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A partial skeleton of a primitive bird, Rahona ostromi, gen. et sp. nov., has been discovered from the Late Cretaceous of Madagascar. This specimen, although exhibiting avian features such as a reversed hallux and ulnar papillae, retains characteristics that indicate a theropod ancestry, including a pubic foot and hyposphene-hypantra vertebral articulations. Rahona has a robust, hyperextendible second digit on the hind foot that terminates in a sicklelike claw, a unique characteristic of the theropod groups Troodontidae and Dromaeosauridae. A phylogenetic analysis places Rahona with Archaeopteryx, making Rahona one of the most primitive birds yet discovered. 相似文献
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A primitive enantiornithine bird and the origin of feathers 总被引:2,自引:0,他引:2
A fossil enantiornithine bird, Protopteryx fengningensis gen. et sp. nov., was collected from the Early Cretaceous Yixian Formation of Northern China. It provides fossil evidence of a triosseal canal in early birds. The manus and the alular digit are long, as in Archaeopteryx and Confuciusornis, but are relatively short in other enantiornithines. The alula or bastard wing is attached to an unreduced alular digit. The two central tail feathers are scalelike without branching. This type of feather may suggest that modern feathers evolved through the following stages: (i) elongated scale, (ii) central shaft, (iii) barbs, and finally (iv) barbules and barbicel. 相似文献
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2016年6月至2017年3月,于旱季与雨季分别开展泸沽湖省级自然保护区鸟类多样性调查,对比不同生境鸟类多样性组成,以期反应泸沽湖退耕还湿的成效。结果表明:泸沽湖现有鸟类120种,隶属15目44科。其中留鸟63种,候鸟46种。基于不同生境鸟类相似性指数,无论是旱季还是雨季,退耕还湿区和林地相似性最高;退耕还湿区在雨季形成了季节性沼泽,但水鸟却仅6种,远低于林鸟;旱季退耕还湿区因水位下降归于旱地,不利于水鸟栖息。泸沽湖实施退耕还湿工程后,目前退耕还湿区对鸟类栖息的服务功能与陆地更为相似,作为湿地的服务功能相对较弱。 相似文献
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东方白鹳(Ciconia ciconia boycina)于每年三月中、下旬迁来黑龙江省兴凯湖自然保护区繁殖。巢筑在沼泽地的柳树上部,用于柳枝搭成,巢径210厘米,巢体高63厘米,距地面高3—4米。4月1日前后交配产卵,隔日产卵1枚,每年产卵4—5枚。孵化期为32天,每天雌雄交替孵化4次。育雏期每3小时左右采食一次。据1987、1988年人工饲养的幼雏各2只观察,幼雏生长发育迅速,日采食量350克(6日令)—2000克(50日令)。3日令可击喙发声,6日令长出飞羽芽,17日令长出正羽,50日令能站立,60日令自由活动,65日令试飞,70日令自由飞翔。跗跖长、体长、翼长分别于50、60、70日令前增长显著,之后便停止增长。体重增倍的间隔日期依次是2.5、3、4、6、20天,60日令后增长缓慢以致停止增加。喙长则持续而缓慢地增长。 相似文献
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对三个快羽系、三个慢羽系及其九个杂交组合共1440只雏鸡在42日龄内的羽速羽型特征作了研究。结果表明:1、出壳时的羽型可根据主翼羽与覆主翼羽的绝对差度分为六型。2、在42日龄内,三个快羽系的羽型特征较一致;而三个慢羽系的羽型却有较大的差异。3、亲本对杂交鸡的羽型影响在品系间有差异。4、在42日龄内的不同阶段,羽速(即快、慢羽)的鉴别要按不同部位的羽型特征的差异来进行。 相似文献
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The fossil record of early feathers has relied on carbonized compressions that lack fine structural detail. Specimens in amber are preserved in greater detail, but they are rare. Late Cretaceous coal-rich strata from western Canada provide the richest and most diverse Mesozoic feather assemblage yet reported from amber. The fossils include primitive structures closely matching the protofeathers of nonavian dinosaurs, offering new insights into their structure and function. Additional derived morphologies confirm that plumage specialized for flight and underwater diving had evolved in Late Cretaceous birds. Because amber preserves feather structure and pigmentation in unmatched detail, these fossils provide novel insights regarding feather evolution. 相似文献
