云南昭通早泥盆世布拉格期肉鳍鱼类形态学与系统学研究

As a key gnathostome lineage which gave rise to all the land vertebrates directly, the evolution of sarcopterygians (coelacanths, lungfishes, land vertebrates and their closest extinct fish relatives) has long been a spotlight issue in the study of early vertebrates. Recent significant fossil sarcopterygians from the Early Devonian of China have established the paleontological importance of China as a center of origin and diversification for sarcopterygians. In particular, a large number of Early Devonian sarcopterygian fossils have been discovered recently in Zhaotong, Yunnan Province. These fossil materials represent a wide selection of major sarcopterygian groups, filling the gaps in fossil records of the early evolutionary history of these groups. The project will be performed using conventional high-resolution CT scanning (HRCT), as well as absorption-based synchrotron microtomography (SR-μCT) and computerized three-dimensional reconstruction. These innovative methods help to exploit the abundance and the significance of these primitive sarcopterygian fossil materials, especially the information provided by the exquisitely preserved cranial morphological details. The comparative anatomy studies on the major sarcopterygian groups will help us gaining a profound understanding of the acquisition sequence of sarcopterygian endocranial characters in their early evolutionary history. Moreover, combining latest data from both molecular and developmental biology, the project aims to provide new solid evidences and new hypotheses for several other important issues in the study of early vertebrates, including the evolutionary pattern of the origin and early diversification of sarcopterygian groups; the sequence of key character acquisitions in the fish-tetrapod transition; and the phylogenetic relationship between sarcopterygians and other major gnathostome groups.

作为探讨四足动物起源的最关键类群，肉鳍鱼类（包括空棘鱼、肺鱼和陆地脊椎动物以及它们已经灭绝的鱼类近亲）的起源与演化一直是生物学、古脊椎动物学研究中的热点话题。近年来中国发现的一系列珍稀的早期肉鳍鱼类化石，使我国成为探讨肉鳍鱼类起源与早期演化的中心。其中，在云南昭通早泥盆世布拉格期发现的大量肉鳍鱼类化石，涵盖了肉鳍鱼类的主要类群，填补了肉鳍鱼类各类群早期化石记录的空白。本项目拟立足我国得天独厚的化石资源优势，应用高精度断层扫描、同步辐射X 射线断层扫描以及计算机三维虚拟重建等目前最先进的技术手段，聚焦肉鳍鱼类主要类群早期演化阶段脑颅重要特征的变化，综合开展对早期肉鳍鱼类各类群比较解剖学研究。同时结合分子和发育生物学最新资料，为解决早期肉鳍鱼类起源和辐射演化、肉鳍鱼类"从水到陆"过程中重要特征的获得序列和脑颅关键特征的演化、以及肉鳍鱼类与其它有颌类间系统发育关系提供更有说服力的化石证据或假说。

本项目立足我国得天独厚的早期脊椎动物化石，在进一步野外发掘的基础上，通过对新发现的和已有的早期肉鳍鱼类所做的细致的形态学与比较解剖学工作，以分支系统学理论为基础，并注意结合分子系统学的相关资料，就肉鳍鱼类的起源与早期演化、四足形动物的演化关系以及四足动物的起源等国际学术界高度关注的课题进行了深入的研究与探讨，并取得了一些突破性进展，尤其在早期脊椎动物的特征演化序列、早期肉鳍鱼类演化、硬骨鱼类的起源与早期演化等方面取得了一系列较有国际影响力的科研成果。项目结合全球相关化石资料、利用高精度CT、同步辐射相衬成像和计算机重建、三维打印等技术手段，聚焦早期硬骨鱼类脑颅的特征演化，综合开展有颌类各大类群脑颅形态的比较解剖学工作，为深刻理解硬骨鱼类脑颅及中枢神经系统在志留纪-早泥盆世这一关键时期的演化，早期硬骨鱼类在感觉、运动等方面的适应提供关键证据。