基于黑色素的热河生物群鸟类和其他兽脚类恐龙羽毛颜色及功能演化

Melanin-based coloration, for functions as diverse as camouflage, advertisement for mates, aposematism, startling prey, and other non-communication functions like thermoregulation, is a fundamental aspect of the physiology and functional morphology of feathers. However, until recently no available data can offer insight into the early evolution of plumage coloration patterns from the fossil record. The discovery of the melanosomes in fossils record offers an possibility to investigate plumage coloration in a comparative frame. Successfully predicting the first plumage color pattern in the theropod dinosaur, Anchiornis huxleyi, and the first iridescent color in another theropod dinosaur, Microraptor, brings confidence to study the melanin-based color of feathered dinosaur and bird fossils and look into its deep evolutionary history. ..The present proposed research will bring more and more fossil data from feathered dinosaur and bird fossils to study the function and evolution of melanin-based color of these taxa. With aim to identify the patterns of morphological evolution in melanosomes, this research will sample most of the nature groups of both feathered dinosaur and bird fossils. With the skill of TEM and SEM, the data of the melanosomes size, shape, aspect ratio, density, arranged way will be obtained from the featherd taxa. These data will improve the understanding of the morphology evolution of the melanosomes in the phylogeny of the featherd taxa from the Jehol Biota. This reseach will also expand the present data of the melanosomes in the extant birds by sampling more taxa. Canonical discriminant analysis (CDA) on morphological data from melanosomes of differently-colored feathers from living birds will be used to separate several different colors and predict the colour of the feather fossils. With aim to identify the plumage color pattern evolution in theropod dinosaur and birds, the plumage color reconstruction will cover different groups of the feathered dinosaur and bird fossils, even sometimes different individuals of the same taxon to make sure the sexual difference. To identify the function of the plumage color pattern of the theropod dinosaur and bird fossils, this research will also analyze the morphology of the feathers and the habitat of the animals. With the above mentioned groundwork, this project pursues to reveal the melanosome morphology evolution in the phylogeny of theropod dinosaur and bird fossils, their evolutionary pattern of melanin-based coloration and its potential relationship with the evolution of feather morphology.

基于黑色素的鸟类羽毛颜色有展示、温度调节、保护色、惊吓猎物等功能，是鸟类生理与功能形态的基本特征。但是，由于缺乏有效的方法和途径，直至近几年，随着羽毛化石内部黑素体的发现，研究羽毛化石中的颜色才成为可能，从而开辟了古生物学研究的一个最新领域。申请人前期的研究首次恢复了一个恐龙羽毛颜色（近鸟龙），首次在恐龙（小盗龙）身上发现彩虹色泽的结构色。这些成果证明能够通过黑素体研究洞悉羽毛颜色功能演化。.本项目通过对热河动物群兽脚类恐龙和古鸟类不同类群的羽毛超微结构研究，利用扫描电镜和透射电镜，获取黑素体形态学特征。同时，拓展此前建立的现生鸟类黑素体的形态学数据库。进一步完善判别式分析的方法，预测不同类群羽毛颜色。结合兽脚类恐龙和鸟类的系统发育研究结果，揭示兽脚类恐龙和古鸟类羽毛中黑素体形态的演化过程；结合形态功能学的分析，揭示兽脚类恐龙和古鸟类羽毛颜色式样演化模式及其与羽毛形态演化的潜在关系。

羽毛化石内的黑素体的发现，使恐龙羽毛颜色复原成为可能。与鸟类关系很近的晚侏罗世近鸟龙（Anchiornis）颜色、早白垩世小盗龙（Microraptor）羽毛的彩虹色泽结构色先后被复原出。这些颜色复原主要依据现生鸟类中黑素体形态与颜色的对应关系，这种对应关系在兽脚类恐龙演化过程中究竟从哪个节点开始，目前未知。项目组对热河生物群的其他恐龙、古鸟类、翼龙、蜥蜴、乌龟等的皮肤及其衍生物黑素体形态调查显示黑素体形态多样性在手盗龙类内和现生哺乳动物内突然增加，除此之外的其它羊膜类脊椎动物的黑素体形态多样性很低，这与其现生类型的颜色多样性不符合，可能有其它类型的色素参与。黑素体形态多样化现象显示黑皮质素系统在哺乳动物和手盗龙类的趋同演化，这样的变化会同时影响基于黑素体的颜色模式和脊椎动物中的新陈代谢，进而支持手盗龙类内部发生新陈代谢加快的关键生理变化假说，这种生理变化发生在鸟类飞行起源之前。该研究成果在Nature上发表。.项目组同时还对我们还对发现于辽宁建昌九佛堂组的一件反鸟类标本进行了黑素体形态分析，同时尝试进行拉曼光谱分析。研究发现该反鸟类具有长柱形的黑素体，与现生鸟类中产生彩虹色泽结构色的黑素体形态相似，揭示了第一个具有彩虹色泽结构色的反鸟类。同时在拉曼光谱分析中，在化石黑素体的拉曼光谱信号观察到了与现生黑素体相似的光谱信号。为无损检测化石黑素体化学成分提供了一种新的手段。.项目组对一件新的产自河北丰宁的早白垩世孔子鸟类标本进行研究，新的标本保存了非常完整的羽毛印痕。该化石发育一个突出的羽冠，头顶和下颌的羽毛发育色斑；翅膀和尾部羽毛也发育很有规律的色斑。我们采用形态学和化学成分结合的方法，通过对32个区域进行成对取样，一个样品用于扫描电镜分析，另外一个样品用于纤维拉曼光谱分析。从扫描电镜结果中，我们取了代表不同形状的黑素体样品，在这些部位重新取样，用于Tof-Sims分析。在32个样品中，有8个样品的形状多样性很大，形态变化超过了现生鸟类羽毛的变化范围，我们解释为可能存在不同的羽毛叠加在一起的可能。对有效部位的颜色复原显示，孔子鸟的色调是灰色或者黑色。头顶羽冠和翅膀总体是暗色背景下分布的黑色斑点。拉曼光谱分析显示大部分样品都展示了与现生真黑素相似的光谱信号，与降解羽毛的细菌的光谱特征、围岩的特征有明显差别。拉曼光谱没有化石中识别出褐黑素的信号。颜色复原现实该孔子鸟类标本