Hasil untuk "Paleontology"

Silvio Renesto, Cinzia Ragni, Fabio Magnani

Abstract A new virtually complete specimen of the eosauropterygian nothosauroid Lariosaurus valceresii is described. The specimen was collected in the Kalkschieferzone of the Meride Limestone (Ladinian, Middle Triassic) in the UNESCO World Heritage area of Monte San Giorgio (Switzerland/Italy). The new specimen is the first L. valceresii collected in Switzerland and the first known Lariosaurus specimen with remains of the skin. The skin is preserved as a carbon film revealing the shape of the scales. It outlines the body and limbs, showing that the hands and feet were webbed. The skin is present postaxial to both the humeral shafts and the anterior portion of the trunk suggesting the possible presence in life of large and very strong retractor muscles for the forelimbs indicative that Lariosaurus could have performed a paraxial, otariid-like, "flying-rowing" swimming for rapid acceleration.

Fujiang Liu, Jiahong Wu, Yichen Dong et al.

Summary: Polyploidy, the duplication of the entire genome, is a major force in vertebrate evolution, yet how new polyploid species survive and prosper remains unclear. Here, we present a chromosome-level genome of the cyprinid Spinibarbus caldwelli, whose allotetraploid event is dated to ∼4 million years ago based on transposable element distributions in its two subgenomes. Genomic analyses reveal unique patterns of homoeologous exchanges between the two subgenomes, indicating a gradual evolutionary process prior to their suppression. Furthermore, we identify a striking pattern of accelerated evolution of RNA-binding proteins across independently evolved tetraploid cyprinids. Functional assays of one such protein, Tia1, demonstrate that the tetraploid orthologs may be more efficient at stress granule disassembly than those of diploid relatives. These findings suggest that improved cellular stress management, particularly in RNA processing, might be a key adaptation that has enabled the evolutionary success of polyploid cyprinids.

Karolina Maciejewska, Małgorzata Latałowa, Dominika Kunicka et al.

During the archaeological exploration of two Lusatian Urnfield Culture settlements, dated to the Early Iron Age and located in north-central Poland, 11 well-preserved clay vessels filled with waterlogged botanical remains were discovered. Their position and context led archaeologists to suggest a possible function of these vessels as foundation offerings. Accordingly, the results of archaeobotanical analyses were discussed within this context. The qualitative and quantitative richness of the subfossil samples collected from these vessels also offered an opportunity to provide data on the vegetation that developed in the vicinity of both settlements. This study focuses on grassland vegetation as a contribution to the broader history of grasslands in different European regions. The potential and limitations of reconstructing ancient vegetation and land use from archaeobotanical material of complex origin are also discussed.

L. David Carter, Donna Christensen, David M. Hopkins et al.

Motivated by the need for more paleodata for Pliocene paleoclimate data-model comparison, we revisited unpublished investigations of a fossiliferous site on the Niguanak River in Arctic North America. Analyses of the samples indicates forested conditions during an early phase of sedimentation in which environments were perhaps similar to those near tree line in the modern Anchorage area or farther south along the Pacific coast, whereas during a later phase of sedimentation, environments were characterized by shrub tundra vegetation and were possibly similar to the present-day conditions in the interior of southern Seward Peninsula. We describe the site stratigraphy and discuss the macrofossils and pollen recovered from the sediments, their paleoecological implications, and their significance for paleoclimate and sea ice. Mean annual temperatures were found to be 12.7°C warmer than current, with a pattern of much warmer winters, and less difference in summer warming as observed at other Pliocene Arctic sites. Finally, we discuss possible age assignments for the sediments, based on regional stratigraphy and geomorphology, and the probable sequence of evolution of arctic borderland climate and ecosystems.

Neil J. Tabor, John Geissman, John Geissman et al.

