Paleontological Methods Research Articles

Editorial preface to special issue: Response of marine and terrestrial environments to Triassic–Paleogene hyperthermals

The Mesozoic–Paleogene hyperthermals represent critical intervals of rapid global warming associated with abrupt carbon cycle perturbations. These events can provide valuable deep-time insights into how climate might respond to the current rise in temperatures driven by anthropogenic greenhouse gas emissions. This special issue comprises 17 publications that cover a broad spectrum of the research on hyperthermals, and these can be grouped into four main themes: (1) carbon-cycle perturbations, (2) environmental changes and biogeochemical extremes, (3) biotic responses to warming, and (4) long-term climatic and environmental changes in greenhouse climates. By integrating sedimentological, geochemical, and paleontological methods, the studies in this issue explore carbon sources and release mechanisms, provide insights into the initiation, development, and termination of hyperthermal events, and elucidate their longer-term impacts. The studies provide new insights into the interactions between short-term extreme events and long-term climate trends, offering valuable perspectives on the future trajectory of Earth's climate in response to ongoing anthropogenic warming.

Upper Ordovician–Lower Silurian deposits in the Zakola section (Ilych River, Northern Urals): Composition, structure, formation environments

Research subject. Section of boundary deposits, exposed in the right side of the Zakola stream (the right tributary of the Ilych River, Northern Urals) with a total thickness of 98 m, presented with rock samples (more than 100 pieces), thin sections (100 pieces), slabs (10 pieces), and chemical analyses (15 pieces). Aim. Detailed description of the most complete section of the Upper Ordovician–Lower Silurian boundary sediments of the Shantym facies complex with a stratigraphic reference of layers, lithological typification of sediments, and restoration of sedimentation conditions. Methods. Conventional lithological and paleontological methods were used to dissect the section. Sampling was carried out after 1 m; however, samples were additionally taken when detailed observations were possible to identify lithological and facial differences. The thin sections were studied by the classic method of optical microscopy. The study of the fauna complex was carried out both by collecting samples of the author’s rocks and by the materials of A.I. Antoshkina. In addition, stock materials were attracted. Results. In the section, 14 packs of rocks were identified, which are represented by 6 lithological types of secondary dolomites. Their distribution along the section, along with the presence of characteristic faunal remains, made it possible to establish three members in the section, which can be correlated with the Katian, Hirnantian, and Ruddanian stages of the General Stratigraphic Scale. Conclusion. The Katian deposits are represented by the Yaptikshor Formation (Strata 1), which was formed under the conditions of the lower sublittoral of a ramp-type carbonate platform with a transgressive carbonate tract and a diverse fauna. The beginning of the Hirnantian (Strata 2) is characterized by shallow water conditions of the upper sublittoral up to the littoral, which reflects a sharp shallowing at the Katian–Hirnantian boundary and corresponds to the beginning of the global early Hirnantian regression. The rocks exposed higher up the section indicate sedimentation with a certain rise in the sea level; however, the correlation of this part of the section with the upper part of the Verkh Ruchey Formation is complicated by the fragmentary nature of the outcrops. The overlying Ruddanian deposits (Strata 3) were accumulated on the outskirts of a ramp-type carbonate platform under the conditions of the lower sublittoral, which corresponds to the beginning of the Early Silurian global transgression.

A comparative approach employing microCT for the analysis of Cenozoic foraminifera from the Brazilian carbonate equatorial platform

Worldwide, some of the largest hydrocarbon reservoirs are located in tropical neritic carbonate deposits. Biostratigraphic and paleoenvironmental analyzes of these sedimentary records are often based on the study of foraminiferal assemblage. Foraminifera-based biozones are widely employed in the oil industry to support drilling processes that, alongside petrophysical prospecting, define interval favorable for exploiting hydrocarbon resources. Both scientific research and the petroleum industry, however, usually apply traditional petrographical and paleontological methods to analyze microfossil assemblages, especially for large benthic foraminifera. New, faster, and more accurate methods based on microCT analyzes have emerged as a valuable high-output tool to obtain high-resolution microfossil records for biostratigraphy and paleoenvironmental reconstructions. This method is also useful for the development of digital databases for artificial intelligence applications. MicroCT analyzes, therefore, lead to faster identification of foraminifera assemblage and support digital access to international foraminifera repositories and reference collections, introducing a new dimension in micropaleontological research.

