A large collection of conodonts (over 4200 elements) from the Santa Gertrudis Formation of the Cordillera Oriental, NW Argentina, is analyzed. The mostly endemic fauna of this unit and the lack of index species require complex taxonomic and biostratigraphic interpretations. We determined new species apparatuses by reviewing previous literature with a different taxonomic approach: Erismodus saltaensis n. sp., Erraticodon aldridgei n. sp., Gallinatodus elegantissimus n. gen. et sp., Pyramidens cactus n. gen. et sp., P. spinatus n. gen. et sp., Zentagnathus gertrudisae n. sp. Although the lack of key conodont species for intercontinental correlation precludes biostratigraphic assignment to a particular biozone, the overlapping ranges of recorded species restrict the age range to the upper Lenodus variabilis, Yangtzeplacognathus crassus and the lower Eoplacognathus pseudoplanus zones, of middle Darriwilian age (Dw2, Middle Ordovician). The depositional environment of the Santa Gertrudis Formation is primarily a shallow inner platform influenced by waves but not by storms; its paleogeographic location in mid-high latitudes exerts important control over the conodont biofacies, similar to the Arabian Darriwilian faunas of the Gondwanan margin. A narrow marine seaway along the suture zone connecting East and West Gondwana is proposed to explain the evolution of lineages of shallow cold-water conodont faunas from the Middle Ordovician onwards.

分析了阿根廷西北部东山脉 Santa Gertrudis 组的大量牙形石（超过 4200 个元素）。该单元的大多数地方性动物群和缺乏指标物种需要复杂的分类学和生物地层学解释。我们通过使用不同的分类学方法回顾以前的文献来确定新物种装置：Erismodus saltaensis n。sp., Erraticodon aldridgei n. sp., Gallinatodus elegantissimus n. 将军 et sp., Pyramidens cactus n. 将军 et sp., P. spinatus n. 将军 et sp., Zentagnathus gertrudisae名词 sp。虽然缺乏用于洲际对比的关键牙形石物种排除了生物地层学对特定生物带的分配，但记录物种的重叠范围将年龄范围限制在上层 Lenodus variabilis 、Yangtownplacognathus crassus 和下层Eoplacognathus pseudoplanus带，中Darriwilian 时代（Dw2，中奥陶世）。Santa Gertrudis 组的沉积环境主要是受波浪影响但不受风暴影响的浅内台地；其在中高纬度的古地理位置对牙形石生物相具有重要控制作用, 类似于冈瓦纳边缘的阿拉伯 Darriwilian 动物群。提议沿着连接东西冈瓦纳大陆的缝合带建造一条狭窄的海洋航道，以解释自中奥陶世以来浅层冷水牙形石动物群谱系的演化。