The Whitehorse Group and Quartermaster Formation are extensive red-bed terrestrial sequences representing the final episode of sedimentation in the Palo Duro Basin in north-central Texas, U.S.A. Regionally, these strata record the culmination of a long-term regression sequence beginning in the middle to late Permian. The Whitehorse Group includes beds of abundant laminated to massive red quartz siltstone to fine sandstone and rare dolomite, laminated to massive gypsum, and claystones, as well as diagenetic gypsum. The Quartermaster Formation exhibits a change from nearly equal amounts of thin planar and lenticular fine sandstone and laminated to massive mudstone in its lower half to overlying strata with coarser-grained, cross-bedded sandstones indicative of meandering channels up to 7 m deep and rare overbank mudstones. Paleosols are absent in the Upper Whitehorse Group and only poorly developed in the Quartermaster Formation. Volcanic ash-fall deposits (tuffs) present in uppermost Whitehorse Group and lower Quartermaster Formation strata permit correlation among five stratigraphic sections distributed over ∼150 km and provide geochronologic age information for these rocks. Both the Whitehorse Group and Quartermaster Formation have traditionally been assigned to the late Permian Ochoan (Changhsingian) stage, and workers assumed that the Permian-Triassic boundary is characterized by a regionally significant unconformity. Chemostratigraphic or biostratigraphic evidence for this age assignment, however, have been lacking to date. Single zircon U-Pb CA-TIMS analyses from at least two distinct volcanic ash fall layers in the lower Quartermaster Formation, which were identified and collected from five different localities across the Palo Duro Basin, yield interpreted depositional ages ranging from 252.19 ± 0.30 to 251.74 ± 0.28 Ma. Single zircon U-Pb CA-TIMS analyses of detrital zircons from sandstones located only a few meters beneath the top of the Quartermaster Formation yield a range of dates from Mesoproterozoic (1418 Ma) to Middle Triassic (244.5 Ma; Anisian), the latter of which is interpreted as a maximum depositional age, which is no older than Anisian, thus indicating the Permian-Triassic boundary to lie somewhere within the lower Quartermaster Formation/upper Whitehorse Group succession. Stable carbon isotope data from 180 samples of early-burial dolomicrite cements preserve a chemostratigraphic signal that is similar among sections, with a large ∼−8‰ negative isotope excursion ∼20 m beneath the Whitehorse Group-Quartermaster Formation boundary. This large negative carbon isotope excursion is interpreted to be the same excursion associated with the end-Permian extinction and this is in concert with the new high precision radioisotopic age data presented and the fact that the excursion lies within a normal polarity stratigraphic magnetozone. Dolomite cement δ13C values remain less negative (between about −5 and −8 permil) into the lower part of the Quartermaster Formation before becoming more positive toward the top of the section. This long interval of negative δ13C values in the Quartermaster Formation is interpreted to represent the earliest Triassic (Induan) inception of biotic and ecosystem “recovery.” Oxygen isotope values of dolomicrite cements show a progressive trend toward more positive values through the boundary interval, suggesting substantially warmer conditions around the end-Permian extinction event and a trend toward cooler conditions after the earliest Triassic. Our observations on these strata show that the paleoenvironment and paleoclimate across the Permian-Triassic boundary in western, sub-equatorial Pangea was characterized by depositional systems that were not conducive to plant preservation.

CHAN-GYU YUN, GALADRIEL FREEMAN PETERS, PHILIP JOHN CURRIE

Tarbosaurus bataar is a sister taxon of the well-studied theropod dinosaur Tyrannosaurus rex, and numerous fossils of this tyrannosaurid have been discovered in the Upper Cretaceous Nemegt Formation of Mongolia. Although specimens of different sizes of Tarbosaurus bataar have been discovered since its initial description, few rigorous studies on its growth changes have been done. Here we examine growth changes in the frontal bones of seven Tarbosaurus bataar specimens using bivariate analyses and the Björk superimposition method to demonstrate trends in their ontogenetic allometry. The width and depth of the frontal undergoes positive allometry during growth, whereas the length shows a trend of negative allometry. The details of growth changes in Tarbosaurus bataar frontals are largely similar to those of Tyrannosaurus rex. Furthermore, generic allometric trends of tyrannosaurid frontals, including those of Tarbosaurus bataar, are shared with other large-bodied theropod clades and may represent a consequence of strengthening parts of the braincase as an anchor for the jaw musculature.

