Cretaceous Research Articles

A Comparative Geophysical Study of Major Basins in the Pranhita–Godavari Rift, India and Rio Grande Rift, USA

ABSTRACT In this study, we compare and contrast two major sub-basins in the Pranhita-Godavari rift in eastern India (Chintalapudi subbasin) and the Rio Grande rift in the western United States (Albuquerque basin) using bouguer gravity data analysis and integrated profile modeling constrained with seismic, drilling, and geological data. The Chintalapudi sub-basin formed during the break-up of Gondwana around 350 Ma, while the Albuquerque basin formed much later (30–35 Ma) in the interior of North America approximately synchronous with extension in the Basin and Range province. The Chintalapudi sub-basin is narrow and deep; and associated with a −60 mGal (low) gravity anomaly that is mostly due to Gondwana fluvial sediments of late Carboniferous (~350 Ma) to early Cretaceous age (~120 Ma). The negative gravity anomaly associated with the Albuquerque basin is −55 mGals (low) and the Cenozoic sediments were deposited on Mesozoic and Palaeozoic strata with Precambrian crystalline rocks being exposed along the basin flanks. This sub-basin is wide and shallow. Major faults which bound these basins were delineated by gravity modeling that integrated all of the available constraints, and the average depth to the basement at the basin centers calculated from gravity modeling is 4–5 km. However, for Chintalapudi sub-basin, if the residual gravity anamoly is considered, it may be reduced to about 3.5 km.

An Integrated Geological Model of Selective Carbonate Reservoir Wells, in Mishrif Formation in the Ratawi Oilfield, Southern Iraq

The majority of petroleum studies have traditionally focused on rocks that store hydrocarbons due to their economic significance, particularly in a period where oil is the primary global energy source. In the Cretaceous period, Iraq, and the Middle East, in general, are of particular interest due to the presence of formations that are significant for hydrocarbon storage and generation. The Mishrif Formation, dating to the Cenomanian-Early Turonian period, is a notable oil reservoir in southern Iraq. This formation’s distinctive features and extensive surface area make it a significant hydrocarbon repository, ranking second economically after the Zubair Formation in the region. This study analyzed six oil wells from the Mishrif Formation using various well logs (gamma ray, density, neutron, spontaneous potential, acoustic and resistivity) to extract petrophysical properties. The study identified rock types, layer boundaries, thicknesses, formation depths, and hydrocarbon-bearing zones. Through qualitative interpretation of these logs, the reservoir's characteristics were evaluated, including porosity, shale distribution, water and oil saturation. The results were visualized in three-dimensional models using the Petrel software, showing the distribution of these characteristics across the study wells. The Mishrif Formation is composed of four units (MA, CR-1, MB-1, and MB-2), with varying properties that were detailed in this study. Shale volume, averages between 0.04 % and 0.16%. Effective porosity ranges from 0.09% to 0.19%, indicating good reservoir quality; permeability ranges from 0.001 to 10 MD. Hydrocarbon saturation varies from 0.1to 0.7, while water saturation ranges from 0.3 to 0.9. The distribution of effective porosity in the Middle Mishrif reservoir unit is good throughout the field. In the Lower Mishrif reservoir unit, the effective porosity distribution is good in the central part of the field but poor in the northern and western parts. The formation thickness is homogeneous, indicating stable deposition. Hydrocarbon accumulations are present in both the Lower and Middle Mishrif reservoir units.

Tectono-sedimentologic and lithostratigraphic control in Aures Region: Case study Djebel Metlili, Batna, Algeria

This research delves into the geological features of the western section of the Aures Basin, with a primary focus on Djebel Metlili. The geological characteristics span Mesozoic and Tertiary deposits, ranging from the Triassic to the Quaternary epochs. Notably, the higher Cretaceous period stands out for its substantial carbonate-rich sequence. The research relied on geological maps, field observations, core samples, and laboratory analyses, including lithostratigraphic examinations (cross-section) and thin section. Structural features show that is formed by large regular folds of ENE-WSW or E-W direction. Anticlines and synclines are often affected by transverse accidents at the axes of the folds. In its northern part is located immediately south of the Belezma-Batna mountains. Structural analysis highlights significant tectonic disturbances, oriented in a northwest-southeast direction. A detailed lithostratigraphic examination reveals marly formations interspersed with limestone-rich layers containing Inoceramus. The southern part of Dj. Metlili, particularly the Santonian-Campanian series, unveils three distinct meso-transgressive sequences, linked to sea-level fluctuations associated with sedimentary basin subsidence. The studied area exhibits three distinct facies: one characterized by gray phosphate limestone with crisscrossed stratifications and agitated bioclastic sand, another featuring a mollusk-rich bioclastic limestone indicating a turbulent intertidal environment, and a third presenting a clay limestone bank with fine to medium grains and lumachels rich in oysters and gastropods. The associated grainstone texture in the microfacies suggests an internal platform environment marked by dissolution, bioturbation, and ferruginization. This comprehensive exploration provides valuable insights into the geological history of the region, significantly contributing to our understanding of its evolution over time.

