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We conducted a geochemical analysis on three sediment cores collected from soda and freshwater lakes in the Pantanal region, in Brazil. Our objective was to identify the primary sources of organic matter associated with the Pleistocene-Holocene transition, as previously documented in that area. The Nhecolandia region, located in the Pantanal, encompasses over 10,000 lakes, with approximately 10% of them exhibiting alkaline characteristics. Soda lakes became highly saline and alkaline after ~ 910 cal yr BP, which influences biogeochemistry and aquatic ecology. They have high electrical conductivity and pH can reach 10.5. In contrast to freshwater, soda lakes are absent of surrounding vegetation. Literature suggests a strong influence by the Last Glacial Maximum on the region. We hypothesized that periods of aridity and increased precipitation influenced the composition of organic matter present in sediments and preserved within these cores. Our analysis focused on examining the presence and distribution of fatty acids, organic carbon content, and total nitrogen. In general, the cores exhibited two distinct parts in terms of organic matter sources: the upper sections of the cores were primarily composed by terrestrial sources, identified by the presence of long-chain fatty acids, while the deeper sections were dominated by aquatic sources, therefore short-chain fatty acids. We did not find significant difference among fatty acid profile that could distinguish freshwater from soda lakes, the only remarkable difference was the occurrence of saturated fatty acids, which is lower in freshwater lake. These findings suggest the occurrence of humid and arid periods in the region. The C/N ratio displayed a similar trend to the fatty acid's profiles, exhibiting an abrupt change that was likely induced by climate variations. Although diagenesis can alter the composition of organic matter and, subsequently, the C/N values, it is noteworthy that the abrupt change observed in the Salina da Ponta (soda lake) core corresponds to 3,200 years BP. This coincides with documented climate changes that occurred during the Holocene. Our study revealed the influence of past climatic conditions on the sources and variations of organic matter in sediment cores from the Pantanal's soda and freshwater lakes. Consideration of diagenesis and climate variations is crucial for interpreting sedimentary records.

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The dynamics of the taxonomic diversity of the birds of Cuba during the Late Pleistocene-Holocene is assessed for the first time using material from El Abrón Cave in the western part of the island. The Upper Pleistocene beds of the locality are characterized by a rich taxonomic diversity of birds, including an abundance of waterbirds and open-landscape inhabitants. For the Holocene, a general decrease in taxonomic diversity and a significant increase in the number of remains belonging to representatives of forest faunas (Picidae) are recorded. Our data indicate a significant transformation of landscapes of western Cuba and the faunistic associations of birds at the end of the Quaternary, which is consistent with paleoclimatic data.

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The presence of deciduous premolars and erupting C1, P2, P4, I1, I2, I3, P2, and P4 in Nesophontidae is established for the first time on the fossil remains of Nesophontes major Arredondo, 1970, and N. micrus Allen, 1917 from El Abrón Cave (Republic of Cuba, Pinar del Río Province, Late Pleistocene). During ontogenesis, the replacement of teeth (except P1 and P1) occurred after the molar eruption, but before the animal reached adult size. By the dental replacement pattern nesophontids differ from most members of Lipotyphla and are close to Solenodontidae.

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The study of the remains of Nesophontes micrus Allen, 1917 and N. major Arredondo, 1970 from El Abrón Cave (Republic of Cuba, Pinar del Río Province, Late Pleistocene) allowed to establish for the first time anomalies of the dentition in Nesophontidae. Failures of eruption of teeth (impaction of I3 in N. micrus, retention or impaction of P2 in N. major), as well as malformations (aberrant I3 in N. micrus, P2 and P4 in N. major), are the developmental abnormalities. The absence of P2 and M2 in combination with reossification of their alveoli in N. major is caused by dental injuries and diseases.

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The application of statistical modeling is still infrequent in mercury research in peat, despite the ongoing debate on the weight of the diverse factors (climate, peat decomposition, vegetation changes, etc.) that may affect mercury accumulation. One of the few exceptions is the Hg record of Pinheiro mire (souheast Brazil). Previous studies on this mire modeled mercury using principal components regression and partial least squares. These methods assume independence between factors, which is seldom the case in natural systems, thus hampering the identification of mediating effects and interactions. To overcome these limitations, in this reserach we use structural equation modeling (PLS-SEM) to model mercury and bromine peat records - bromine has been used in some investigations to normalize mercury accumuation. The mercury model explained 83% of the variance and suggested a complex control: increased peat decomposition, dust deposition and humid climates enhanced mercury accumulation, while increased mineral fluxes resulted in a decrease in mercury accumulation. The bromine model explained 90% of the variation in concentrations: increased dust deposition and peat decomposition promoted bromine accumulation, while time (i.e. peat age) promoted bromine depletion. Thus, although mercury and bromine are both organically bound elements with relevant atmospheric cycles the weights of the factors involved in their accumulation differed significantly. Our results suggest caution when using bromine to normalize mercury accumulation. PLS-SEM results indicate a large time dependence of peat decomposition, catchment mineral fluxes, long-term climate change, and atmospheric deposition; while atmospheric dust, mineral fluxes and peat decomposition showed high to moderate climate dependency. In particular, they also point to a relevant role of autogenic processes (i.e. the build up and expansion of the mire within the catchment), which controlled local mineral fluxes; an aspect that has seldom been considered.