Łucja Fostowicz-Frelik, Sergi López-Torres, Qian Li

Abstract Ischyromyids are a group of large rodents with the earliest fossil record known from the late Paleocene (Clarkforkian) of North America; they are considered the earliest fossil representatives of Rodentia of modern aspect. Ischyromyids dominated early Paleogene small-mammal assemblages of North America and in the latest Paleocene migrated to western Europe and to Asia; in the latter they survived only to the beginning of the late Eocene, but were never abundant. Here we describe for the first time the calcanei of ischyromyids from the early middle Eocene of the Erlian Basin in Nei Mongol, northern China. These calcanei document the existence of three species. The morphology of the studied tarsal bones overall suggests ambulatory locomotion for these animals (‘slow cursors’), similar to that of the coypu and porcupines, but one form shows more marked cursorial capabilities. These differences show that Chinese ischyromyids, although rare, had attained greater taxonomic diversity by the middle Eocene in Nei Mongol than estimated from dental remains. We also address the question of the morphological and ecological divergence of these ischyromyids in relation to their North American counterparts, as well as the issue of a direct dispersal route from North America to Asia in the early Eocene.

Fernando A. Ferratges, Samuel Zamora, Marcos Aurell

Semi-articulated paguroids are rare fossils, and there are only few records from Cenozoic strata. Here we present a new and exceptionally preserved hermit crab (Diogenidae) from the Eocene of Huesca (Spain) that preserves the anterior part of the carapace, together with appendages. Diogenes augustinus sp. nov. represents one of most completely preserved hermit crabs known to date, providing crucial information to understand the evolution of the family Diogenidae. It is characterized by poorly marked regions of shield, absence of Y-line and markedly unequal and robust chelipeds. The specimen is preserved out of its host shell suggesting rapid burial in siliciclastic strata of a prodeltaic environment.

Béla Török, Péter Barkóczy, Árpád Kovács

In the last period, several projects were initiated in the field of examination of artefacts because of the development of the materials testing equipment and methods. This research work gave new results on the historical studies and the technological levels of different ages. The examination of metallic artefacts has a great importance in this work. The answers to our questions on the structure of metals are continuously searched for by means of new measurement methods. Optical microscopy and classic metallography have a significant role in the research projects of the mentioned area. Nowadays it is not necessary to use complicated etching methods to study the different metallographic phases. SEM-EDS studies of the same sample provide information on the chemical composition of the phases, and it is possible to examine the structure at higher magnification. This study summarizes the amount of information obtained from the project, and the practice of the Archaeometallurgical Research Group of the University of Miskolc (ARGUM), based on these measurement methods. Selected examples are used to show the in-depth analysis of the microstructure. Metallography is a destructive material testing method, as samples must be taken from the artefacts. Questions of heritage protection and restoration arise. In all cases, the balance between the amount of information and the restoration or protection must be considered.

Seung Choi, Seokyoung Han, Noe-Heon Kim et al.

The Gekkota is an important clade in the evolution of calcified eggshells in that some of its families lay rigid eggshells like archosaurs. However, the fundamental differences and similarities between the mechanism of rigid eggshell formation of the Gekkota and Archosauria have not been investigated thoroughly due to the lack of knowledge of gekkotan eggshells. Here, we report for the first time a comprehensive analysis of morphological, chemical compositional, and crystallographic features of rigid and soft gekkotan eggshells. Exhaustive morphological description provided common characters for gekkotan eggshells, as well as unique features of each species. We found that elemental distribution of rigid gekkotan eggshells is different from that of avian eggshells, especially in the case of Mg and P. In addition, the crystallographic features (size, shape, and alignment of calcite grains) of gekkotan eggshells are completely different from those of archosaur eggshells. The result of this study suggests that soft gekkotan eggshells are morphologically more similar to tuatara eggshells rather than soft eggshells of derived squamates. The chemical compositional analysis suggests that the eggshell may act as a mineral reservoir for P and F as well as Ca. More importantly, all chemical compositions and crystallographic features imply that the gekkotan eggshell formation may begin at the outer surface and growing down to the inner surface, which is opposite to the direction of the archosaur eggshell formation. This character would be crucial for identifying fossil gekkotan eggs, which are poorly known in paleontology. All these lines of evidence support that soft gekkotan and tuatara eggshells share the primitive characters of all lepidosaurid eggshells. Finally, gekkotan and archosaur rigid eggshells represent a typical example of convergent evolution in the lineage of the Sauropsida.