Investigation of Geological Structures between Acıpınar-Hanobası-Altınkaya (Aksaray-Türkiye) About Satellite-Based Tectonic Lineaments

The region between Aksaray, Central Anatolia, and Altınkaya (Turkey) is included in the study area. The area's basement comprises ophiolites, igneous rocks from the Late Cretaceous period, and metamorphic rocks from the Palaeozoic to Mesozoic ages. Late Cretaceous-Quaternary sedimentary units were formed in the area called Tuzgolü Basin. The Late Cretaceous-Mio-Pliocene sedimentary rocks in the study area have undergone polyphase deformation under compressive and extensional tectonic regimes. As a result of these deformations, the rocks in the area have developed folded, faulted and fractured structures. These structures have formed lineations. In this study, the relationship between the tectonic lineaments identified in the field and those obtained by computer processing of Landsat 8 images was evaluated. It was found that the lineaments belonging to the Tuzgölü fault and the structural geological structures determined in the field are in significant agreement.

Detrital zircon provenance links between outcrop and subsurface, Rocas Verdes and Magallanes-Austral Basins, Patagonia

Analyzing how provenance signatures of tectonically complex ancient sedimentary basins vary between the outcrop and the subsurface provides a more complete sediment provenance history. The 500+-km-long outcrop belt of the Rocas Verdes and the Magallanes-Austral Basins in southern Patagonia and its subsurface to the east allow us to constrain relationships between longitudinal and transverse sediment sources feeding the basin. New detrital zircon U-Pb ages (n = 2558) from nine subsurface core samples from the Springhill, Piedra Clavada, and La Anita Formations along a 140 km E-W seismic reflection transect (50°S, 71.5°W–69.5°W) reveal the provenance of the basin’s eastern subsurface extent and the influence that tectonic activity can have on sediment capture. Detrital zircon ages (n = 1068) were also collected from four outcrop Springhill Formation samples 140 km NW from the transect near Lago San Martín. Maximum depositional ages (MDAs) from the Springhill Formation cores range from 159 to 157 Ma, which are older than correlative outcrop ages of 151–148 Ma. MDAs from the Piedra Clavada and La Anita Formations range from 93.7 to 91.5 Ma and from 79.3 to 78.3 Ma, respectively, and overlap in age or are slightly younger than outcrop ages. The unimodal Late Jurassic age distribution from the Springhill Formation suggests that it almost exclusively was sourced by recycling of the underlying El Quemado Complex. Early–Middle Jurassic ages in the Early Cretaceous Piedra Clavada Formation samples suggest the basin was either sourcing from the North Patagonian Massif to the N-NE and from the Deseado Massif to the NE or recycling exhumed volcaniclastic sequences in the northern margin of the basin. By the Late Cretaceous, the basin fill was more locally sourced, as suggested by the muted abundance of Early–Middle Jurassic ages in La Anita Formation samples and a second mode of Late Jurassic–Early Cretaceous ages locally derived from recycling of the exhumed El Quemado Complex from the Patagonian fold-and-thrust belt. We suggest that the latitudinal and local transverse drainages that sourced the Magallanes-Austral Basin outcrop belt also fed the eastern, subsurface extent of the basin. Results of this work highlight the importance of using several types of provenance methods and a three-dimensional approach to study the erosional history of sedimentary basins.

