环北部湾陆上盆地古近纪鱼类研究

As our fieldwork and research activities progressed in recent years, we have discovered and collected a number of excellent fossil fish specimens from the Paleogene sediments of onshore basins of Beibu Gulf, e.g. cypriniforms, clupeomorpha, and gobiiforms. Especially, cypriniform fishes from this region are highly diversified, including cyprinids, jianghanichthyids (the only fossil family of the order Cypriniformes and only occurred in South China), and cobitids. These fishes are among the oldest cypriniform fossils, which will provide critical information on the origin and evolution of the largest extant freshwater fish order Cypriniformes. The proposed research here will continue to study the systematic paleontology of these cypriniform fossils and their phylogeny. In addition to the traditional fossil preparation and description, high resolution computed tomography will be adopted to assist the morphological and osteological study. The phylogeny analysis will be conducted using data matrix with both morphological and molecular data of extant species. Moreover, the morphology and phylogeny of the Oligocene ellimmichthyiforms and gobiiforms from this region will also be further studied. The former represents the first discovery of ellimmichthyiform from the Oligocene worldwide which is younger than its known fossil records. The latter is the first occurrence of fossil gobiiforms in China. This research project will provide essential information on the taxonomy of the Palaeogene ichthyofauna from the onshore basins around Beibu Gulf, the origin and early diversification of the major groups of the fauna, as well as the early development of the modern fish fauna in southern East Asia.

申请人等在前期工作中发现，环北部湾陆上盆地古近系地层蕴含鲤形目、鲱超目、和鰕虎鱼目鱼类化石。其中鲤形目的鲤科、江汉鱼科（鲤形目唯一的化石科，仅见于我国华南）和鳅科的材料都代表各科最早化石记录，在鲤形目起源和早期演化研究中具有得天独厚的优势和不可替代的作用。本项目拟在此基础上，重点研究本区域鲤形目化石的系统古生物学和系统发育生物学。我们将运用传统的古生物学研究方法，借助高精度CT扫描和同步辐射影像等新技术，重建化石的形态；结合现生类群的形态和分子数据，运用分支系统学原理，分析鲤形目主要类群的系统发育关系和分异时间。其次，我们将深入研究在我国延续到渐新世的鲱超目Ellimmichthyiformes化石、和首次发现于我国的鰕虎鱼目化石。本项目将为阐明环北部湾地区古近纪鱼类组成、鲤形目等重要类群起源与早期演化、以及诠释东亚南部现代鱼类区系的形成提供重要信息。

依托环北部湾地区丰富的古近纪鱼类化石，本项目重点研究区域内鲤形目、鲱超目、鰕虎鱼目化石的系统古生物学和系统发育生物学，为阐明环北部湾地区古近纪鱼类组成、鲤形目等重要类群起源与早期演化、以及诠释东亚南部现代鱼类区系的形成提供重要信息。.本项目主要研究和取得了下列成果：重点梳理了本区域古近纪鱼化石的组成及其时空分布；澄清了三水盆地鲤形目化石的归属，指出三水盆地古新-始新世的江汉鱼科化石是迄今最早的鲤形目化石记录；发现了迄今最早的（始新世）鲤鱼类（Cyprinus-like）化石；指出了北美和亚洲的始新世鲤形目体型存在显著差异，环北部湾区域产出的始新世鲤形目化石对研究鲤形目早期分异和新生代动物地理学具有关键作用；揭示了草鱼类化石可能起源时间和地点，以及草鱼类演化及与之伴随的气候环境变化；重建了埃笠姆鲱目化石的系统发育关系，明确了宁明渐新世鲱类化石的系统位置，提示双棱鲱类(Diplomystus)在该目中具有较长的演化历史和更广泛的空间分布；研究了首次发现于我国的鰕虎鱼目化石，结果表明，沙塘鳢科鱼类最迟在渐新世已栖居于我国南方，这为该科起源于华南渐新世的观点提供了的化石佐证。上述研究结果为阐明环北部湾地区古近纪鱼类组成、鲤形目等重要类群起源与早期演化、以及诠释东亚南部现代鱼类区系的形成提供了重要的化石证据。