Lexical analysis of surveillance discourse in Iran's legal system; Emphasizing Foucault's paleontological method

Lexical analysis of surveillance discourse in Iran's legal system; Emphasizing Foucault's paleontological method

Early developmental stages of a Lower Ordovician marrellid from Morocco suggest simple ontogenetic niche differentiation in early euarthropods

Early developmental stages of euarthropods are exceptionally rare in the fossil record. This hampers our understanding of the biology, phylogeny, and development of this extremely diverse metazoan group. Herein, we use classical paleontological methods in combination with synchrotron X-ray microtomography to explore the morphology in ca. 480 million-year-old early developmental stages of the Lower Ordovician Fezouata Shale marrellid euarthropod. These stages range between 3.8 and 5.3 mm in length and are characterized by three distinct pairs of gently curved spines that projects from the head shield. The first pair of cephalic appendages are represented by uniramous antenullae of a sensory function. The second pair of cephalic appendages is robust, and had an anchoring or stabilizing function. The third cephalic appendage pair is composed of long cylindrical podomeres and was used for walking. The trunk appendages are biramous and consist of an endopod and a lamellate exopod. Two anterior trunk endopods are composed of long slender podomeres and were used for walking, while the more posterior trunk endopods bear robust endites and associated setae and were used for food gathering. The trunk of the earliest developmental stages is composed of thirteen segments, in contrast to more than 22 segments in the adult trunk. The similar appendage morphology and differentiation along the body is evident in adult individuals of the Fezouata marrellid, suggesting these different developmental stages shared similar methods of locomotion and food processing. Given that adults and juveniles are often preserved in the same or nearby sites, the niche differentiation between these life stages would be the result of the absolute smaller appendage size in immature stages compared to larger adults, effectively differentiating the size of food resources consumed by each. In addition, the delicate setae present in the posterior trunk appendages of early developmental stages might have been used to capture smaller food particles. This simple mode of ontogenetic niche differentiation might have been common in the early diverging euarthropod groups.

Geological expeditions and routes of M. Y. Lebedev: theoretical and practical results


 
 
 A set of geological expeditions and routes carried out by M. Y. Lebedev through- out his life was determined for the first time. The specified complex in the context of the set research purpose is analyzed. The purpose of the study is to identify and consider the main geological routes of expeditionary practice of the outstanding geologist M. Y. Lebedev and to generalize practically and theoretically the consequences of their implementation and its organizational activities in the field of geology. The study is based on a combination of theoretical provisions of geological research and the principles of application of the evidence base of historical and natural research. The main geological expeditions, in which M. Y. Lebedev took part, are studied and analyzed, their results are considered and generalized, and the organizational achievements of the scientist are clarified. It was found that the expeditionary practice gave Lebedev the opportunity to accumulate a complex of various geological materials, most of which were innovative. Each of these complexes became the basis for obtaining new theoretical results. The development and application of paleontological methods by M.Y. Lebedev were of particular importance. The method of stratigraphic paleontology developed by him allowed substantiating the new methodology of research of coal deposits of the Donetsk basin. The significance of Lebedev’s activity in the development of Azerbaijani oil production, in particular, the determination of the oil potential the Caspian Seabed near Baku, is pointed out. The cartographic activity of the scientist is described. The influence of M. Y. Lebedev on the formation of the geological service and higher geological education in Ukraine is estimated. The results of the study testified to the diversity of M.Y. Lebedev’s ex- peditionary practice and its role in his formation as a geologist of the European level; its significance in the development of theoretical and practical components of M.Y. Lebedev’s activity was determined, his formation as an organizer of geological research and higher geological education.
 