Paleolatitudinal movements of the eastern Sakarya Zone from Jurassic to Eocene

The study area covers a region oriented north-south from the Black Sea coastline in the north to the Kelkit Basin in the south within the eastern Sakarya Zone in northern Türkiye. The objective of this study is to investigate the paleolatitudinal movements of the eastern Sakarya Zone during the Jurassic-Eocene time interval through paleomagnetism. Various volcanic and sedimentary units (e.g., the Şenköy, Berdiga, Mescitli, Çatak, Kızılkaya, and Çağlayan Formations) spanning the time interval from the Early Jurassic to Middle Eocene were identified. A total of 98 locations belonging to Early/Middle Jurassic to Eocene volcanic and sedimentary units were selected for paleomagnetic core sample collection. The samples were subjected to demagnetization through thermal and alternating field methods. Characteristic remanent magnetization directions (ChRM) were obtained. Isothermal remanent magnetization (IRM) and high temperature susceptibility (HTS) measurements were made to identify the minerals responsible for magnetization. To ascertain whether magnetization was acquired through rock formation or as a consequence of subsequent tectonic processes, conglomerate and fold tests were performed. The results showed that magnetization was acquired before folding, i.e., the rocks have primary magnetization. Polarity tests were also conducted using coeval normal and reverse polarity sites. The results indicate that the mean magnetization direction for the Early-Middle Jurassic is 18.1°/55.2° (D/I) and 3.3°/51.5° (D/I) for sedimentary and volcanic rocks, respectively, and 348.7°/46.7° (D/I) for Late Jurassic/Early Cretaceous sedimentary rocks. In the Late Cretaceous period, the mean magnetization direction is 8.0°/49.3° (D/I) and 9.1°/47.0° (D/I) for sedimentary and volcanic rocks, respectively. In the case of the Early/Middle Eocene, the mean magnetization direction is 348.6°/52.7° (D/I) and 5.9°/48.8° (D/I) for sedimentary and volcanic rocks, respectively. In this study, the E/I correction was applied to the Late Jurassic/Early Cretaceous sedimentary rocks, and paleolatitude data obtained from sedimentary rocks were also utilized. Our paleomagnetic results indicate that the eastern Sakarya Zone was situated at latitudes spanning from 27.9° to 35.7° during the Early Jurassic - Middle Eocene time interval. In consequence, the eastern Sakarya Zone constituted a portion of the southern margin of the Eurasian continent during the Late Jurassic and Middle Eocene periods.

A new palynological assemblage of the Nantun Formation in the Huhehu Sag, Hailar Basin, NE China: Implications for paleoenvironments

The Cretaceous period, recognized as one of the warmest in Earth's geological timeline, is crucial for understanding paleoclimatic conditions. Palynological analyses, focusing on spores and pollen, play a vital role in reconstructing paleoenvironmental. This study emphasizes the relationship between climate and plant distribution through detailed palynological analyses. It reports the first discovery of abundant and diverse palynomorphs from the lower Nantun Fm in the Hailar Basin, Inner Mongolia, China. The identified palynological assemblage, termed the Protoconiferus flavus—Pinuspollenites sp.—Quantouendinium sp. (PPQ) assemblage, provides significant insights into the Early Cretaceous flora of northeastern China. The PPQ assemblage can be chronologically attributed to the Hauterivian–early Barremian interval, consistent with the LA–ICP–MS zircon U–Pb isotope ages of the Nantun Fm volcanic rocks. Paleovegetation reconstruction reveals a prevailing dominance of coniferous vegetation in the region represented by the PPQ assemblage, indicative of a characteristic of mid-to high-latitude mountain coniferous forest landscape. The climatic was mainly humid or semi-humid. This conclusion is supported by the abundance of freshwater dinocyst and green algae fossils, suggesting that sedimentation occurred in a shallow, freshwater hydrostatic environment with an estimated water temperature of approximately 20–25 °C. The environment was also nutrient-rich, which facilitated the proliferation of green algae such as Scenedesmus, Pediastrum, and Tetraedron. Identifying this assemblage is important for determining the age of the lower Nantun Fm, reconstructing paleovegetation and paleoclimate, and analyzing the lacustrine water conditions during the sedimentary period in the Hailar Basin.