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A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology.

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OBJECTIVES: To increase understanding of the subsistence practices of the first Americans through analysis of the near-complete dentition of a young woman dating to the terminal Pleistocene of the Yucatan Peninsula, Mexico. MATERIALS AND METHODS: The skeleton is that of "Naia" a 15 to 17-year-old female from the submerged natural trap of Hoyo Negro found in association with remains of numerous extinct species of megafauna. Superbly preserved remains included the skull with 28 teeth, which are analyzed for evidence of caries, periodontal disease, wear patterns, and malocclusion. RESULTS: Naia exhibits a high frequency of dental caries, along with aggressive periodontal disease that threatened all her teeth, particularly her incisors. Dental attrition was extremely light for a hunter-gatherer, reaching to four on the Molnar scale on only one tooth. Lack of wear is associated with severe mandibular retrognathia, and low masticatory forces. DISCUSSION: Naia's dental condition is compared with that of other northern Paleoamericans, mostly females, dating before 11,000 cal BP. These exhibit a high degree of variability in both caries and tooth wear. All, however, exhibit rapid anterior wear owing to technological use of the front teeth. Naia exhibits the highest rate of caries, similar to that of the earliest South Americans, and one of the lowest rates of attrition. This demonstrates that she had a nonabrasive diet that was at least seasonally rich in carbohydrates. This does not mean her diet was low in meat, however, because similarly light dental attrition is seen in the Arch Lake female, a Paleoamerican from a big-game hunting society.

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The Great American Biotic Interchange is considered to be a punctuated process, primarily occurring during four major pulses that began approximately 2.5 Ma. Central America and southeastern Mexico have a poor fossil record of this dynamic faunal history due to tropical climates. Exploration of submerged caves in the Yucatán, particularly the natural trap Hoyo Negro, is exposing a rich and remarkably well-preserved late Pleistocene fauna. Radiometric dates on megafauna range from approximately 38 400-12 850 cal BP, and extinct species include the ursid Arctotherium wingei and canid Protocyon troglodytes. Both genera were previously thought to be indigenous to and confined to South America and appear to represent an instance of large placental mammals, descended from North American progenitors, migrating back north across the Panama Isthmus. This discovery expands the distribution of these carnivorans greater than 2000 km outside South America. Their presence along with a diverse sloth assemblage suggests a more complex history of these organisms in Middle America. We suggest that landscape and ecological changes caused by latest Pleistocene glaciation supported an interchange pulse that included A. wingei, P. troglodytes and Homo sapiens.

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Simple pebble tools, ephemeral cultural features, and the remains of maritime and terrestrial foods are present in undisturbed Late Pleistocene and Early Holocene deposits underneath a large human-made mound at Huaca Prieta and nearby sites on the Pacific coast of northern Peru. Radiocarbon ages indicate an intermittent human presence dated between ~15,000 and 8000 calendar years ago before the mound was built. The absence of fishhooks, harpoons, and bifacial stone tools suggests that technologies of gathering, trapping, clubbing, and exchange were used primarily to procure food resources along the shoreline and in estuarine wetlands and distant mountains. The stone artifacts are minimally worked unifacial stone tools characteristic of several areas of South America. Remains of avocado, bean, and possibly cultivated squash and chile pepper are also present, suggesting human transport and consumption. Our new findings emphasize an early coastal lifeway of diverse food procurement strategies that suggest detailed observation of resource availability in multiple environments and a knowledgeable economic organization, although technologies were simple and campsites were seemingly ephemeral and discontinuous. These findings raise questions about the pace of early human movement along some areas of the Pacific coast and the level of knowledge and technology required to exploit maritime and inland resources.

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This study surveyed the mitochondrial haplotype diversity of nine freshwater fish species and two estuarine-marine species from the coastal basins and drainages of the highland plateaus of Paraná, Brazil. Portions of the cytochrome b gene or the control region were sequenced. The demographic history of each species was inferred using the Bayesian skyline method, mismatch distribution analysis and statistical neutrality tests. Demographic reconstruction analyses revealed a single pattern of variation in the effective population size (Ne ) among species. No dramatic changes in Ne were detected in upland species. By contrast, evidence of population expansion over the past 200 000 years was detected in all coastal plain and estuarine species. These findings correspond to periods of low sea-level (regressions) followed by a rapid increase in the sea-level by >100 m. The resulting reconnections and subsequent fragmentation and isolation between the estuarine and freshwater bodies were putatively relevant to the historical demography of the fish species in these areas.

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