 

Марризм и советская фольклористика (по материалам архива М.К. Азадовского)

The linguistic theory of the Soviet academician Nikolai Marr which in the 1930s captured Soviet humanities, including literary and folklore studies, had several stages: from an unrestrained glorification up to its complete defamation in 1950 (after Stalin’s article in “Pravda”). Heated discussions around the “paleontological method” resumed in Russia during the Perestroika and later, when most experts consider it as unfounded. The present publication is focused on the remembered evidence of Mark Azadovsky (1888–1954) who in the 1930s headed all folklore studies in Leningrad (in the Academy of Sciences as well as at the University) and who was at that time deeply involved in the principal events of folkloristic life and was well acquainted with its participants. His letter to the Moscow folklore scholar Vera Krupyanskaya (1897–1985), written in May 1952, represents a retrospective evaluation of Marr’s direction in Soviet folklore studies and gives, moreover, an answer to the question: who among the Soviet specialists in folklore could be regarded (and to what degree) as a real adherent of Marr’s school? After 1949, when Mark Azadovsky was subjected to public dishonor and dismissed from all of his academic positions, he had no possibility to express his views in public. However, he managed to indirectly influence the contents of one of the “anti-Marrist” articles typical of that time (“About the fallacious views of N.Ya. Marr and his followers in the field of the folklore studies” by Vladimir Chicherov). The story of this article, published in the magazine “Soviet Ethnography” (1952) presents an “intrigue” with some fascinating details.

Keeping 21st Century Paleontology Grounded: Quantitative Genetic Analyses and Ancestral State Reconstruction Re-Emphasize the Essentiality of Fossils.

Simple SummaryOver the last two decades of biological research, our understanding of how genes determine dental development and variation has expanded greatly. Here, we explore how this new knowledge can be applied to the fossil record of cercopithecid monkeys. We compare a traditional paleontological method for assessing dental size variation with measurement approaches derived from quantitative genetics and developmental biology. We find that these new methods for assessing dental variation provide novel insight to the evolution of the cercopithecid monkey dentition, different from the insight provided by traditional size measurements. When we explore the variation of these traits in the cercopithecid fossil record, we find that the variation is outside the range predicted based on extant variation alone. Our 21st century biological approach to paleontology reveals that we have even more to learn from fossils than previously recognized.Advances in genetics and developmental biology are revealing the relationship between genotype and dental phenotype (G:P), providing new approaches for how paleontologists assess dental variation in the fossil record. Our aim was to understand how the method of trait definition influences the ability to reconstruct phylogenetic relationships and evolutionary history in the Cercopithecidae, the Linnaean Family of monkeys currently living in Africa and Asia. We compared the two-dimensional assessment of molar size (calculated as the mesiodistal length of the crown multiplied by the buccolingual breadth) to a trait that reflects developmental influences on molar development (the inhibitory cascade, IC) and two traits that reflect the genetic architecture of postcanine tooth size variation (defined through quantitative genetic analyses: MMC and PMM). All traits were significantly influenced by the additive effects of genes and had similarly high heritability estimates. The proportion of covariate effects was greater for two-dimensional size compared to the G:P-defined traits. IC and MMC both showed evidence of selection, suggesting that they result from the same genetic architecture. When compared to the fossil record, Ancestral State Reconstruction using extant taxa consistently underestimated MMC and PMM values, highlighting the necessity of fossil data for understanding evolutionary patterns in these traits. Given that G:P-defined dental traits may provide insight to biological mechanisms that reach far beyond the dentition, this new approach to fossil morphology has the potential to open an entirely new window onto extinct paleobiologies. Without the fossil record, we would not be able to grasp the full range of variation in those biological mechanisms that have existed throughout evolution.