Using PySpark to accelerate batch data point rotation for paleogeographic reconstruction

ABSTRACT Batch paleogeographic point rotation (BPPR) is a PySpark-based extensible batch data point rotation method that accelerates rotation during paleogeographic reconstruction. Data point rotation is an important part of paleogeographic reconstruction and a significant tool for exploring the co-evolution of Earth and life. However, current point rotation techniques have challenges with processing speeds when handling extensive paleogeographic data. Therefore, this study introduced a parallel-computing framework to construct a BPPR. This method combines PySpark and PyGPlates, which can partition points and compute them simultaneously in multiple threads. The rotation of 232,277 fossil occurrences from the Cretaceous Period in the Paleobiology Database (PBDB) was completed within 26 s. By contrast, an alternative GPlates method completed the same task within 96 s. The proposed method supports CSV, EXCEL, SHP, and other data formats, thereby avoiding possible software switching requirements when using methods associated with GPlates. Using synthetic and real paleontological data as experimental datasets, BPPR proved to be nine times more efficient than GPlates when rotating 900,000 points. This efficiency improvement significantly enhanced data-driven paleogeographic analysis. The parallel strategy employed can be broadly applied to massive data analysis in geoscience.

Emplacement and landscape controls on ancient submarine volcanism: 3D seismic geomorphological analysis of Cretaceous volcanic activity in the Browse Basin, Australian North West Shelf

Ancient submarine volcanic systems preserved within sedimentary basins provide opportunities to investigate the time and spatial distributions of intrusive and extrusive rocks, though existing work has largely focused on the geometrical features of submarine volcanic products, with limited interrogation of their interactions with sedimentary processes. This study investigates a buried submarine volcanic system within the Browse Basin, Australian North West Shelf. Through the integration of three-dimensional seismic reflection survey with borehole data, our study reveals intricate geometric features of a submarine volcano and lava channels, and their relationship to an associated intrusive network of Early Cretaceous age that has been preserved beneath ∼3.5 km of sedimentary overburden. In planform, the volcano has a diameter >4.5 km with a preserved height reaching 650 m. Meandering lava flow channels extend ∼20 km southward of the volcanic edifice, forming lava lobes with pressure ridges at the flow termini. Abundant sheet intrusions, identified within underlying Jurassic and older strata, indicate a magma transport from the north. The localised accumulation of sills led to variations in paleo-seafloor topography, influencing the direction of lava flows and post-volcanic sedimentation patterns. Our findings have a broad range of implications encompassing submarine volcanism and their impacts on basin dynamics.

Relationship between stratigraphic overlap and sedimentary facies evolution of the Junggar Basin, Northwest China

The interaction between the topography of the slope zone on the edge of the basin and the distribution of sediments is crucial for accurately predicting sediment distribution, but few studies emphasize the impact of stratigraphic overlap on the spatial evolution of sedimentary facies. The tectonic movement and sedimentary environment of Hala’alat Mountain in the northwest margin of the Junggar Basin are complex, and the sedimentary model of the whole Cretaceous system is still unclear. This article uses lithology, logging, and seismic data to explain the evolution process and sedimentary model of the Cretaceous system. The significant overlap of Cretaceous strata in the research area has a significant impact on the distribution of sedimentary facies zones and the development of sedimentary systems. Furthermore, this article explores the genesis mechanism of the Cretaceous stratigraphic overlap phenomenon, clearly defines the boundary range of stratigraphic overlap, and deeply analyzes how sedimentary facies zones are distributed and their subsequent evolution trends after the formation of overlap. The results demonstrate that there are apparent stratigraphic overlap phenomena in the second member (K1q2) and the third member (K1q3) of the Cretaceous Qingshuihe Formation in this area. The lithology at the bottom of the formation is grey sand conglomerate with finer grain size in the upper part, and the sedimentary facies are transitioned from fan delta facies to shore shallow lake beach bar facies. In member 1 (K1h1), member 2 (K1h2) and member 3 (K1h3) of the Hutubi Formation, due to the gradual slope and relatively stable sedimentary environment, the distance of stratigraphic overlap becomes shorter, the stratigraphic overlap phenomenon is no longer apparent and the sedimentary facies zone does not change. The study not only reveals the intrinsic relationship between stratigraphic overlap and the distribution of sedimentary facies zones, but also deepens the understanding of the dynamic evolution laws of sedimentary systems. The study on the overlap sedimentary mechanism of the Hala’alat Mountain in the northwest margin of Junggar Basin has reference significance.

