茅口期■类动物的灭绝过程——灭绝选择性与物种个体大小关系的验证  

STUDY ON EXTINCTION PROCESS OF MAOKOUAN FUSULINACEAN FAUNA——A TEST FOR EXTINCTION SELECTIVITY RELATED TO BODY SIZE

作　　者：杨湘宁[1] 刘家润[1] 施贵军[1] 周建平[2] 

机构地区：[1]南京大学地球科学系,南京210093 [2]中国科学院南京地质古生物研究所,南京210008

出　　处：《古生物学报》2001年第4期463-470,共8页Acta Palaeontologica Sinica

基　　金：国家自然科学基金项目 (No.40 0 72 0 0 8);国家重点基础研究发展规划项目 (G2 0 0 0 0 7770 0 )资助

摘　　要：对茅口期类动物群灭绝过程的分析揭示 ,若将类物种按壳体大小分为两类 ,从动物群物种分异度、物种净增速率的变化来看 ,大个体 (壳长 >6mm)物种与小个体 (壳长≤ 6mm)物种的灭绝过程并无明显的区别。根据壳壁等特征 ,茅口期类可分为南京类、希瓦格类、费伯克类和新希瓦格类 4个主要类群 ,各主要类群及其壳体大小不同的物种灭绝过程有明显的差异。在灭绝事件早期 ,各类群及其壳体大小不同的两类物种所受的影响有所不同。在早期的灭绝中 ,南京类、新希瓦格类、希瓦格类中壳长 >6mm和费伯克类中壳长≤ 6mm的物种显著减少 ,而希瓦格类中壳长≤ 6mm以及费伯克类中壳长 >6mm的物种则未受明显的影响。在茅口期晚期 ,由于灭绝压力的增大 ,除南京类外 ,所有类群及其物种无论个体大小均受到重创 ,导致类动物群物种分异度陡然下降研究结果证明 ,在灭绝强度较小时 ,类动物的生物学特征 ,如壳体大小、壳壁特征对物种的存活率有一定影响 ,而在集群灭绝的高峰期间 。Analyses of extinction process of Maokouan fusulinacean fauna show no general correlation between extinction intensity and shell size of the species. Changes of species diversity and net rate of species increase (R) are similar to each other in large specie group (shell length >6 mm ) and small species group (shell length ≤6 mm). However, significant differences have been found in the extinction process between 4 major fusulinacean clades possessing different morphological features, i.e., nankinellids, schwagerinids, verbeekinids and neoschwagerinids. Extinction of Maokouan fusulinacean fauna started in the middle Maokouan and intensified dramatically in the late Maokouan period. It has been demonstrated that in the early stage of extinction the number of species in nankinellids and neoschwagerinids, in small species group of verbeekinids and large species group of schwagerinids decreased apparently. Small species group of schwagerinids and large species group of verbeekinids were not affected until the late Maokouan period when extinction pressure greatly increased. Except the nankinellids, both small and large species groups in other clades were hit severely near the end of Makouan, leading to an abrupt decrease of species diversity in fusulinacean fauna. The results of this study suggest that such biological characters of fusulinaceans as shell size and test structures could have certain effects on the survivorship of species in early stage of mass extinction when extinction pressure is lesser intensive but are ineffectual during the extinction climax.

关 键 词：二叠纪 茅口期 TING类化石 集群灭绝 灭绝选择性 物种个体大小 

分 类 号：Q915[天文地球—古生物学与地层学]