Biogenic origin and structure of dome-shaped microstructures - calyptras in the Upper Ordovician limestones from the central part of the Gorny Altai

Calyptras are the smallest biogenic structures were found from the Upper Ordovician "Azratkan" Section in the Anui-Chuya structural facies zone. The petrographic and paleontological methods were applied to study caliptra’s internal structure and the host rock. It was found that bacterial-cyanobacterial associations took part in the calyptras development. The species Hedstroemia halimedoidea Rothpletz was identified in the space between calyptras and described.

SOME ASPECTS OF POLISH-UKRAINIAN GEOLOGICAL AND GEOMORPHOLOGICAL RESEARCHES OF WESTERN VOLYN-PODILLIA DURING THE POLISH INVASION

The proposed article is based on an analysis of publications on field observations published in the then Polish and Ukrainian periodicals, collections of materials from scientific forums at various levels, works collections of individual Polish and foreign scientific institutes, etc. The purpose of the article was an attempt to analyze and generalize the research results of the study area in the field of Quaternary geology and geomorphology. It should also be noted that publications from the listed sections of physical geography are encountered quite sporadically and in significantly smaller numbers than articles on purely geological disciplines such as mineralogy, petrography, lithology, tectonics, etc. The study of geological and geomorphological objects and processes was carried out on the territory of Western Volyn-Podillia, which at that time was a part of the Polish-Lithuanian Commonwealth. The works mainly concerned the study of the stratigraphy of anthropogenic sediments distributed in the Podillia loess and loess soils, continental glaciations and related glacial and fluvial-glacial deposits, surface and underground karst, etc. It was established that significant in volume and depth of generalization of works on the geological and geomorphological structure the region features at that time was not. The studies that were carried out were not systematic, they were often carried out on the researchers initiative and without adequate funding, with localization mainly in the territory with open at that time deposits of certain minerals types. Analysis of publications can be stated as follows: the study of Quaternary deposits of the region and loess in particular was carried out with extensive use of laboratory studies, paleontological method, chemical, particle size distribution mineralogical and petrographic analyzes, the method of separation of loess minerals in heavy liquids, paleontological and archaeological observations, etc., were progressive at that time. It should be noted that individual reports on the determination of the age of the Quaternary strata were poorly synchronized with each other and a reliable generally accepted scale for the division of these deposits in this period was not agreed. During this period, factually substantiated schemes of geomorphological zoning of both the Podillia region as a whole and its individual components were proposed. Regular relationships of the relief features of the region with the lithogenic base, neotectonic movements, glacial and fluvial-glacial processes are traced. Significant progress is noted in the study of stratigraphy, lithology of local loess strata, problematic issues of their genesis are discussed. Among the few works on the study of the loess cover of Volyn-Podillia, the work of Yu. Polianskyi and Yu. Tokarskyi attracts attention first of all. The works on the study of loess are important due to: a) their almost ubiquitous distribution in the described territories; b) value for stratigraphic subdivision of the Pleistocene; c) controversial genesis; d) widespread use for the production of bricks and tiles. Work on the study of surface and underground forms of the Podillia karst has spread. Systematic mapping of individual underground cavities begins which gave impetus to their use in the future as objects of tourism. The largest number of works is devoted to the problems of studying the relief and modern physical and geographical processes in the interwar period. At the same time, along with purely descriptive publications, works appear where conclusions are based on the use of cartographic materials, which allowed researchers to identify significant patterns in the morphological features of the region. In the period under study, numerous publications by soil scientists also appeared, in which Quaternary sediments are considered as parent rocks on which soils were formed, the dependence of the type of soil on the lithology of the underlying rocks is established.
 In general, the works of Polish and Ukrainian researchers in the characterized period laid a reliable foundation for modern ideas about the geological and geomorphological features of the region.
 Keywords: geomorphological studies, Quaternary deposits, glacial deposits, stratigraphy, morphology, loess deposits.