The Cretaceous World (GSL SP544)

The Cretaceous System was first established by Jean Baptiste Julien d'Omalius d'Halloy based on his geological mapping of France and the adjacent areas of the Low Countries and Northern Italy. His map, which was published in 1822, has a legend with a rock unit identified as ‘ Terrain Crétacé ’ and that was the birth of the Cretaceous System that we still use today. Unlike many of the other geological systems, there was no definitive publication. The Cretaceous, as currently defined, occupies the interval of time from 145 Ma to 66 Ma, making it one of the longest in the Phanerozoic. The Cretaceous includes both icehouse and greenhouse (even hothouse) conditions and much of the time is characterised by exceptionally high sea levels.

Introduction to the Cretaceous System: Regional Studies (SP 545)

The Cretaceous System was first established by Jean Baptiste Julien d'Omalius d'Halloy based on his geological mapping of France and the adjacent areas of the Low Countries and Northern Italy. His map, which was published in 1822, has a legend with a rock unit identified as ‘ Terrain Crétacé ’ and that was the birth of the Cretaceous System that we still use today. Unlike many of the other geological systems, there was no definitive publication, only an account about the generation of the map. The Cretaceous, as currently defined, occupies the interval of time from 145 Ma to 66 Ma, making it one of the longest in the Phanerozoic. The Cretaceous includes both icehouse and greenhouse (even hothouse) conditions and much of the time is characterised by exceptionally high sea levels. These have provided us with widespread deposits of Cretaceous age, from the Arctic to the Antarctic, and all latitudes between. The range of sediments, both marine and terrestrial, is also a backdrop to a range of faunas and floras, some of which are widespread while others are endemic as a result of the Cretaceous dispersion of the continents.

Cretaceous stratigraphy in the Songliao Basin, NE China

The Songliao Basin is one of the largest non-marine oil- and gas-bearing basins that developed during the Cretaceous period, recording an almost complete Cretaceous stratigraphy. With oil and gas exploration, as well as the Continental Scientific Drilling Project of Cretaceous Songliao Basin (CCSD-SK) (2006–21), significant progress has been made on the stratigraphy of the Songliao Basin. The Songliao Basin is therefore important for understanding the non-marine Cretaceous system. Based on lithostratigraphy, sequence stratigraphy, biostratigraphy, geochronology, magnetostratigraphy and cyclostratigraphy, a comprehensive stratigraphical framework of the Songliao Basin has been established in this study. The Lower Cretaceous strata (Hauterivian–Albian) of the basin are dominated by volcanic–sedimentary deposits, while the lower-middle Upper Cretaceous (Cenomanian mid-Campanian) strata are dominated by lacustrine deposits. The upper Upper Cretaceous strata (late Campanian–Maastrichtian) are dominated by fluvial–lacustrine deposits. Fossils are very abundant in the Songliao Basin, and three biotas – the Jehol Biota sensu lato , the Songhuajiang Biota and the Mingshui Biota – are recognized in the Songliao Basin. Furthermore, several important geological events, such as lake anoxic events, seawater incursion events and the K/Pg boundary extinction events are all recorded in the Songliao Basin.

Phylogenetic and divergence analysis of Pentatomidae, with a comparison of the mitochondrial genomes of two related species (Hemiptera, Pentatomidae).

Pentatomidae, the most diverse family of Pentatomoidea, is found worldwide. Currently, the phylogenetic relationships among Pentatomidae tribes remain unstable, and subfamily divergence has not been estimated. Here, we sequenced and analyzed the complete mitochondrial genomes of two species of Lelia, and studied the phylogenetic relationships among Pentatominae tribes. We also selected three available fossil as the calibration points in the family, and preliminarily discussed the divergence time of Pentatomidae. Trees of Pentatomidae were reconstructed using the Bayesian inference method. Divergence times of Pentatominae were estimated based on the nucleotide sequences of protein-coding genes with a relaxed clock log-normal model in BEASTv.1.8.2. The results showed that the gene arrangements, nucleotide composition, and codon preferences were highly conserved in Lelia. Further, a phylogenetic analysis recovered Eysarcorini, Strachiini, Phyllocephalini, and Menidini as monophyletic with strong support, however, the monophyly of Antestiini, Nezarini, Carpocorini, Pentatomini and Cappaeini were rejected. Moreover, Pentatominae diverged from Pentatomidae soon after the origin of the Cretaceous Period, at approximately 110.38 Ma. This study enriches the mitochondrial genome database of Pentatomidae and provides a reference for further phylogenetic studies, and provides a more accurate estimate of divergence time.

