TERMINALIA PALAEOPUBESCENS NOV. SP. (COMBRETACEAE), FROM THE FONSECA FORMATION (EOCENE/ OLIGOCENE), MINAS GERAIS STATE, BRAZIL: LEAF ARCHITECTURE, EPYPHYLLOUS FUNGI AND PALEOCLIMATE. In this study, well-preserved leaf-blade compressions and impressions from shale levels in the Fonseca Formation (Priabonian/Rupelian of the Fonseca Basin, state of Minas Gerais, southeastern Brazil) and associated epiphyllous fungi are described. Based on leaf architecture and indumentum, a new species is established, assigned to the extant tropical genus Terminalia L. (Combretaceae). The leaf of Terminalia palaeopubescens sp. nov. is mesophyll, narrow obovate and with an entire margin. Its secondary veins are camptodromous-brochidodromous, the tertiary pattern is percurrent mixed predominantly alternate, the quaternaries are alternate percurrent and the higher orders regular polygonal reticulate, with small and well developed areoles. Trichomes are present in the indumentum and are simple, slender, pointed, and with a swollen base, typical of the Combretaceae. Epyphyllous fungi, in the shape of microthyrioid disks of variable size and profusely colonizing the leaf surface, were assigned to Callimothallus Dilcher (Microthyriaceae). The presence of those biogenic structures (besides Phragmothyrites Edwards, already reported in the same levels of the Fonseca Formation) indicates that a prominent leaf mycoflora was associated to the vegetation, probably sustained by warm and humid conditions. The data here presented, analyzed together with other taxonomic, taphonomic and foliar physiognomic indicators, lead to the hypothesis that a dense rainforest, supported by heavy rainfall and high temperatures, was thriving near the banks and floodplain environments associated to fluvial systems of the Fonseca Formation, during the Eocene/Oligocene transition, in southeastern Brazil.

BONE HISTOLOGY OF THE TITANOSAUR BONITASAURA SALGADOI (DINOSAURIA: SAUROPODA) FROM THE UPPER CRETACEOUS OF PATAGONIA. The bone histology analysis of the titanosaur Bonitasaura salgadoi, from Río Negro Province, Argentina, was analysed in detail. It represents the first complete histological characterization of a South American sauropod based on a single specimen. Multiple samples were taken from different parts of the skeleton according to available fragmentary elements as well as to their paleohistological importance. The femur and humerus are characterized by a wide cortex mainly composed of primary, highly vascularized fibrolamellar tissue, interrupted by at least one growth mark. None of the samples show external avascular lamellar tissue (EFS). Samples from the ulna, one metacarpal and a caudal vertebral zygapophysis show histological similarities, allowing recognition of great internal remodeling with several generations of secondary tissue. Although very reduced, the primary fibrolamellar tissue was recognized with a LAG or annuli. In contrast, samples of dorsal ribs show a significant intraelemental variability. Only in proximal sections the fibrolamellar tissue has a notorious banding of longitudinal vascular canals, accompanied by at least two LAGs and a line of resorption. These features show that differential modeling process acted in the construction of these complex osseous elements. Finally, the recognized microstructural features allow the assignation of this specimen to a HOS (Histological Ontogenetic Stage) 9. The comparison with other known sauropod growth curves also allows inferring the adult femur length of this species reached up to 1.8–1.9 m.

