LOWER MIOCENE BIRD AND MAMMAL FOOTPRINTS FROM LA RIOJA (EBRO BASIN, SPAIN). A new site carrying vertebrate footprints is described at Cenicero (Ebro Basin, Spain). The footprints are preserved in sandstone beds located within the “Transition Unit”, between the Agenian (early Miocene) Nájera and Haro formations. This level is placed between local biozones Y and Z. Fourteen blocks are studied; they contain 72 bird, 46 artiodactyl, and six perissodactyl footprints. Bird footprints include two ichnotaxa. The first one includes large to enormous tetradactyl footprints, with an incumbent hallux. It is identified as Gruipeda cf. maxima Panin and Avram. The second bird ichnotaxon is tridactyl with a prominent central pad, very large to enormous and with toes not joining at the proximal end. The latter feature suggests that it is probably a new bird ichnotaxon. Several ichnogeneric taxobases are proposed for bird footprints with the purpose of unifying the existing criteria between studies on extant and fossils bird ichnites. The artiodactyl footprints are small and identified as the ichnogenus Pecoripeda Vialov. The perissodactyl tracks are small and monodactyl, produced by equids, and classified as cf. Hippipeda Vialov.

Eighty-one species of spores and pollen grains together with algae and fungi remains were recovered from the shallow lacustrine successions of the La Veteada Formation at the Chaschuil river section (27°43′50.5″S-68°01′17.0″W), Sierra de Narváez, Catamarca Province, Famatina Range, which are herein described and/or illustrated. This palynoflora is composed dominantly by a diverse association of taeniate pollen groups (68%), bisaccate (non-taeniate) pollen grains (24%), with less significant proportions of spores. The studied palynoflora is referred to the upper part of the LW (Lueckisporites-Weylandites) Biozone, thus a Middle Permian (Guadalupian) age is established, mainly based on the presence of Corisaccites alutas Venkatachala and Kar, Lueckisporites angoulensis Jardiné, L. nyakapandensis Hart, L. stenotaensis Menéndez, L. virkkiae (Potonié and Klaus) Clarke, Lunatisporites variesectus Archangelsky and Gamerro, Staurosaccites cordubensis Archangelsky and Gamerro, Striatoabieites anaverrucosus Archangelsky and Gamerro, Vittatina corrugata Marques-Toigo, V. costabilis Wilson, V. subsaccata Samoilovich, Convolutispora archangelskyi Playford and Dino, Striomonosaccites cicatricosus Archangelsky and Gamerro. Several species are recorded for the first time in Permian strata from Argentina, extending their chronostratigraphic records. Lueckisporites balmei (Tiwari and Vijaya) comb. nov. is proposed. Gondwanic biostratigraphic distribution of selected species recorded in this assemblage is presented in a range-chart. This palynofloral association is composed mainly by allochthonous elements derived from gymnosperms, conifers and pteridosperms, together with rare authochthonous elements related to the local vegetation represented by pteridophyte and sphenophyll components. Warm arid and/or semiarid climatic conditions prevailed in the Paganzo Basin during deposition of the La Veteada Formation.

TRIASSIC PLANTS AND THEIR RELATIONSHIPS WITH THE VOLCANISM IN THE AGUA DE LA ZORRA FORMATION, MENDOZA PROVINCE, ARGENTINA. Fosssil plants were recovered from the upper levels of the Triassic Agua de la Zorra Formation, Cuyo Basin, Mendoza Province, Argentina. The formation represents a fluvio-lacustrine environment affected by volcanism. The plant assemblage is dominated by Corystospermales (Dicroidium, Johnstonia and Xylopteris), with subordinate Equisetales and Osmundales. Abundant amorphous organic matter, together with scarce botryoidal colonies of the green algae Botryococcus are also present in the plant bearing levels. Notwithstanding the fact that strata yielding fossil plants are commonly associated with basaltic peperites, the kerogen of these levels displays low to moderate thermal alteration, suggesting that the sediments of the bottom were not extensively unsettled by the episodic entrance of basaltic lava in the freshwater body.

SEARCHING ECOMORPHOLOGICAL PATTERNS SHARED BY EXTANT UNGULATES AND EXTINCT XENARTHRANS. The scarce number of extant representatives of the Order Xenarthra offers a poor idea of the large morphological diversity that existed in the past. Because of this, the interpretation of the ecology of those extinct species is problematic. In order to understand the relationship between diet and habitat, the variability of the lower jaw of different mammals (mainly ungulates and xenarthrans) is analysed in this work by means of geometric morphometric methods. Using principal component and discriminant analyses, the main objective of this contribution is to find taxon-free ecomorphological patterns, which could be applied to extinct xenarthrans with the aim of inferring their ecology. Most part of the variance is due to the phylogenetic factor. However, part of the variability can be interpreted in ecological terms. Because of their characteristic craniodental morphology, glyptodonts occupy their own particular area of the morphospace. Vassallia maxima is proposed as a mix-feeder of mixed habitats, which agrees with previous results. For those sloth species which lower jaw is more similar to that of ungulates, discriminant analysis renders similar results to those obtained in the literature. On the contrary, sloth species with a more different morphology show results more coherent with previous studies by means of principal component analysis. The discriminant functions are not suitable to infer habitat in the Pleistocene mylodontids. Because ruminant species have a mandibular angle proportionally more developed for all diets, discriminant functions are not totally independent of phylogeny.

