方面出现了重大的分异。具有长尾骨骼的原始基干鸟类热河鸟和驰龙类具有的相似性 ,进一步支持了鸟类起源于恐龙的学说。中国发现的早白垩世的鸟类以及树栖的恐龙化石还为鸟类飞行的树栖起源假说提供了十分重要的证据。“恐龙下树”的假说结合了鸟类起源于恐龙的学说和鸟类飞行的树栖起源学说 ,因此也得到了化石证据的支持。由于多种恐龙带有羽毛 ,因此羽毛不一定代表了恒温。

Over the last decade, more Mesozoic birds have been discovered from the Early Cretaceous of Liaoning Province in northeast China than from any other region on earth. Chinese Mesozoic birds represent the earliest significant avian diversification yet known after the oldest known bird Archaeopteryx appeared in the fossil record about 20 million years earlier. They not only include a long-tailed form reminiscent of dinosaurian ancestry but also comprise many other special or derived forms, such as the oldest-known beaked bird, the largest Early Cretaceous bird, the most primitive enantiornithine bird and the best preserved ornithurine bird, with a flight apparatus nearly identical to that of modern birds. Remarkable evolutionary, morphological and ecological differentiation, such as in flight, size and diet, are well documented by the Chinese fossils. The long-tailed, basal bird Jeholornis bears a remarkable resemblance to dromaeosaur dinosaurs, thus providing important clues in support of the dinosaurian origin of birds. Chinese Early Cretaceous birds, as well as arboreal dinosaurs of the same age in China, also provide compelling evidence for the arboreal hypothesis of the origin of avian flight. The ‘Dinosaur-trees-down’ hypothesis, which combines the dinosaurian origin of birds and the arboreal hypothesis of avian flight, is thus well collaborated. Because feathers were present in various dinosaurs, the association of endothermy with feathers becomes purely speculative; endothermy probably did not develop in birds until the Early Cretaceous