Cicada nymph trace fossils from South American Maastrichtian paleosols

The Cretaceous was a pivotal Period in the evolution of major insect groups, including cicadas. Insect diversification led to an increased complexity in the paleosol ichnofabrics due to the emergence of chambers associated with reproductive and feeding behaviors. Therefore, any new record of trace fossils attributed to cicadas from the Cretaceous period represent a significant advancement in understanding the diversification of this group and the emergence of insect feeding chambers, throughout the geological record. This work describes the record of the ichnogenus Feoichnus attributed to feeding chambers of cicada nymphs (Hemiptera: Cicadidae) from Maastrichtian paleosols developed in floodplain deposits of The Marília Formation (Bauru Basin, Brazil). The described Feoichnus chambers are elongated, hemispherical, and upwardly concave, with a lining covering the inner surface of the wall. The inner surface exhibits thin, irregular ridges and grooves, likely associated with fine roots. Feoichnus occurs in association with Beaconites antarcticus and root traces found within the feeding chamber, it could be indicating the movement of the trace maker and the feeding chamber from one root to another. These characteristics indicate the xylem-feeding behavior of Feoichnus trace maker in accordance with extant cicada nymph ecology. The presence of Beaconites antarcticus associated with Feoichnus and rhizoliths probably represents the foraging behavior of cicada nymphs and the displacement of feeding chambers in well-drained, rooted soils. Therefore, the cicada nymph could be the trace maker of both traces representing feeding and locomotion behavior. This contribution expands the knowledge about plant–insect interactions and insect groups that compose the Cretaceous paleosols ichnofabrics from South America.

The First Report of Late Valanginian–Early Aptian (Early Cretaceous) Ammonites and Chemostratigraphy of Eastern Anatolian, Olur‐Erzurum, Türkiye

ABSTRACTThis study is based on stable isotope analysis of a rich ammonite assemblage from the Sogukcam Formation, which is widely exposed in Yesilbaglar (Olur‐Erzurum, NE Türkiye). The presence of ammonid, planktic, and benthic foraminifers in the marine sediments suggests that they are from the early Cretaceous period. The late Valanginian‐early Aptian‐rich ammonite assemblage includes the following genera and species: Acrioceras sp., Barremites difficilis, Barremites sp., Crioceratites duvalii, Crioceratites sp., Deshayesites aff. dechyi, Deshayesites sp.1, Deshayesites sp.2, Deshayesites sp.3, Deshayesites sp., Dufrenoyia cf. dufrenoyi, Dufrenoyia cf. furcata, Dufrenoyia sp., Hemihoplites sp., Heteroceras sp., Neocomites sp., Phyllopachyceras infundibulum, Protetragonites cf. quadrisulcatus, Protetragonites sp., Ptychoceras sp., Turkmeniceras cf. geokerense, and Turkmeniceras sp. This assemblage suggests that the Sogukcam Formation's deeper facies formed in the late Valanginian to early Aptian period. Fossils and δ18O data show normal paleosalinity levels. During the late Valanginian‐early Aptian period, δ18O values ranged from −3.67‰ to −2.24‰, with paleotemperatures ranging from 21.3°C to 27.9°C. δ13C positive values range from +0.65‰ to +2.86‰. δ13C isotope data show the oxygen minimum zone (OMZ) and changes in sea level and productivity. The presence of planktonic foraminifera and the ammonite assemblage indicates that the formation was deposited in warm subtropical waters ranging from the outer shelf to the open sea.

Comparative Mitogenomics Analysis Revealed Evolutionary Divergence among Purpureocillium Species and Gene Arrangement and Intron Dynamics of Ophiocordycipitaceae.

The species of Purpureocillium are cosmopolitan and multitrophic fungi that can infect a wide range of invertebrate hosts. This study reports the mitogenome of P. atypicola, a specialized spider pathogenic fungus. The 112,465 bp mitogenome encoded genes typically found in fungal mitogenomes, and a total of 52 introns inserted into seven genes. A comparison with three other Purpureocillium species revealed significant differences in length and intron number, primarily due to intron variation; however, there was no dynamic variation in the introns of the cox1 gene within the same species of the Purpureocillium genus. Different mitochondrial protein-coding genes showed variable degrees of genetic differentiation among these species, but they were all under purifying selection. Additionally, frequent intron loss or gain events were detected to have occurred during the evolution of the Ophiocordycipitaceae mitogenomes, yet the gene arrangement remains conserved. A phylogenetic analysis of the combined mitochondrial gene set gave identical and well-supported tree topologies. The estimated age of the crown of Ophiocordycipitaceae and Purpureocillium were around the Early Cretaceous period (127 Mya) and Late Cretaceous period (83 Mya), respectively. The results of this study advance our understanding of the genomics, evolution, and taxonomy of this important fungal group.

