VERTEBRATE TAPHONOMY OF TWO UPPER MIOCENE BONEBEDS IN WESTERN PROTO-AMAZONIA (SOLIMÕES FORMATION, BRAZIL): INSIGHTS FROM MACROVERTEBRATE AND MICROVERTEBRATE FOSSILS

ABSTRACT The Niterói and Talismã sites comprise two of the most important fossiliferous deposits of the Neogene in Brazil. After 30 years of research, these sites have revealed rich assemblages of vertebrates and provided a glimpse of the Amazonian fauna and environment during the Miocene. Despite this, detailed studies that attempt to explain the genesis of these bonebeds are still scarce and hamper more robust paleoenvironmental and paleoecological reconstructions. Here we provide the first in-depth taphonomic analysis for both locations. Sedimentological and taphonomic evidence suggest that the depositional environments of Niterói and Talismã were similarly represented by shallow and calm waters in lacustrine/swampy contexts. We propose that the accumulation of bones and teeth is the result of attritional (day-to-day) mortality of organisms of the local community in a low sedimentation environment. The thanatocoenosis was exposed to biostratinomic processes for longer periods of time, which explains the high disarticulation, disassociation, fragmentation and loss of skeletal elements. The almost absence of weathering indicates that the aquatic environment slowed down the organic degradation of bioclasts, while the rarity of abrasion shows a limited influence of hydraulic flows in transporting and remobilizing bioclasts. Thus, both sites preserve mostly autochthonous to parautochthonous bioclasts, with a moderate level of time-averaging. Our results corroborate the hypothesis that lentic environments can present remarkable preservational conditions for the formation of attritional accumulations of vertebrate remains. Moreover, we show how the different collecting methods affect the description of preservational features and taphonomic interpretations of both fossil assemblages.

Mid-Infrared Spectroscopy Supports Identification of the Origin of Organic Matter in Soils

Spectroscopic methods combined with statistics have recently gathered substantial interest in pedological studies. Near-infrared (NIR) spectroscopy has been utilized, for example, for reconstructions of the history and transformations of Chernozems, although no similar research was conducted based on mid-infrared (MIR). In this paper, the relevance of MIR spectroscopy was tested in studies on the origin/affinity of organic matter from chernozemic soils. Samples collected from three vegetation classes (grasslands, forests and arable lands) were investigated using MIR spectroscopy in order to create a statistical model, which was applied on buried profiles of unknown origin. The results showed a clear disjunction of vegetation classes. Samples of buried soil were placed in the space between all classes, indicating the relation to variable vegetation. Therefore, arable lands should not be omitted in paleoecological reconstructions, because we cannot exclude the cultivation of fertile soils before their burial. It was concluded that MIR methods may have similar applicability to NIR spectroscopy. Additionally, MIR spectra may also be discriminated according to the recognized soil type, which allows for direct reconstructions of the transformation trends in buried profiles.

The mesolithic Baigara human: mineralogical-geochemical studies, paleoecological reconstructions and history of early human migrations to Western Siberia

A modern human bone of the Mesolithic age, found for the first time in Western Siberia, was studied by the number of mineralogical-geochemical methods. Based on the results obtained, the conclusions about paleoecology, food types, and history of human migrations in the Late Pleistocene — Holocene in Siberia presented

A Connection Between the Settlement Dynamic of the Eastern Pamir and Paleoclimatic Changes in the Late Glacial and Holocene

This article is devoted to a review of the data on the chronology of the occupation of the Eastern Pamirs high-lands and the paleoecological reconstructions. At this moment it is known that there are two main episodes of the settlement of the region in the Final Pleistocene – Middle Holocene: 12–8 ka BP. (the main archaeological sites are the Istyk cave and the Kurteke grotto) and 8–6 thousand years ago (Oshkhona, Shakhty, Istykskaya cave, Kurteke). The review shows that these episodes coincide with the periods of the most favorable paleoclimatic conditions. The climate of the region in general is characterized as arid desert, with a predominance of open spaces of desert-steppe and desert appearance. The time intervals about 15–13 thousand years ago and about 9–8 thousand years ago are characterized with a transition from xerophilic groups to more mesophilic, which indicates a humidification of the climate during these periods. The researchers note that these climatic changes are likely to be pan-regional. The revealed cyclicality of climate changes in the Eastern Pamir region is comparable to archaeological data: the time intervals in when an increase in the climate humidity of the region is noted are similar to the intervals in when, according to archaeological data, the region was populated. Further paleoecological reconstructions of the Eastern Pamirs will reveal the connection between the cyclicality of climatic changes in the region and human settlement in its territory.

Potencial of rock-magnetic methods in paleoecological reconstructions: case study of Mikhailovtsement reference section (Ryazan region)

On the basis of detailed, combined rock-magnetic, lithological, and micropaleontological study of the Mikhailovtsement section of the Moscow syneclise (Ryazan region), the fluctuations in Central Russian Sea level in Callovian–Early Oxfordian were reconstructed. According to the variations of rock-magnetic parameters over the section, seven rock-magnetic intervals were established which correspond to different stages of basin evolution. These stages are compared with sea level fluctuations established on the basis of changes in the lithology of rocks and the ostracod complexes. In general, the nature of sea level change in Callovian–Oxfordian, revealed by combination of the methods during the study of Mikhailovtsement section coincides with global trend.

Review of the paleoecological reconstructions results for Western and Central Caucasus mountain lakes

This work is devoted to the study and classification of different transformation scenarios for Western and Central Caucasus lake ecosystems. In the course of work, more than 25 mountain lakes were examined and among them 4 model reservoirs the most promising from the point of view of paleoecological reconstructions were identified, which allowed us to allocate the most typical scenarios of lake ecosystems development in the region.