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In this work, we present several new materials collected at the pink sandstone levels from the Las Flores Formation at the Cerro Pan de Azúcar (Gaiman, Chubut Province, Argentina) and compare them with taxa present in other localities of similar age. The Metatheria taxa described here are 1) the 'Ameridelphia' Sternbergiidae indet; 2) the Didelphimorphia Protodidelphis cf. mastodontoides and Guggenheimia glykeia sp. nov. (Protodidelphidae); 3) the Polydolopimorphia Pliodolops rothi and Pliodolops cf. kamektsen (Polydolopidae); and 4) the Microbiotheria Eomicrobiotherium diluculum sp. nov. (Microbiotheriidae). On the other hand, the Cingulata Dasypodidae is represented by the Astegotheriini Prostegotherium astrifer. This fauna shares more species with those occurring in the localities from Paso del Sapo than with any other early – middle Eocene localities. However, at the generic level, it shares several taxa with the Itaboraian fauna from Sao José de Itaboraí. Finally, the faunal associations from Pan de Azúcar, Paso del Sapo, Cañadón Hondo, and Bajo de la Palangana could be, at least in part, synchronous, representing locally the Riochican SALMA, with an age spanning from 51 to 45 Ma (early Ypresian- early Lutetian). [ABSTRACT FROM AUTHOR]

In the Eocene deposits of Northwestern Argentina, the order Cingulata was recognized in the sedimentary levels of the upper and lower sections of the Lumbrera (Salta Province), Geste (Catamarca and Salta provinces), Quebrada de Los Colorados (Salta Province), and Casa Grande (Jujuy Province) formations. The traditional biochronological scheme associated the Geste Formation to the Mustersan SALMA (37.3–35.4 Ma; Priabonian), the lower section of the Lumbrera Formation to the Vacan Subage (44–46 Ma; Lutetian) of the Casamayoran SALMA, and the fossiliferous levels of the remaining units to the Barrancan Subage (39–42 Ma; Bartonian) of the Casamayoran SALMA. Nevertheless, recent dating obtained for the top of the lower section of the Lumbrera Formation supports a new geochronological framework for Northwestern Argentina, which changes the temporal assignation of the taxa that have been collected in this section, going from the Vacan Subage to the Itaboraian SALMA, affecting also the biochronology of the Quebrada de Los Colorados and the upper section of the Lumbrera formations, which are now constrained between 46 and 40 Ma (Lutetian). In this contribution, we present a new cingulate assemblage based on osteoderms collected in the basal levels of the Quebrada de Los Colorados Formation at Los Cardones National Park, Calchaquí Valley (Salta, Northwestern Argentina), which is constituted by a new taxon plus Pucatherium parvum and Parutaetus punaensis. In addition, we discuss all the Eocene cingulate associations reported for Northwestern Argentina taking into consideration the new geochronological framework. [Display omitted] • New cingulate assemblage from the middle Eocene Quebrada de Los Colorados Fm (Los Cardones National Park, Salta, Argentina). • The assemblage is composed by the new taxa Saltatherium rosaurae plus Pucatherium parvum and Parutaetus punaensis. • An updated biochronology for the middle Eocene of Northwestern Argentina is presented. • The mammalian fauna of the QLCF is constrained between the late Vacan and the Barrancan subages of the Casamayoran SALMA. [ABSTRACT FROM AUTHOR]