ASSEMBLAGES OF BENTHIC FORAMINIFERA FROM HOLOCENE SECTIONS IN THE BAHÍA BLANCA ESTUARY (BUENOS AIRES, ARGENTINA). Benthic foraminifera associations are described from two Holocene sections, Canal Tres Brazas (38°54′S–62°14′W) and Canal del Medio (38°49′S–62°17′W), in the Bahía Blanca estuary, Buenos Aires Province. Micropaleontological analysis shows that both sections represent low intertidal to subtidal estuarine environments, affected by sea-level variations during the late Holocene. Among hyaline foraminifera, Buccella frigida (Cushman, 1922) dominates in both sections, mainly associated to Elphidium gunteri Cole (1931) and other species of Elphidium Montfort, 1808. Also present, but in low proportions are Ammonia tepida (Cushman, 1926) and Ammonia parkinsoniana (d'Orbigny, 1839) with bolivinids such as Bolivina striatula Cushman (1922) and Bolivina pseudoplicata Heron-Allen and Earland (1930). Among the most conspicuous miliolids are Miliolinella subrotunda (Montagu, 1803) and Quinqueloculina seminulum (Linné, 1767). The Canal del Medio section, dated at about cal. 3700 years BP represents a low intertidal to shallow subtidal estuarine environment, revealing energy oscillations in the depositional environment attributed to the cyclical action of tides. Features of these deposits indicate that the mean sea level at 3831–3610 years BP was located in a similar position to that of the present one. The Canal Tres Brazas section, the base of which was dated in cal. 1589–1371 years BP, shows a typical shallow intertidal fauna that gradually gives way to environments with greater continental influence, and without microfosiliferous content.

Early Devonian trilobites are described based on material from Sierra de Las Minitas, in the northern extent of the Precordillera, western Argentina. This diverse fauna, the first one known from La Rioja Province, includes a species of the phacopid Paciphacops (Paciphacops) Maksimova, the calmoniids Talacastops zarelae Edgecombe, Vaccari and Waisfeld and Tormesiscus Waisfeld, Edgecombe and Vaccari, together with a proetid (Unguliproetus? sp.) and a dalmanitid. Fossils are preserved in nodules within a strongly folded dark and bioturbated shaley succession, included in a structural and stratigraphically complex geological setting. The taxonomic composition and taphonomic signature of the studied fossil locality are closely similar to those recognized within the lower part of the Talacasto Formation at Las Aguaditas section in San Juan Province. Lithologic and faunistic similarities allow a reliable stratigraphic correlation between both localities; therefore, the trilobite bearing rocks from the Sierra de Las Minitas are interpreted as the northernmost outcrops of the Talacasto Formation in the Argentine Precordillera and are considered to be Lochkovian in age. The remarkable lateral continuity of this fossiliferous stratigraphic interval indicates, as previously suggested, the development of a wide muddy-shelf setting in the Early Devonian Precordillera Basin.

LATE TREMADOCIAN (ORDOVICIAN) CONODONTS AND GRAPTOLITES FROM THE SIERRA DE ZENTA, CORDILLERA ORIENTAL OF JUJUY, ARGENTINA. A thick heterolithic Ordovician succession lies exposed in the Zenta Range of the Cordillera Oriental, Jujuy Province, Argentina. It is mostly siliciclastic with subordinated calcareous concretions, coquinas and calcarenites, and bears a significant conodont and graptolite fauna. The sampled localities are situated on the road running from Abra de Zenta to Santa Ana, within a wide anticline structure. Exposures of gray shales and coquinas near Abra de Santa Ana, yielded a low diversity conodont fauna that includes Acodus apex n. sp., Drepanoistodus chucaleznensis Albanesi and Aceñolaza, and Drepanoistodus costatus (Abaimova), which are referred to the lower part of the Acodus deltatus — Paroistodus proteus Zone. The diagnosis of the conodont genus Acodus is emended. The A. murrayi Zone is suggested by a graptolite assemblage including Araneograptus murrayi (J. Hall), Kiaerograptus cf. K supremus Lindholm and Kiaerograptus? sp., which was collected from strata overlying the conodont-bearing levels. These conodont and graptolite faunas indicate a late Tremadocian age. Another locality on the road to Abra de Zenta, west of Santa Ana, contains Hunnegraptus cf. H. novus (Berry), Hunnegraptus spp. and Paradelograptus sp., indicating the Hunnegraptus copiosus Zone of the latest Tremadocian. The biostratigraphic succession is equivalent to that from the upper part of the Santa Rosita Formation and to the Parcha Formation exposed in other areas of the Eastern Cordillera in northwestern Argentina. The faunas contain elements of wide intercontinental distribution as well as endemic forms. The occurrence of concentrations of graptolites and lingulids showing evidence of transport in some strata indicates bottom reworking by erosive episodes in the basin.