The evolution of ectomycorrhizal symbiosis and host-plant switches are the main drivers for diversification of Amanitaceae (Agaricales, Basidiomycota)

BackgroundEvolutionary radiation is widely recognized as a mode of species diversification, but the drivers of the rapid diversification of fungi remain largely unknown. Here, we used Amanitaceae, one of the most diverse families of macro-fungi, to investigate the mechanism underlying its diversification.ResultsThe ancestral state of the nutritional modes was assessed based on phylogenies obtained from fragments of 36 single-copy genes and stable isotope analyses of carbon and nitrogen. Moreover, a number of time-, trait-, and paleotemperature-dependent models were employed to investigate if the acquisition of ectomycorrhizal (ECM) symbiosis and climate changes promoted the diversification of Amanitaceae. The results indicate that the evolution of ECM symbiosis has a single evolutionary origin in Amanitaceae. The earliest increase in diversification coincided with the acquisition of the ECM symbiosis with angiosperms in the middle Cretaceous. The recent explosive diversification was primarily triggered by the host-plant switches from angiosperms to the mixed forests dominated by Fagaceae, Salicaceae, and Pinaceae or to Pinaceae.ConclusionsOur study provides a good example of integrating phylogeny, nutritional mode evolution, and ecological analyses for deciphering the mechanisms underlying fungal evolutionary diversification. This study also provides new insights into how the transition to ECM symbiosis has driven the diversification of fungi.

A new carcharodontosaurid specimen sheds light on the anatomy of South American giant predatory dinosaurs.

Carcharodontosaurids were gigantic terrestrial dinosaurs and top predators of dinosaur faunas in Gondwanan landmasses during the "Mid"-Cretaceous Period. Despite their wide geographical and stratigraphical distribution, essential parts of their anatomy are still poorly known. The present contribution aims to describe a new partial skeleton of the carcharodontosaurid Taurovenator violantei, which was previously known only by an isolated postorbital bone coming from Cenomanian-Turonian beds of northern Patagonia, Argentina. The neck of Taurovenator is composed of notably high anterior cervicals, bearing neural spines with expanded, flange-like dorsal tips which are successively imbricated. This condition has been reported previously in the carcharodontosaurid Acrocanthosaurus, but its occurrence in Taurovenator and other members of the clade suggests it may represent a synapomorphy of this theropod family. This unique neck morphology was probably related to strong modifications in musculature and restriction in the range of movements within the neck, but not with the head. The new specimen also affords valuable anatomical information on the forelimb of Patagonian carcharodontosaurids. As in other giganotosaurines, Taurovenator shows strongly reduced forelimbs, particularly the forearm, showing hand elements with elongated non-ungual phalanges, and well-marked articular surfaces and muscular insertions, suggesting highly movable digits. This new specimen of Taurovenator allows us to expand anatomical and morpho-functional discussions about the carcharodontosaurid clade.

Vertebrate paleoburrow as a seasonality indicator in early Cretaceous Três Barras formation (Brazil)

Vertebrate burrows serve as windows into the past, revealing the activities of various organisms and providing clues about their paleoenvironmental conditions. This study focuses on a vertebrate paleoburrow from the Três Barras Formation, Minas Gerais state, southeastern Brazil, aiming to detail and reconstruct aspects of the paleoclimatic conditions that acted in this area during the early Cretaceous within a predominantly eolian paleoenvironment. Through detailed analysis of the sedimentary facies and morphological examination of the burrow, this study suggests that the structure was likely produced by lungfish or lizards. It is located within proximal crevasse splay deposits interbedded with fine floodplain sediments, indicating periods of flooding in a meandering fluvial setting that developed in the marginal areas of the eolian system of the Três Barras Formation. Comparison with other paleoburrows from neighboring basins further enhances our understanding of the paleoenvironmental conditions during the early Cretaceous Period. These findings reinforce evidence of seasonality and suggest a period of intense humidity during the deposition of the Três Barras Formation, which had previously been interpreted as exclusively aeolian.