摘要
灭绝事件对古生物地理格局的影响已引起关注,近期研究表明奥陶纪末大灭绝事件后多样性显著高于传统认识,而全球该时期腕足动物的古生物地理分布情况尚未见报道。本文基于已发表的和最新的资料及所掌握新数据的整理,建立全球腕足动物志留纪初鲁丹(Rhuddanian)早期(残存期)13个产地72属137个出现信息(occurrence)和鲁丹晚期(复苏早期)26个产地91属272个出现信息的数据集。同时,运用聚类分析(CA)和非度量性多元标度变换(NMDS),对奥陶纪末大灭绝后残存期及复苏早期腕足动物进行定量古生物地理研究,发现残存期及复苏早期腕足动物具有沿纬度分带倾向。对鲁丹早、晚期腕足动物数据的频率分析表明,灭绝前大多数世界性分子(cosmopolitan taxa)在灭绝后收缩其分布范围,甚至局限于一个产地或古板块以躲避灾难,待环境好转,腕足动物多样性增高的同时,更多分子扩散其分布,显示"复苏"的迹象。通过对古生物地理数据频率的分析,文章讨论了6个相似性测度(si milarity measure),并对其适用性与待分析数据结构的关系提出初步认识。建议在相关研究中使用聚类分析的同时辅以其它统计手段(如NMDS),从而使分析结果更加客观可信。
Extinction event may profoundly disturb palaeobiogeographic patterns.There have been few palaeobiogeographic studies of the particular survival-recovery interval after the Late Ordovician mass extinction.Here we analyse global brachiopod occurrences,based on the revision of published information,including new material of brachiopods of South China, for the early and late Rhuddanian,the basal stage of the Silurian immediately following the end Ordovician mass extinction.The dataset consists of 137 occurrences,72 genera,and 13 localities in the early Rhuddanian（survival interval）, and 272 occurrences,91 genera,and 26 localities in the late Rhuddanian（early recovery interval）.The data are analysed using Cluster Analysis,Nonmetric Multidimensional Scaling and Minimum Spanning Tree methods using the Yule＇s Y coefficient and the RC coefficient（probabilistic index of similarity）.The results display palaeolatitudinal distribution patterns for brachiopod survival and recovery.Frequency analysis of the data indicates that the cosmopolitan taxa before the mass extinction showed a decrease in distributions of brachiopods in the survival interval,and expanded temporarily in the recovery interval.Furthermore,discussion on six similarity measures by data frequency analysis indicates that there exists a relationship between the data structure and the applicability of particular similarity measures.We suggest that Cluster Analysis is supplemented by using other statistic methods（e.g.NMDS） in palaeobiogeographic studies to improve objectivity and accuracy.
出处
《古生物学报》
CAS
CSCD
北大核心
2011年第3期304-320,共17页
Acta Palaeontologica Sinica
基金
国家自然科学基金青年基金(41002001)
代古生物学和地层学国家重点实验室自主选题项目(20081103)
Geobiodiversity Database项目联合资助
关键词
相似性测度
大灭绝
残存
复苏
腕足动物
古生物地理
鲁丹期
Similarity measures
mass extinction
survival
recovery
brachiopods
palaeobiogeogrpahy
Rhuddanian