Damborenea, Susana E.

Numerosos trabajos regionales o locales han propuesto el reconocimiento de unidades biogeográficas de distintos rangos (biocoremas) basadas sobre la distribución de los moluscos bivalvos para el Jurásico, pero no existía una síntesis a nivel mundial. Este trabajo es una revisión de las más significativas de esas propuestas, en un intento de lograr una síntesis de los patrones biogeográficos globales desde el Jurásico Temprano al Tardío, mientras se producían cambios sustanciales en la paleogeografía de la Tierra y los patrones de circulación oceánica como resultado de la disgregación de Pangea. Se hace también un breve análisis de la evolución en el tiempo y el espacio de cada una de las principales unidades reconocidas y de sus relaciones. Estos biocoremas pueden agruparse en tres unidades de primer orden que han tenido continuidad en el tiempo: Boreal, Tethys y Austral. Las unidades revisadas aquí han sido reconocidas y caracterizadas de forma muy heterogénea por los distintos autores, pero los criterios básicos más utilizados incluyen desde el grado de endemismo y la diversidad relativa, hasta las afinidades paleobiogeográficas de los taxones a nivel genérico. Los patrones de distribución de los bivalvos jurásicos no solamente son claves para entender cuestiones puramente biogeográficas, sino que han sido utilizados como argumento y evidencia en discusiones de índole paleogeográfica (como el establecimiento de corredores oceánicos, o patrones de circulación marina superficial), e incluso son pruebas de peso para la discusión de tópicos paleotectónicos, como la localización de terrenos desplazados y la deriva continental.

Gerard R. Case, Todd D. Cook, Eric M. Saford et al.

A diverse selachian fauna was collected from the Island Creek Member of the Peedee Formation at Castle Hayne, New Hanover County, North Carolina, USA. This inner neritic assemblage consists of 23 species from eight orders, 17 families, and 20 genera and includes the new species Ptychotrygon clementsi sp. nov.  The dentition of a few large macrophagous species with large palaeobiogeographical ranges is described. However, the majority of the reported specimens belong to relatively small species that are endemic to the southern regions of the Western Interior Seaway and the Atlantic and Gulf Coastal plains of North America.

Markus Pracht, Ian D. Somerville

An integrated study of borehole data and outcrop of Mississippian (late Tournaisian to late Viséan) rocks in Co. (County) Galway, western Ireland has enabled a more detailed geological map and lithostratigraphy to be constructed for the region. Several carbonate formations have been distinguished by microfacies analysis and their precise ages established by micropalaeontological investigations using foraminifers and calcareous algae. In addition, palaeogeographic maps have been constructed for the late Tournaisian, and early to late Viséan intervals in the region. The oldest marine Mississippian (late Tournaisian) deposits are recorded in the south of the study region from the Loughrea/Tynagh area and further south in the Gort Borehole; they belong to the Limerick Province. They comprise the Lower Limestone Shale Group succeeded by the Ballysteen Group, Waulsortian Limestone and Kilbryan Limestone Formations. These rocks were deposited in increasing water depth associated with a transgression that moved northwards across Co. Galway. In the northwest and north of the region, marginal marine and non-marine Tournaisian rocks are developed, with a shoreline located NW of Galway City (Galway High). The central region of Co. Galway has a standard Viséan marine succession that can be directly correlated with the Carrick-on-Shannon succession in counties Leitrim and Roscommon to the northeast and east as far as the River Shannon. It is dominated by shallow-water limestones (Oakport, Ballymore and Croghan Limestone Formations) that formed the Galway-Roscommon Shelf. This facies is laterally equivalent to the Tubber Formation to the south which developed on the Clare-Galway Shelf. In the southeast, basinal facies of the Lucan Formation accumulated in the Athenry Basin throughout much of the Viséan. This basin formed during a phase of extensional tectonics in the early Viséan and was probably connected to the Tynagh Basin to the east. In the late Viséan, shallow-water limestones of the Burren Formation extend across much of the southern part of the region. They are characterized by the presence of rich concentrations of large brachiopod shells and colonial coral horizons which developed in predominantly high-energy conditions. These limestones also exhibit palaeokarstic surfaces and palaeosols which formed during regressive conditions of glacio-eustatically controlled cyclicity. Locally, slightly deeper water, lower energy conditions developed on the shelf with the formation of rare bryozoan-rich mud-mounds. Deep-water basinal facies were maintained in the central and southeastern parts of the region between the two shelves with the persistence of the Lucan Formation. Active syn-sedimentary faulting influenced deposition in the Viséan and interfingering of basinal sediments with slumps and shallow-water shelf carbonates are recognized.