Kenozoické sedimenty v lomu Předklášteří u Tišnova

In the multi-level quarry Předklášteří near Tišnov exploiting medium-grained biotite metagranite of the Brunovistulicum, up to 30 m thick unconsolidated sediments, were studied recently at the top of excavation. These sediments are exposed at the two top quarry levels. During the exploration work in 1965, these sediments were not encountered, because today’s quarry mining area has already exceeded the original considerations about the extent of mining.The altitude of the erosive base of these fluvial or deltaic sediments 370–375 m indicates their pre-Quaternary age. Our research was focussed on the Lower Miocene part of the sediments tentatively considered as lake, delta or river sediments. Sediments were studied by sedimentological, petrographic, mineralogical, geochemical and paleontological methods. Preliminary results from overlaying Quaternary sediments did not allow definite stratigraphical interpretation.Geochemical analyses of silty clays to claystones were compared with the occurrences of similar sediments from Brno and its surroundings (Kamechy, Kohoutovice, Obřany, Svinošice). These analyses proved that the sediments underwent a short transport of several kilometres and could be derived from weathering residues of the rocks forming the surrounding Brunovistulicum.Our research has confirmed the affiliation of sediments in top of the sequence to the Pleistocene colluvial deposits. Sediments found in the lower part of the layered sequence, trapped along the fault of the E–W direction, were assigned stratigraphically to the Lower Miocene (Ottnangian).

EXPERIENCE IN APPLYING EXPERT ANALYSIS AND RANK CORRELATION DURING GEOLOGICAL AND FORECASTING WORK ON HYDROCARBONS

Problem Statement and Purpose. The diverse and extensive geological materials and geophysical data used in forecasting and prospecting operations for oil and gas exploration within the Black Sea’s northwestern shelf are usually interpreted in a complex manner. This complexity, however, is often spontaneous and fragmentary, with no new theoretical concepts taken into account. For example, the theory of global fluidogenesis represents an alternative hypothesis to the organogenic-sedimentary formation of hydrocarbon deposits but is commonly not considered. The authors of this article believe that the complexity should be replaced by a method of directed rank interpretation of geological information, in which ranking distinguishes the maximum information on one of the sections of geological work with regard to its completeness and consistency. The purpose of this study is to apply expert analysis and rank correlation of obtained information to geological and forecasting research on hydrocarbons. To achieve this goal, two basic principles, rank and direction, are considered. The data include seismic, tectonic-geodynamic, lithological, geochemical, mineralogical, and meiobenthic characteristics of the sea bottom scaled according to their sensitivity to the independent variable, i. e., hydrocarbons. Study area, material, and methods. The Pradneprovskaya area has been chosen for analysis. It is a promising location for oil and gas exploration in the shallow part of the inner northwestern shelf of the Black Sea. Geologically, this is the area of junction for the South Ukrainian monocline with the system of blocks included in the Predobrudzha-Crimean riftogenic trough. The area was studied by geophysical, geochemical (hydrocarbon gases, liquid hydrocarbons), mineralogical (X‑ray diffraction of clay minerals, thermobarogeochemistry of inclusions in minerals), and paleontological (foraminifera, nematodes, ostracods) methods, along with the drilling of a deep (2352 m) parametric well (Pradneprovskaya‑2). Results. It is shown that expert analysis of the diverse information within the framework of selected tasks, which are poorly formalized into a single system, provides the basis for an effective method of comparing information databases formed on different principles. This analysis is founded on the principle of directed (vector) ranking, where each rank narrows the search area and becomes more sensitive to the hydrocarbon deposit. The article gives an example of how this method can be used for a specific objective in its entirety, namely: (a) selection of information ranks (parameters), (b) selection of experts, (c) calculation of the rank matrix, (d) determination of hierarchical dependencies of ranks, (e) verification of the matrix, and (e) calculation of the concordance coefficient. The obtained results indicate that the proposed method of expert analysis with rank correlation under modern conditions using diverse geological materials that are not formalized into a single database, provides high reliability in the comprehensive interpretation of data. The method will help optimize geological and forecasting research on hydrocarbons within the Black Sea shelf.

