曾经在国际古生物界引起轩然大波的拼接化石"古盗鸟"之谜终于被解开,这是在最新一期的英国《自然》杂志发表的题为《古盗鸟的另一半》文章所得出的结论。文章介绍了中国科学院古脊椎动物与古人类研究所古鸟类学者周忠和、张...曾经在国际古生物界引起轩然大波的拼接化石"古盗鸟"之谜终于被解开,这是在最新一期的英国《自然》杂志发表的题为《古盗鸟的另一半》文章所得出的结论。文章介绍了中国科学院古脊椎动物与古人类研究所古鸟类学者周忠和、张福成和美国学者 Julia Clarke 对"古盗鸟"化石的鸟类部分进行了研究,认为它属于已经发表的一种十分进步的食鱼的鸟类——马氏燕鸟。他们认为,曾经被误认为是恐龙和鸟类缺失环节的"古盗鸟"假化石,实际上是由属于驰龙类的小盗龙的尾巴与一个几乎完整的燕鸟的骨架拼接而成的。至此,令人注目的"古盗鸟"之谜基本被解开。"古盗鸟"的故事有了一个完整的收尾。"古盗鸟"展开更多
One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in specie...One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in species that cross such barriers, and are thought to have evolved in response to seasonal variation in prevailing wind direction. We tested the hypothesis that migration routes vary seasonally with respect to the Gulf of Mexico in the tree swallow Tachycineta bicolor using solar geolocators attached and retrieved at 4 breeding sites in central North America. We found that 100 % of birds （n = 10） made a trans-Gulf flight of 〉850 km from Louisiana south to their wintering grounds in the Yucatan Peninsula in 12-36 hours, achieving minimum ground speeds as high as 32 m/s. Although most days during autumn migration were characterized by unfavorable headwinds blowing to the northwest, migration over the Gulf mostly occurred on days with strong winds blowing to the south. In contrast, in 8 of 9 （88 %） birds on spring migration returned from the wintering grounds towards Louisiana following a clockwise loop pat- tern flying over land to the west around the Gulf. During this spring period there were few days with prevailing winds from the south to assist northward migration. Results suggest that, despite being up to three times further （ca. 2,700 kin）, a coastal circum-Gulf spring migration represents the less risky route when wind conditions are not favorable. These findings also help to resolve a long-standing dispute in the literature concerning migration patterns between the US Gulf coast and Mexico, and provide insight into the factors shaping migration strategies of small songbirds migrating across large bodies of water [Current Zoology 60（5）： 653-559, 2014].展开更多
文摘曾经在国际古生物界引起轩然大波的拼接化石"古盗鸟"之谜终于被解开,这是在最新一期的英国《自然》杂志发表的题为《古盗鸟的另一半》文章所得出的结论。文章介绍了中国科学院古脊椎动物与古人类研究所古鸟类学者周忠和、张福成和美国学者 Julia Clarke 对"古盗鸟"化石的鸟类部分进行了研究,认为它属于已经发表的一种十分进步的食鱼的鸟类——马氏燕鸟。他们认为,曾经被误认为是恐龙和鸟类缺失环节的"古盗鸟"假化石,实际上是由属于驰龙类的小盗龙的尾巴与一个几乎完整的燕鸟的骨架拼接而成的。至此,令人注目的"古盗鸟"之谜基本被解开。"古盗鸟"的故事有了一个完整的收尾。"古盗鸟"
文摘One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in species that cross such barriers, and are thought to have evolved in response to seasonal variation in prevailing wind direction. We tested the hypothesis that migration routes vary seasonally with respect to the Gulf of Mexico in the tree swallow Tachycineta bicolor using solar geolocators attached and retrieved at 4 breeding sites in central North America. We found that 100 % of birds （n = 10） made a trans-Gulf flight of 〉850 km from Louisiana south to their wintering grounds in the Yucatan Peninsula in 12-36 hours, achieving minimum ground speeds as high as 32 m/s. Although most days during autumn migration were characterized by unfavorable headwinds blowing to the northwest, migration over the Gulf mostly occurred on days with strong winds blowing to the south. In contrast, in 8 of 9 （88 %） birds on spring migration returned from the wintering grounds towards Louisiana following a clockwise loop pat- tern flying over land to the west around the Gulf. During this spring period there were few days with prevailing winds from the south to assist northward migration. Results suggest that, despite being up to three times further （ca. 2,700 kin）, a coastal circum-Gulf spring migration represents the less risky route when wind conditions are not favorable. These findings also help to resolve a long-standing dispute in the literature concerning migration patterns between the US Gulf coast and Mexico, and provide insight into the factors shaping migration strategies of small songbirds migrating across large bodies of water [Current Zoology 60（5）： 653-559, 2014].
