Adrain JM, Fortey RA, Westrop SR
J. M. Adrain and R. A. Fortey, Department of Palaeontology, Natural History Museum, Cromwell Road, London SW7 5BD, UK. S. R. Westrop, Oklahoma Museum of Natural History and School of Geology and Geophysics, University of Oklahoma, Norman, OK.
Science. 1998 Jun 19;280(5371):1922-5. doi: 10.1126/science.280.5371.1922.
A cluster analysis of the stratigraphic distribution of all Ordovician trilobite families, based on a comprehensive taxonomic database, identified two major faunas with disjunct temporal diversity trends. The Ibex Fauna behaved as a cohort, declining through the Ordovician and disappearing at the end-Ordovician mass extinction. In contrast, the Whiterock Fauna radiated rapidly during the Middle Ordovician and gave rise to all post-Ordovician trilobite diversity. Its pattern of diversification matches that of the Paleozoic Evolutionary Fauna; hence, trilobites were active participants in the great Ordovician radiations. Extinction patterns at the end of the Ordovician are related to clade size: Surviving trilobite families show higher genus diversity than extinguished families.
基于一个全面的分类数据库，对所有奥陶纪三叶虫科的地层分布进行聚类分析，确定了两个主要动物群，它们具有不连续的时间多样性趋势。伊比克斯动物群表现为一个群组，在奥陶纪期间逐渐减少，并在奥陶纪末期的大灭绝中消失。相比之下，怀特洛克动物群在中奥陶世迅速辐射，并产生了所有奥陶纪后的三叶虫多样性。其多样化模式与古生代进化动物群的模式相匹配；因此，三叶虫是奥陶纪大辐射的积极参与者。奥陶纪末期的灭绝模式与类群大小有关：幸存的三叶虫科的属多样性高于灭绝的科。
