Evolution of feathers and colours in birds and dinosaurs

我们建议利用创新的成像和数值系统发育技术以及我们与北京重点研究人员的独特合作，研究恐龙和鸟类羽毛和颜色的进化。鸟类的起源是一个热门话题，吸引了古生物学家、进化论者、生态学家、生理学家和发育生物学家的关注，他们对进化创新（羽毛）、主要多样性（鸟类）和当前生物多样性高的原因感兴趣，这些都是宏观进化的基本方面。我们的研究材料包括来自中国东北热河群的数以万计的鸟类和恐龙化石，这些化石来自早白垩纪（约1.31 - 1.2亿年前）数百米的古湖泊沉积物序列。这些收藏品在20世纪90年代中期引起了轰动，当时第一批有羽毛的恐龙被宣布。到目前为止，几乎没有人对这些羽毛进行过细致的解剖，以揭示它们的秘密。只有通过与中国同事的合作，才能获得这些材料，现在这是可能的。由NERC小额拨款资助的初步工作表明，几乎所有保存完好的羽毛和来自热河群的恐龙和鸟类标本都揭示了羽毛超微结构的惊人细节。特别是，我们已经看到了嵌入在羽毛结构中的两种黑色素体的极好例子，它们看起来与现代羽毛中的那些细胞器一模一样。这一发现令人兴奋的地方在于，这些黑素体负责羽毛的颜色，从白色、灰色和黑色（由真黑素体产生）到红色和黄褐色（由非黑素体产生）。我们的革命性发现将于2010年初发表在《自然》杂志上。我们确定了三个主要问题。羽毛是如何起源的？所有的现代羽毛，从简单的细丝，到绒毛和羽状羽毛，都是一个连续体的一部分，与恐龙的某个单一起源事件有关吗？在现存和灭绝的恐龙中羽毛类型的分布是怎样的？有没有其他的结构，比如现代鸟类和恐龙化石中的固体鬃毛和无刺的羽毛，可能独立于爬行动物的鳞片？最古老的羽毛化石和羽毛状结构是否提供了关于爬行动物鳞片如何变成羽毛的线索？目前争论的焦点是羽毛化石的身份。羽毛的进化与鸟类的高度生物多样性有什么关系？当我们将鸟类与爬行动物的形态学特征（头骨、骨骼和羽毛）的获取映射到古老的系统发育树上时，这些特征的获取顺序如何与多样性和差异的变化以及主要分支的起源相匹配？现代羽毛类型和相关的皮肤结构（如鸟类脚上的鳞片）是启动子和抑制子基因组调控相互作用的结果吗？羽毛类型是如何映射到恐龙和鸟类的主要进化枝上的？它们是否与任何特定的物种进化枝相吻合？羽毛的颜色和图案告诉了我们关于行为进化的什么信息？羽毛形态各方面的获得顺序是否告诉我们羽毛起源的可能原因？此外，这些羽毛的形态、颜色和图案是否能表明交配前的性展示、伪装、警告和啄食顺序等行为的起源？这些化石将从羽毛的性质和获得特征的时间的证据中测试羽毛起源的功能场景。鸟类学家讨论羽毛起源的原因，主要是为了展示、飞行、绝缘、防晒、捕捉昆虫，还是帮助奔跑和跳跃。pennacous羽毛起源于更简单的羽毛类型，这一观察表明羽毛的起源并不是为了飞行。

We propose to investigate the evolution of feathers and colours in dinosaurs and birds, taking advantage of innovative new imaging and numerical phylogenetic techniques as well as our unique collaboration with key researchers in Beijing. The origin of birds is a hot topic that attracts attention from palaeobiologists, evolutionists, ecologists, physiologists and developmental biologists interested in evolutionary innovations (feathers), major diversifications (birds), and reasons for high current biodiversity, all fundamental aspects of macroevolution.Our study materials consist of tens of thousands of fossil birds and dinosaurs from the Jehol Group of north-east China, a sequence of hundreds of metres of ancient lake deposits from the Early Cretaceous, some 131-120 million years ago. These collections created a sensation in the mid 1990s when the first dinosaurs with feathers were announced. Up to now, almost no work has been done on the fine-scale anatomy of those feathers to reveal their secrets. Access to the materials can happen only through collaboration with Chinese colleagues, and this is now possible.Preliminary work, funded by a NERC Small Grant, has shown that nearly all well-preserved feathers and dinosaur and bird specimens from the Jehol Group reveal astonishing details of feather ultrastructure. In particular, we have seen excellent examples of both kinds of melanosomes embedded within the feather structure, and looking exactly like those organelles in modern feathers. The exciting aspect of this discovery is that these melanosomes are responsible for feather colours, ranging from white, grey, and black (produced by eumelanosomes) to reds and yellowish browns (phaeomelanosomes). Our revolutionary discovery will be published in Nature early in 2010.We identify three main questions.1. How did feathers originate? Are all modern feathers, from simple filaments, through downy and pennaceous feathers, part of a continuum that relate to a single origin event somewhere among Dinosauria? What is the distribution of feather types across Dinosauria living and extinct? Are there other structures, such as solid bristles and barbless quills among modern birds, and among fossil Dinosauria, that might have originated independently from reptilian scales? Do the oldest fossil feathers and feather-like structures provide any clues about how a reptilian scale became a feather? Current debates concern the identity of fossil feathers.2. How did feather evolution relate to the high biodiversity of birds? As we map the acquisition of the morphological characters (skull, skeleton and feathers) that differentiate birds from reptiles onto dated phylogenetic trees, how does the sequence of acquisition of those features match changes in diversity and disparity, and the origin of major clades? Are modern feather types, and related dermal structures (e.g. the scales on the feet of birds), the result of an interplay in genomic regulation of promoters and inhibitors? How do feather types map onto major clades among dinosaurs and birds, and do these coincide with any particularly speciose clades?3. What do feather colours and patterns tell us about the evolution of behaviour? Does the order of acquisition of aspects of feather morphology tell us anything about possible reasons for the origin of feathers? Further, can these feather morphologies, colours, and patterns indicate the point of origin of behaviours such as pre-mating sexual display, camouflage, warning, and pecking order? The fossils will test functional scenarios for the origin of feathers from evidence on the nature and timing of acquisition of characters. Ornithologists discuss reasons for the origin of feathers, whether primarily for display, flight, insulation, sunscreens, insect catching, or assisting running and jumping. The observation that pennaceous feathers originated after simpler feather types indicates that feathers did not originate for flight.