In this paper we compare the diversity of Floian (Lower Ordovician) conodonts from the Precordillera with that of the Cordillera Oriental, Argentina. The comparative analysis is restricted to the middle Floian Stage Slice (Fl2) from correlative intervals: Oepikodus evae Zone (Juanognathus variabilis Subzone) in the Precordillera and the Gothodus andinus Zone in the Cordillera Oriental. For the comparative analysis, absolute frequency tables of the conodont data from published articles and collections under study, were prepared. These include four sections of the Precordillera with 13 samples recovered from the middle section of the carbonate San Juan Formation, and six sections of the Cordillera Oriental with 28 samples from the middle-upper section of the shaly Acoite Formation. Diversity patterns and indices were generated from absolute frequencies using the software PAST 4.03. Remarkable differences in the species richness and diversity between coeval communities of referred basins are displayed. Comparisons with other basins elsewhere suggest that the paleolatitudinal gradient is not a major factor controlling changes in diversity, which may be due to a response to the complex interaction of biological and physico-chemical factors.

在本文中，我们比较了来自普雷迪勒拉山脉和阿根廷东科迪勒拉山脉的弗洛安（下奥陶统）牙形刺的多样性。比较分析仅限于相关区间的中弗洛阶段切片（Fl2）：Precordillera 中的Oepikodus evae区（Juanognathus variabilis亚区）和Gothodus andinus东科迪勒拉山脉地带。为了进行比较分析，准备了来自所研究的已发表文章和收藏的牙形刺数据的绝对频率表。其中包括 Precordillera 的 4 个剖面，从碳酸盐 San Juan 组中段回收了 13 个样品，以及东方山脉的 6 个剖面，从页岩 Acoite 组的中上部回收了 28 个样品。使用软件 PAST 4.03 根据绝对频率生成多样性模式和指数。显示了所涉及流域的同时代群落之间物种丰富度和多样性的显着差异。与其他盆地的比较表明，古纬度梯度并不是控制多样性变化的主要因素，