VEGETATION HISTORY OF THE COASTAL PLAINS FROM SAMBOROMBÓN BAY (∼35.5° S), ARGENTINA, SINCE 7800 ¹⁴C YEARS. The palynological analysis from a sedimentary sequence, outcropping on the right bank of the Salado River (35° 55′ S - 57° 53′ W), 30 km from the present coastline of the Samborombón Bay, allowed to reconstruct the vegetation history for the central bay area since c. 7800 ¹⁴C years BP. Results indicate the development of different plant communities: middle-marsh halophytic vegetation between 7800 and 7000 ¹⁴C years BP, replaced by low-marsh brackish grasses between 7000 and 5400 ¹⁴C years BP in relation to sea-level highstand; a transitional high salt-marsh halophytic community, developed between 5400 and 4300 ¹⁴C years BP; and, brackish marsh vegetation and grasslands between 4300 and 1700 ¹⁴C years BP, with progressive decrease of estuarine conditions due to sea-level fall and littoral ridge progradation. These results along with those from the south of the Samborombón Bay and Mar Chiquita coastal plain (southeastern Buenos Aires province) showed a similar vegetation in the region, characterized by low-marsh and coastal lagoon halophytic grasses, developed between 5400 and 4300 ¹⁴C years BP; and a local differentiation after 4300 ¹⁴C years BP related to the geomorphology of each area: a brackish marsh vegetation in the Samborombón Bay, psammophytic communities at the south of the bay and middle salt-marsh halophytic communities in Mar Chiquita coastal plain. These changes reveal the sensitive response of vegetation from coastal marshes to the sea-level fluctuations and geomorphologic evolution.

PALYNOSTRATIGRAPHIC ANALYSIS OF PERMIAN DEPOSITS (HN-05-RS AND HN-25-RS BOREHOLES) FROM SOUTHERN PARANÁ BASIN. This paper presents the palynological results obtained from 133 levels of the HN-05-RS and HN-25-RS wells, drilled in Hulha Negra, southern portion of Rio Grande do Sul State. The sampled levels included the Permian units of the Gondwana I Supersequence (Itararé Group and Rio Bonito, Palermo, Irati, Serra Alta, Teresina and Rio do Rasto formations) from Paraná Basin, Brazil. A total of 133 palynomorph species were recorded, corresponding to spores (57), pollen grains (65), besides microplanktonic elements and fungi (11). The stratigraphic distribution of all taxa is presented, as well as the relative frequency of selected levels. The analysis allowed the recovery of palynological associations relatively diverse and abundant from the overlying levels of the Irati Formation, which were generally considered sterile. The associations are related to Vittatina costabilis (Asselian to middle Artinskian) and Lueckisporites virkkiae zones (middle Artinskian to Roadian). However, some particularities were observed, which suggest a better correlation with the informal proposals for the same basin in Uruguayan territory. Additionally, comparisons with other Gondwana Permian zonings are performed.

PALYNOLOGY OF THE PERMIAN OF THE CLAROMECÓ-COLORADO BASIN, ARGENTINA. We present a paleopalynological study of samples obtained from two boreholes (UTAL.CMM1. La Estrella x-1 and UTAL.CMM1. Cruz del Sur x-1) of the Claromecó-Colorado Basin, referred to Piedra Azul, Bonete and Tunas formations (Pillahuincó Group), which are Permian in age. One hundred and thirty-one species of spores (trilete and monolete), prasinophyte algae, acritarchs, fungi and pollen grains (monosaccate, bisaccate, striate and monosulcate) have been recorded. We also propose a new species Lunatisporites coloradensis sp. nov., and Falcisporites parvus (de Jersey) comb. nov., Falcisporites similis (Balme) comb. nov. and Tiwarisporis anaverrucosus (Archangelsky and Gamerro) comb.nov.. Two associations referred to a Cisuralian—Guadalupian age (Association I) and a Guadalupian—Lopingian age (Association II) are identified based on previous stratigraphic records of the identified species. The associations also show a variation in the proportions of the palynological components, showing a change in the environmental conditions, which range from a more favourable and humid period to another one characterized by water shortage and increase of the aridity.

