化石记录的再评估

NEW ASSESSMENT OF THE FOSSIL RECORDS

分子生物学和分支系统学的发展以及化石记录自身的局限性使得古生物地层资料在生物演化研究中的地位遭到质疑。连续的化石记录的发现肯定了化石分析的意义 ,数据库的建立与定量分析方法的应用为古生物学的研究增添了新生力量。

For a long time, fossil record is used as a literal source of data on the history of the diversification of life and of mass extinctions without applying any correction factors for possible time-related bias. Its status has recently been questioned by molecular-clock based studies and cladistics. Molecular clocks have an advantage over fossil clocks in counting mutations at the actual time of divergence. Cladistics is based on character information intrinsic to the taxa while the stratigraphy on the fossil sequence extrinsic to those taxa. However, even those two methods have their own disadvantages. Fortunately, the ideal continuous fossil records do exist, and are invaluable for unravelling the paths of evolution. The fossil record is usually in complete for all groups at all times and in all places. Whatever the quality of the fossil record it must contain information about time of a species' genesis and extinction. We should not ignore this information but rather find ways to use it properly. The database could provide a general concept for the studied subject with the previous results being reviewed systematically. The statistic analyses, including the confidence and likelihood approaches, have been proved useful in assessing the incompleteness of the fossil record. These two methods open a new window for the development of stratigraphy.