About the remains of Ichthyosaurs of the genus Nannopterigius from the Late jurassic of West Kazakhstan region

About the remains of Ichthyosaurs of the genus Nannopterigius from the Late jurassic of West Kazakhstan region. This article discusses the discovery of the remains of an ichthyosaur of the genus Nannopterygius from the territory of the West Kazakhstan region of the Republic of Kazakhstan. As scientific researches show, fragments of skeletons of representatives of the genus are often found in deposits of the Late Jurassic at the site of Pogodaevo of the Baiterek district of the West Kazakhstan region. Described specimen has various diagnostic features of the structure of individual skeletal fragments (width of the interclavicle platform, length-to-width ratio of the coracoid, width of the distal end of the scapula). The aim of the study is to study the variability in the structure of skeletal fragments based on new finds of an ichthyosaur of the genus Nannopterygius (Yasykovia). In this article, the generally accepted paleontological methods of field and desk research were applied: the standard method of working with paleontological material to extract the studied samples from the host rock; morphological and morphometric analysis of fossils during species diagnostics. The presence of ichthyosauric remains similar to the holotype Nannopterygius (Yasykovia) yasykovi has been confirmed in the Jurassic deposits of the Republic of Kazakhstan. Material from Nannopterygius (Yasykovia) shows significant individual variability in skeletal structure. The age of the find belongs to the Late Jurassic, Upper Volga sub-stage, Epivirgatites nikitini zone Key words: Nannopterygius (Yasykovia), Western Kazakhstan, Late Jurassic, Upper Volga substage.

On subfamily structure of the Cupedidae (Coleoptera, Archostemata): data from paleontology and an approach to solving conflicting classifications

This paper demonstrates some of main differences between the systematic constructions based mostly on paleontological research and constructions involving the other approaches. Some reasons for these differences are discussed, together with an approach to solve contradictions between the conflicting hypotheses. The multiple (multidimensional) parallelism gives a possibility to solve many problems of phylogenetic interrelations due to reconstructions based on coincidence of patterns of changes (series of interconnected facts) traced in different aspects of evolutionary processes. This principle originates in the ideas by Jean Agassiz and Ernst Haeckel defined as the principle of triple parallelism. Other aspects of the evolution can be added to the morphology, embryology, and paleontology, initially included in this method. The molecular method is one of such aspects. It is shown that the potential resolution of the morphological and molecular approaches in some cases could be rather restricted, particularly applying ancient groups with main evolutionary transformations passed far in the past. The infraorder Cupediformia and suborder Archostemata in general are examples of such cases. It is advisable in the current research period that has followed the previous interpretation of the systematic structure of the family Cupedidae recognizing three subfamilies with not quite distinct hiatus between them (Cupedinae, Ommatinae and Triadocupedinae). Some recent morphological and molecular approaches proposed to divide the Cupedidae into two separate families on the basis of incomplete information accessible after study of only modern representatives, as most events in the family evolution occurred during the Palaeozoic and Mesozoic, and these events are scarcely possible to trace without considering fossils. As the principle of multiple parallelism cannot be currently used for archostematans to the full extent of its power, it is necessary to choose the paleontological method of phylogenetic reconstruction as crucial. This approach is preferable for groups that are well-documented through very diverse fossils, and for which only few of its remnants of the past diversity reached the modern epoque.

About finding of mesozoic reptiles in the Republic of Kazakhstan

he article is devoted to the description of a new representative of the family Undorosauridae, found on the territory of the West Kazakhstan region. A new genus of ichthyosaurs of the family Undorosauridae has been identified. The main diagnostic features of this family are incomplete medial fusion of the sciatic and pubic bones, as well as a peculiar structure of the skull (large nasal opening, oval eye socket, wide occipital part and the structure of the occipital part. In this work, we applied the generally accepted paleontological methods of field and laboratory research: standard procedure for working with paleontological material to extract the studied samples from the host rock; morphological and morphometric analysis of fossils in species diagnostics. The similarity in the structure of the skull, postcranial skeleton, belts, limbs allows us to attribute the described ichthyosaur skeleton to the family Undorosauridae. Geological age: late Jurassic, Middle Volga tier, Zaraiskites Zarajskensis zone.

