The Cerro Bandera Formation is a mostly pyroclastic continental unit exposed in isolated areas of east-central Neuquén Province, northwestern Patagonia. Several mammals from these deposits were previously reported and support a Colhuehuapian age (early Miocene) for these levels. New findings reveal that this unit bears a much more diverse assemblage and calls into question this age assessment. Here we describe three new species. Protypotherium sinclairi sp. nov. (Notoungulata, Interatheriidae) is similar in size to the Santacrucian Protypotherium australe Ameghino, but differs from all the species of the genus by having less reduced p3–p4 talonids. Doryperimys olsacheri gen. et sp. nov. (Rodentia, Neoepiblemidae) has hypselodont, prismatic cheek teeth that combine features of species of Perimys Ameghino and Scotamys antiquus Loomis. The systematic position of Leucokephalos maior sp. nov. within Caviomorpha is still uncertain, but it is definitively allied to the Deseadan Leucokephalos zeffiae Vucetich, Dozo, Arnal, and Pérez in sharing rooted cheek teeth with an almost identical early occlusal simplification that resembles the 8-shaped configuration of some early octodontoids and putative chinchilloids. The three species co-occur at a single fossil locality and stratigraphic level on the northeastern slope of Barda Negra; P. Sinclairi and D. olsacheri are also recorded in other levels exposed in different isolated outcrops of the Cerro Bandera Formation. Doryperimys olsacheri—like other previously described rodents from this unit— is unknown in other presumably coeval mammal associations, but the biochronological and paleobiogeographic meaning of this assemblage is still under study.

Ostracod species living in 13 ponds (25 sample points) in Bardenas Reales de Navarra Natural Park and World Biosphere Reserve are studied for the first time. Nineteen species were identified, nine of them being the most abundant. According to statistical analyses (cluster and Correspondence Analysis), the distribution of ostracod species in this semi-arid area is mainly controlled by water conductivity and pH. The hydroperiod, sediment type, dissolved oxygen, altitude and vegetation cover play a secondary role. Thus, in semi-permanent waters with conductivity between 4.5 and 5.4 mS/cm and pH from 7.95 to 8.73 the most abundant species is Sarscypridopsis aculeata (Costa). In ponds with water conductivity from 0.3 to 2 mS/cm, pH between 7.1 and 7.78 and dissolved oxygen from 0.1 to 7.95 mg/l, Cypridopsis vidua (Müller) s the most abundant species. When the vegetation cover increases in this type of ponds, Limnocythere inopinata (Baird) and Potamocypris villosa (Jurine) appear as more abundant. Finally, in ponds with conductivity between 0.34 and 2.8 mS/cm and sporadic input of running waters llyocypris bradyi Sars, is the most important species. When the internal water current increases in these ponds, Pseudocandona albicans (Brady) appears as most abundant. However, the accumulation of dead organic matter within the bottom sediment of these ponds favours the decrease of dissolved oxygen and the development of Eucypris virens (Jurine). With this work, we contribute to the knowledge of the ostracod biodiversity of this semi-arid environment and the ecological preferences of this group.

New palynological information from the El Paso Formation cropping out at the southern Sierra de Barreal (Calingasta-Uspallata Basin), San Juan Province, Argentina is presented. The palynologic assemblages were recovered from the middle to upper part of the section. Abundant trilete (75–90%) and hilate (1–57%) spore species are recognized: Cyclogranisporites rinconadensis, Apiculatisporis variornatus, Raistrickia rotunda, Tricidarisporites gutii, Ahrensisporites sp. cf. A. cristatus, Cristatisporites stellatus, Indotriradites volkheimeri, Vallatisporites ciliaris and Psomospora detecta, among others. Also, subordinate pollen grains (1.5–207%): Circumplicatipollis plicatus, Costatascyclus crenatus, Plicatipollenites sp. cf. P. malabarensis, Potonieisporites spp. and Divarisaccus sp. cf. D. stringoplicatus. Recycled and autochthonous acritarchs (e.g., Cymatiogalea sp., Gorgonisphaeridium sp., Verhyachium sp.) and Zygnematalean algae (Tetraporina sp., Brazilea scisa) with less of 2.57% are also present. We propose a late Serpukhovian-Bashkirian age, and a correlation with the Subzone A of the Raistrickia densa-Convolutispora muriornata (DM) Biozone to the El Paso assemblages.

Nine gastropod species are reported from early Bajocian marine deposits at two localities in the Neuquén Basin, supplying the first detailed documentation of six gastropod families from the Middle Jurassic of Argentina at that time. The new gastropod species include Pleurotomaria bajociana sp. nov. (Pleurotomariidae); Cryptaulax weaveri sp. nov. and Rhabdocolpus(Infacerithium) excavatus sp. nov. (Procerithiidae); Anulifera sigmoidea sp. nov. (Protorculidae); Globularia andina sp. nov. (Ampullinidae); Eunerinea? neuqueniana sp. nov. (Eunerineidae) and Promathildia? spinosa sp. nov. (Gordenellidae). Leptomaria? leufuensis (Weaver) and Globularia klingamanni(Weaver) are also recorded from the same localities. Rhabdocolpus (Infacerithium) and Promathildia are mentioned here for the first time in the Argentinean Mesozoic, and Cryptaulax, Anulifera and Eunerinea extend their chronostratigraphical and paleogeographical distribution into the Bajocian of South America.