中文摘要：

脊椎动物颚的起源被考察了基于分子，发展并且 paleontological 证据。在发展遗传的进展积累了建议颚进化的 heterotopy 理论，即颚通过间充组织上皮的相互作用的 heterotopic 移动作为新奇演变。根据这个理论， nasohypophyseal 建筑群的分离是为颚的起源的一个基本前提，自从在圆口动物头开发的 nasohypophyseal placode 的中部的位置预防 neural-crest-derived craniofacial ectomesenchyme 的前面的生长。diplorhiny 的起源上的这分离的潜在的影响也从分子的观点被讨论。因此远，我们 galeaspids，从中国的一个 435-370-million-year-old ostracoderm 组和北越南的头部的解剖上的学习，为在脊椎动物发展史复杂的 nasohypophyseal 的分离提供了最早的石块证据。用同步加速器放射 X 光检查断层摄影术，我们进一步显示出 trabeculae 的一些衍生物结构(例如 orbitonasal 薄板，筛骨的板) 在无颚的 galeaspids，它在颚的进化起源前提供新卓见进脊椎动物头的重组。这些解剖观察基于新技术加亮 galeaspids 是的可能性在许多尊重，一个更好的代理比为重建的 osteostracans 脑壳的喙的部分的 pre-gnathostome 条件。galeaspids 的头部的解剖揭示特别地与 gnathostomes 分享的很多个导出的人物。这提起 galeaspids 可能是 jawed 脊椎动物的最近无颚的亲戚的潜在的可能性。我们的学习提供在发展基于生物学的模型和石块证据之间的交叉的一个吸引人的例子。

英文摘要：

The origin of the vertebrate jaw has been reviewed based on the molecular, developmental and paleontological evidences. Ad- vances in developmental genetics have accumulated to propose the heterotopy theory of jaw evolution, i.e. the jaw evolved as a novelty through a heterotopic shift of mesenchyme-epithelial interaction. According to this theory, the disassociation of the naso- hypophyseal complex is a fundamental prerequisite for the origin of the jaw, since the median position of the nasohypophyseal placode in cyclostome head development precludes the forward growth of the neural-crest-derived craniofacial ectomesenchyme. The potential impacts of this disassociation on the origin of the diplorhiny are also discussed from the molecular perspectives. Thus far, our study on the cranial anatomy of galeaspids, a 435-370-million-year-old ＇ostracoderm＇ group from China and north- ern Vietnam, has provided the earliest fossil evidence for the disassociation of nasohypophyseal complex in vertebrate phylogeny. Using Synchrotron Radiation X-ray Tomography, we further show some derivative structures of the trabeculae （e.g. orbitonasal lamina, ethmoid plate） in jawless galeaspids, which provide new insights into the reorganization of the vertebrate head before the evolutionary origin of the jaw. These anatomical observations based on new techniques highlight the possibility that galeaspids are, in many respects, a better proxy than osteostracans for reconstructing the pre-gnathostome condition of the rostral part of the braincase. The cranial anatomy of galeaspids reveals a number of derived characters uniquely shared with gnathostomes. This raises the potential possibility that galeaspids might be the closest jawless relatives of jawed vertebrates. Our study provides an intriguing example of intersection between developmental biology-based model and fossil evidence.