Орал өзенінің (Жайық) төменгі ағысы аумағынан оңтүстік пілінің archidiskodon meridionalis gromovi жаңа тістерін табу туралы

Molars of the southern elephant Archidiskodon meridionalis gromovi were found in alluvial deposits near Uralsk (West Kazakhstan region, Republic of Kazakhstan). In this work, were applied generally accepted paleontological methods of field and cameral research: standard methods of working with paleontological material for extraction of samples from the host rock; morphometrically morphological analysis of fossil remains in the species diagnosis. Have been studied a series of teeth of M3/m3 shifts of chronologically successive subspecies of Archidiskodon meridionalis from paleopleistocene (middle villafrancian) localities in Western Kazakhstan. Analysis of the characteristics of teeth (frequency of plates, length of one plate, number of plates, enamel thickness, hypsodont index, crown proportion index) showed that the studied indicators are close to those characteristic of Archidiskodon [Elaphas] meridionalis gromovi. For the studied tooth changes, the parameter of the length of one plate turned out to be very diagnostic. The limits of variation in the size of the crown of teeth in different subspecies largely coincide.

Subsidence and maturation evolution of a new lower-slope minibasin, Xingning Sag, northern South China Sea

Study of Subsidence and maturation evolution of a continental slope basin without a drilled well is an important problem in the early stage of deep-water exploration. Lack of some parameters, such as stratigraphic-age, porosity-depth relationship, exact paleo-water depth and heat flow value are common problems in the study of subsidence and maturity history. Using 46 long 2D seismic lines and paleo-water depth data from paleontological data of a well on the slope toe, the present study combines backstripping with thermal modeling to reconstruct the subsidence and maturation evolution of a lower-slope minibasin, Xingning Sag (XS), on the southeast Pearl River Mouth Basin (PRMB) of the South China Sea (SCS), now a new prospecting area. Stratigraphic-ages, porosity-depth relationship, lithology of XS were estimated using data from an adjacent basin. Paleo-water depths were obtained by clinoform geometry using seismic facies and paleontological method. With these parameters, the subsidence curves were created by backstripping. Crustal stretching factors (β) were obtained by best fit of tectonic subsidence curve and thermal modeling. With these stretching factors, the theoretical subsidence and heat flow values were obtained at the same time. Based on the heat flow value and the backstripping parameters, the maturation history of this basin was simulated. The result shows XS evolved through three cycles of subsidence during 46–23.03 Ma, 23.03–13.82 Ma and 13.82–0 Ma, respectively. Each cycle shows a rifting phase of relatively rapid tectonic subsidence followed a cooling phase of slow subsidence. Potential Eocene lacustrine source rocks are distributed primarily in the central depression area (Xingning main sub-sag), and would have entered the main oil-generation window and main gas generation during early- and mid-Miocene respectively.

The first postcranial oreodont (mammalia, Artiodactyla, Merycoidodontidae) skeleton from Mexico: Description and paleobiological significance