S. R. Verkulich, M. V. Dorozhkina, Z. V. Pushina et al.

The interstadial marine deposits stratum was described in the Fildes Peninsula (King George Island) due to field and laboratory investigations during 2008–2011. The stratum fragments occur in the west and north-west parts of peninsula in following forms: sections of soft sediments, containing fossil shells, marine algae, bones of marine animals and rich marine diatom complexes in situ (11 sites); fragments of shells and bones on the surface (25 sites). According to the results of radiocarbon dating, these deposits were accumulated within the period 19–50 ky BP. Geographical and altitude settings of the sites, age characteristics, taxonomy of fossil flora and fauna, and good safety of the soft deposits stratum allow to make following conclusions: during interstadial, sea water covered significant part of King George Island up to the present altitude of 40 m a.s.l., and the King George Island glaciation had smaller size then; environmental conditions for the interstadial deposit stratum accumulation were at least not colder than today; probably, the King George island territory was covered entirely by ice masses of Last glacial maximum not earlier than 19 ky BP; during Last glacial maximum, King George Island was covered by thin, «cold», not mobile glaciers, which contribute to conservation of the soft marine interstadial deposits filled with fossil flora and fauna.

Jonathan Obrist-Farner, Wan Yang

Sedimentological and stratigraphic studies of seven stratigraphic sections of Permian Hongyanchi (HYC) and Quanzijie (QZJ) low-order cycles (LCs) in the Tarlong-Taodonggou half graben and Dalongkou area in Bogda Mountains, NW China, demonstrate effective approaches and methodology in cyclo- and time-stratigraphic analyses of complex fluvial-lacustrine deposits in an intracontinental rift setting. A new synchronous stratigraphic unit, the lower QZJ LC is defined. The lower and upper boundaries of this cycle include a regionally correlative disconformity, erosional unconformity, and conformity, across which significant and abrupt changes in palaeoenvironments and tectonic and climatic conditions occurred. The lower boundary is an erosional unconformity and disconformity with a high-relief topography that juxtaposes lacustrine deposits of the underlying HYC LC with the overlying meandering stream deposits of the lower QZJ LC, and was caused by a regional tectonic uplift. The upper boundary is a disconformity and local erosional unconformity and conformity, juxtaposing stacked paleosols developed on fluvial sediments with overlying fluvial and loessial deposits of the upper QZJ LC. The paleosols indicate landscape stability and a prolonged period of subaerial exposure and minimal deposition and suggest that climatic conditions were semi-arid with strong precipitation seasonality in the Tarlong-Taodonggou half graben and subhumid in the Dalongkou area. The fluvial-loessial deposits indicate a renewed tectonic uplift and a change in the atmospheric circulation pattern. The newly-defined lower QZJ LC facilitates accurate palaeogeographic reconstruction in the study area during a period of major tectonic and climatic changes. The interpreted tectonic and climatic conditions provide a critical data point in the mid-latitude east coast of NE Pangea during the Mid-Permian icehouse-hothouse transition. The results demonstrate that a process-response approach is effective in time-stratigraphic analysis of complex fluvial-lacustrine strata in a highly-partitioned rift basin.

