A new assemblage of large insect trace fossils is recognized in paleosols of the middle Miocene pyroclastic deposits from extra-Andean north Patagonia. This assemblage includes Racemusichnus jacobacciensis igen. isp. nov., the largest trace fossil in paleosols attributed to solitary insects. R. jacobacciensis is represented by clusters of two to seven thickly walled cylinders horizontally orientated in the paleosol. The cluster arrangement, its orientation, the large size and wall of the cylinders suggest a dung beetle, probably a representative of the Geotrupidae as the possible trace maker. The new ichnoassemblage, also comprising large-sized specimens of Coprinisphaera ispp., Teisseirei barattinia and Feoichnus challa, belongs to the Rosellichnus assemblage-SAPIA of the Coprinisphaera Ichnofacies. Mollic paleosols along with the trace fossils, mammal remains and previous data for this unit suggest an open grassy habitat compatible with high productive grass savannas, under a temperate-warm and seasonal subhumid climate. This assemblage of large-sized trace fossils is attributed to highly productive ecosystems related to the rise of temperature occurred during the Middle Miocene Climatic Optimum.

在安第斯山脉北部巴塔哥尼亚地区的中新世中新世碎屑沉积物的古土壤中发现了一种新的大型昆虫痕迹化石组合。此集合包括Racemusichnus jacobacciensis igen。isp。十一月，是古土壤中最大的微量化石，归因于孤独的昆虫。雅各杆菌以在古土壤中水平定向的两到七个厚壁圆柱体簇为代表。簇的排列，其方向，较大的圆柱体尺寸和壁突表明有甲虫，可能是象鼻虫科的代表，可能是痕迹制造者。新的鱼鳞组合，也包括大粉金鱼科的ispp的标本。，Teisseirei barattinia和Feoichnus challa，属于Rosellichnus所述的组合-SAPIA Coprinisphaera遗迹相。软体动物的古土壤以及痕迹的化石，哺乳动物的遗骸和该单位的先前数据表明，在温带-温暖和季节性的半湿润气候下，与高生产力草大草原兼容的开放式草丛生境。大型痕迹化石的这种集合归因于与中新世气候最佳时期发生的温度升高有关的高产生态系统。