In this study, the first postcranial skeleton of an oreodont (Merycoidodontidae, Artiodactyla) found in Mexico is described and discussed. This family was very successful, quasi endemic of North America, and lived from the Late Duchesnean North American Land Mammal Age, acronymed NALMA (Late Eocene) to the Late Hemphillian NALMA (early Late Miocene), roughly between 38 Ma to 5.2 Ma. Oreodonts were diverse (~27 genera, 69 species), and fairly abundant. However their record in Mexico is modest: two genera in northeastern Chihuahua (Rancho Gaitán local fauna, Late Duchesnean), one genus in Aguascalientes (Zoyatal local fauna, early Hemingfordian), one genus in northwestern Oaxaca (Yolomécatl local fauna, latest Uintan-earliest Duchesnean) and one genus in central Oaxaca (Suchilquitongo local fauna, latest Arikareean-Early Hemingfordian). Therefore, the finding in Tehuitzingo, southern Puebla of an articulated postcranial skeleton referred to the Merycoidodontidae, described below, is quite important and significant.The fossil material was recovered from the Tehuitzingo Formation, which largely fills the namesake basin; such geologic unit is a thick lacustrine-fluvial, fine-grained, indurated sequence that includes strata of silicified limestone and siltstone/sandstone interbedded by tuff/ignimbrite sheets, one of them yielded a K-A date of 29.9 ± 0.8 Ma (Early Oligocene), confirmed by the 29.96 Ma age of the overlying Puerto El Gato Formation. The fossil locality lies near Atopoltitlán, and yielded a medium-sized mammalian, articulated, postcranial skeleton. The recovery, preparation and study of the material were performed using standard paleontological methods and techniques. The fossil exhibits among others, the following features: Antero-posteriorly wide ribs, astragalus with double trochlea, ecto- and mesocuneiform fused, phalanx II smaller than the others, and hoofed ungual phalanges. Such characters set it in the artiodactyl Family Merycododontidae, making it the first of its kind in Mexico. The size of the postcranial skeleton corresponds to that of the Whitneyan-Late Arikareean Eporeodon; however, the lack of skull and jaws prevents a positive assignment to this or other merycoidodont genus.Finally, the Tehuitzingo species was tropical, probably cursorial, (?herding), and lived in an open country ecologic setting, with ready access to water supply. Unusual taphonomic conditions led to its preservation as an articulated, headless carcass.

Динамика палеолитических индустрий Алтая по археологической летописи Денисовой пещеры

Today, Altai has the most insightful archaeological sites reflecting the ancient history of the vast space spanning from the Ural Mountains to the Pacific Ocean and from Mongolia to the Arctic Ocean. The most engaging findings in the study of the primitive period were obtained in the North-Western part of Altai based on the materials of a crosscutting study of multilayer Paleolithic sites in the valley upstream of the River Anuy. The longest cultural timeline was stu­died in Denisova Cave. Analysing the Pleistocene cave deposits, the researchers applied a number of modern methods in archeology, stratigraphy, lithology, paleontology, geochronology, and other related sciences. Besides cave deposits with numerous artefacts, they discovered extensive paleontological materials, which helped to trace the evolution of cultural traditions from the primitive period to the end of the Paleolithic era and reconstruct the living conditions of the primitive human beings across the paleogeographic stages of the Pleistocene. The latest anthropological discoveries in the cave are associated with the core issues in the development of Homo genus and the formation of modern man.

Seasonal and interannual changes in planktic foraminiferal fluxes and species composition in Guaymas Basin, Gulf of California

Abstract Paleoclimate records based on planktic foraminifera shells are reliant upon an understanding of how populations respond to annual and interannual changes in surface hydrography. In particular, annual and interannual flux variability would be expected to impact the interpretation of geochemical proxies from foraminifera shells. A seven-year time series from Guaymas Basin, Gulf of California reveals a seasonal progression of foraminiferal species flux, with faunal assemblages characteristic of winter, summer, and fall conditions. Observations of flux along with remotely sensed sea surface temperatures and previously published oxygen isotope data are used here to assess the range of environmental conditions each species would be expected to represent in the fossil record. We find that both species abundances and phenology are altered during negative El Nino Southern Oscillation (ENSO) phases, as occurred over the course of the study period. This observation is used in conjunction with published δ18O data to subsample fluxes in simulation of assemblages collected and analyzed by standard paleontological methods. This approach indicates that during periods more influenced by El Nino conditions, Globigerina bulloides would record warmer conditions, while Neogloboquadrina dutertrei would reflect cooler conditions.