DAWID ADAM IURINO

In mammals combined factors such as body size reduction and loss of peripheral teeth are often associated with endemism phenomena. This condition is particularly evident in insular contexts where is a complete geographic isolation. During the Pleistocene there have been several glacial stages, which changed the physiognomy of the Italian peninsula strongly influencing the distribution and morphology of mammalian faunas. Several genetic studies have shown that some Southern Italian areas have particular endemic species of small and medium size mammals. During Pleistocene these areas have been characterized by particular climatic/environmental conditions, and are generally called "glacial refugia". They represent geographically isolated areas over time, where the origin of faunas with peculiar features is favoured. In this study, the occurrence of Meles meles from the Late Pleistocene site of Ingarano (Apulia, Southern Italy) is documented for the first time. This taxon is represented only by a partial skull (splancnocranum) that, despite the relative completeness, includes peculiar and well-preserved dental features that could be related to a partial endemic condition. The fossil shows a reduced body size and the agenesis of peripheral teeth, both conditions that are typical of the extant badgers from Crete, Rhodes and Japan. To test this hypothesis, tomographic analysis have been provided to establish the dental agenesis, and, in order to understand the magnitude of the body size reduction, biometric analyses have been carried on. The obtained data have been compared to measures of the extant Eurasian badgers. SHORT NOTE

Pidek Irena Agnieszka

Early middle Pleistocene deposits from Łukow, correlated with the Cromerian complex, represent rare bi-partite Ferdynandovian pollen sequence encompassing two interglacial warmings (F1 and F2) separated by F1/2 cooling/glaciation and related to MIS 15-13. The paper presents pollen-based palaeoecological and palaeoclimate investigations in which plant climate indicators were applied. Additionally modern pollen dataset from the Roztocze region was used to evaluate vegetation history in terms of forest communities and presence and abundance of tree taxa sensitive to air temperature and humidity. Climate changes derived from pollen data indicate strong oceanic features of the climate of the first interglacial (F1) resembling those typical for the beginning of the Eemian, followed by cooling (F 1/2) with plant communities typical of the Pleistocene steppetundra, which undoubtedly indicate strong continentality, and subsequent return of more oceanic climate (F2) with mean remperature of the warmest month exceeding 18°C. Both pollen succession and climate changes recorded in the Łukow sediments correlate well with other bi-partite successions known from eastern part of European Lowlands.

GAIA CRIPPA

New data about the shell ultrastructure of species of the genus Glycymeris are obtained through a comparison between the fabric of recent specimens from Brittany (France) and fossil specimens collected from the Lower Pleistocene Castell’Arquato Formation cropping out along the Arda River in Western Emilia (Italy). This comparison, made using Scanning Electron Microscope (SEM), results in a strong similarity between the two fabrics, highlighting the good preservation of fossil ones. Both fossil and recent specimens show a well preserved outer simple crossed lamellar layer and an inner irregular and cone complex crossed lamellar layer. The inner and outer layers are separated by an irregular simple prismatic pallial myostracum. These mineralized layers are penetrated by parallel, not ramified and not bifurcated cylindrical tubules, which represent a peculiar character of the Arcoida shells. This analysis provides a more complete picture of Glycymeris shell ultrastructure. It shows that Glycymeris shell fabric has not changed for the last 2 million years and that the fossil specimens are pristine. Furthermore new data on the pattern and origin of tubules are reported, allowing to conclude that it is unlikely that they have a deterrence function for boring organisms. They may instead function to increase the volume of the organic content of the shell at lower metabolic cost without increasing the shell surface.

Bocharov Sergei G. , Maslovsky Andrey N.

Glazed ceramics of Byzantine origin, which came has been found on town sites of the Northern Black Sea region referring to the Golden Horde period (second half of the 13th – late 14th cc.), is characterized in the article. Materials from the urban centers of the Crimea (Solkhat, Sudak, Kaffa, Chersonese, Cembalo), the Azov Sea region (Azaq), and the lower reaches of the Don and Kuban rivers are discussed. The applied principles of ceramics classification have been formulated. On their basis, six major groups of Byzantine ceramic imports have been identified. For each group, a description of morphological and technological features, ornamentation methods and motifs has been provided; chronological framework of their arrival in the region has been specified. Conclusions have been offered as to the extent of distribution and the role played by diverse groups of Byzantine glazed ceramics in the cities of the Northern Black Sea region.