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Late Jurassic and Early Cretaceous birds from northeastern China, including many complete skeletons of Confuciusornis, provide evidence for a fundamental dichotomy in the class Aves that may antedate the temporal occurrence of the Late Jurassic Archaeopteryx. The abundance of Confuciusornis may provide evidence of avian social behavior. Jurassic skeletal remains of an ornithurine bird lend further support to the idea of an early separation of the line that gave rise to modern birds. Chaoyangia, an ornithurine bird from the Early Cretaceous of China, has premaxillary teeth. 相似文献
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落叶阔叶林中初级洞巢鸟在群落组织结构形成中的作用 总被引:4,自引:0,他引:4
在落叶阔叶林中对初级洞巢鸟在群落组织结构形成中的作用做了5a的研究。结果表明,在39.8hm2样地中共有17种鸟类组成,年间鸟种多样性相似。初级洞巢鸟5a中共啄洞108个,每年的递增率为29.4%,被次级洞巢鸟总利用率为58.8%~84.6%,其多度和丰富度都在50%以上,在鸟类群落组织结构形成中的贡献率为12.5%~42.9%。因此可以认为初级洞巢鸟是落叶阔叶林中鸟类群落组织结构形成中的“关键类群”。 相似文献
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2007年10月至2008年10月,采用样地法和样线法对南昌市5个样点的鸟类进行了野外调查和监测,共记录到鸟类144种,隶属14目49科.其中留鸟57种,候鸟(包括夏候鸟、冬候鸟和旅鸟)87种;古北界种类60种,东洋界种类64种,广布种20种,分别占本区鸟类种数的41.7%、44.4%、13.9%;南昌市鸟类群落物种S... 相似文献
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Exclosure experiments have demonstrated the effects of bird predation on arthropods. In a Mexican coffee plantation, we excluded foliage-gleaning bird and bat predators from coffee plants. Effects of bats and birds were additive. In the dry season, birds reduced arthropods in coffee plants by 30%; birds and bats together reduced arthropods by 46%. In the wet season, bats reduced arthropods by 84%, whereas birds reduced them by only 58%. We conclude that previous "bird" exclosure experiments may have systematically underestimated the effects of bats. 相似文献
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崇明岛稻蟹种养池塘的主要鸟害及生态防鸟技术的初步研究 总被引:1,自引:1,他引:0
稻蟹综合种养是崇明地区主要的农业生产方式之一,崇明生态岛是亚太地区候鸟南北迁徙的重要停歇地,但丰富的鸟类资源也对稻蟹种养造成了一定的不利影响。本研究首先初步调查了崇明稻蟹种养区域的主要鸟类组成,比较了不同稻蟹种养模式下主要鸟害种类和发生时间,在此基础上进一步比较了两种生态防鸟方式的防鸟效果和投入产出情况。结果表明:(1)崇明稻蟹池塘的常见鸟类有13种,其中鹭类种类最多,为6种;(2)纯养蟹池塘主要危害种类为鹭类,危害时间主要为秋冬季,稻蟹共作池塘的主要危害鸟类为鹭类、麻雀和喜鹊等,麻雀和喜鹊的危害时间主要为水稻播种期、灌浆期和成熟期;(3)尼龙线防护成本较低,适合于纯养蟹池塘,该方法一次性投入为1 443元/hm2;线网防护成本较高,一次性投入高达5 096元/hm2,考虑折旧后的成本约为1 999元/hm2,该方法适合于稻蟹共生池塘,防鸟效果较好。因此,对稻蟹综合种养而言,采用线网结合的防护方式,辅以稻草人等视觉驱鸟方法,具有较好的经济效益和生态效益。 相似文献
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Norell MA Clark JM Demberelyin D Rhinchen B Chiappe LM Davidson AR McKenna MC Altangerel P Novacek MJ 《Science (New York, N.Y.)》1994,266(5186):779-782
An embryonic skeleton of a nonavian theropod dinosaur was found preserved in an egg from Upper Cretaceous rocks in the Gobi Desert of Mongolia. Cranial features identify the embryo as a member of Oviraptoridae. Two embryo-sized skulls of dromaeosaurids, similar to that of Velociraptor, were also recovered in the nest. The eggshell microstructure is similar to that of ratite birds and is of a type common in the Djadokhta Formation at the Flaming Cliffs (Bayn Dzak). Discovery of a nest of such eggs at the Flaming Cliffs in 1923, beneath the Oviraptor philoceratops holotype, suggests that this dinosaur may have been a brooding adult. 相似文献
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阮籍和嵇康诗歌中鸟的意象 总被引:1,自引:0,他引:1
孔荣 《信阳农业高等专科学校学报》2009,19(3):84-86
阮籍和嵇康诗歌中有许多鸟的意象,不仅数量大、种类繁多,而且内涵丰富。二人的诗歌中,鸟的意象的运用有很多不同,诗歌中塑造的形象和蕴藏的内涵也有不同点。这些不同是由于诗人的思想和艺术风格不同而造成的。阮籍和嵇康对鸟这个意象的不同的创造丰富了鸟这个意象的内涵,这正是诗歌文人化在正始时期的具体表现之一。 相似文献
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按《世界鸟类分类及分布名录》的分类体系,调查统计四川省雷波县豆沙溪沟流域水电规划区鸟类的组成、区系状况、居留性质、珍稀鸟类以及分布情况.对该区域进行调查统计得鸟类11目31科87种,其中留鸟60种、夏候鸟20种、冬候鸟3种及旅鸟4种,国家Ⅱ级保护鸟类8种;繁殖鸟类占该区域鸟类的91.95%,成为该区域鸟类组成中的主要优势类群,该区域内植被划分为亚高山针阔混交林、常绿与落叶阔叶混交林、低山灌草丛、农耕地植被及河流湿地5个类型,繁殖鸟类在各植被类型中仍然占据主要的成分. 相似文献
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