SYSTEMATIC AND BIOSTRATIGRAPHIC CONSIDERATIONS ON THOATHERIOPSIS MENDOCENSIS SORIA, 2001 (LITOPTERNA, PROTEROTHERIIDAE). The revision of the Family Proterotheriidae has led to the study of the specimen MLP 81-XI-28-1 of Thoatheriopsis mendocensis Soria, found in the so-called Anfiteatro de Cacheuta (Mendoza Province, Argentina). We expanded the diagnosis, incorporating dental characters that were not considered previously. Its origin is uncertain, but it could correspond to the finding mentioned by Rolleri in an unpublished report, in the “Mariño beds”, without totally discarding the possibility of being Minoprio the collector of the fossil. We conclude that the specimen MLP 81-XI-28-1 comes from the Mariño Formation, though it cannot be established whether it comes from the Areniscas Entrecruzadas Member or the Estratos de Mariño Member, both outcropping at Anfiteatro de Cacheuta. It constitutes in any case a new faunal element of this formation and adds to the mammals found at the Areniscas Entrecruzadas in Divisadero Largo area (Mendoza; early Miocene). The phylogenetic analysis suggests that T. mendocensis, together with the clade that contains the Huayquerian Neobrachytherium intermedium (Moreno y Mercerat), the Santacrucian Thoaherium minusculum Ameghino, and the Montehermosan Epitherium laternarium Ameghino and Eoauchenia primitiva Ameghino, is closer to Diadiaphorus majusculus Ameghino (Santacrucian Age) than to Lophogonodon paranensis Ameghino (Huayquerian Age). These results suggest that some lineages of Proterotheriidae recorded between the middle and late Miocene had an origin in an early diversification (Santacrucian), and they are unequally recorded both geographically and stratigraphically. A future analysis with a broader sampling of taxa and characters may confirm this hypothesis.

This study analyzes a collection of fossil mammals from the Salicas Formation in the El Degolladito area, La Rioja Province, Argentina. The materials reported herein were recovered from two sites (site 1 and site 2). Reported mammals are Macrochorobates Scillato-Yané, Chasicotatus Scillato-Yané, and Hoplophorini indet. (Xenarthra, Cingulata); Paedotherium minor Cabrera, cf. Pseudotypotherium Ameghino (Notoungulata, Typotheria); Neobrachytherium Soria (Litopterna, Lopholipterna); Orthomyctera Ameghino, cf. Cardiomys Ameghino, Lagostomus (Lagostomopsis) Kraglievich, and Octodontidae indet. (Rodentia, Caviomorpha). This new mammalian assemblage, together with one previously recorded, has several taxa in common with mammalian associations from Central Argentina (i.e., La Pampa Province). Among those coming from Northwestern Argentina, the major affinity is with the El Jarillal Member (Chiquimil Formation) and then the Andalhuala Formation (both in Catamarca Province). The Salicas Formation fauna is considered as latest Miocene in age until new fossil discoveries and radioisotopic dates allow a better calibration. The fossil biota and geological data suggest that the Salicas Formation was deposited in flatlands, under warm and dry conditions. This environment was probably dominated by open grasslands, with forested areas near rivers and lagoons.

SIZE AND BODY MASS IN PROCARIAMA SIMPLEX ROVERETO, 1914 (AVES: PHORUSRHACIDAE: PSILOPTERINAE). Body-mass of fossil birds can be estimated using comparisons with extant birds, taking into account that the measures of hindlimbs are indicators of body weight. Hindlimb bones (femur, tibiotarsus, and tarsometatarsus) would represent a direct relationship with body mass, because they provide, in different degrees, the support of the body. In this contribution, the body-mass of fossil specimens of Procariama simplex Rovereto from the Miocene of Argentina is calculated using two different estimates. The first model assumes that there is geometric similarity between fossil and analogous extant birds, in this case between Procariama simplex and its analogous Cariama cristata Linnaeus. The second model, more used in birds, considers the influence of the size or body-mass on the form and function of the skeleton. It considers the logarithmic relationship between body-mass and the minimum circumference of the shaft of the hindlimb elements involved in the support of a bird. Both models estimate values between 10 and 13 kg for Procariama simplex, higher than previous estimates. These values resemble in size (mass) those of a Patagonian rhea Pterocnemia pennata d'Orbigny. Although this Rheidae is not related phylogenetically to Phorusrhacidae, they share the same morphotype with long hindlimbs, suitable for running.