Neogene Research Articles

Molecular Phylogenetics and Estimation of Evolutionary Divergence and Biogeography of the Family Cordycipitaceae (Ascomycota, Hypocreales).

The Cordycipitaceae family of insecticidal fungi is widely distributed in nature, is the most complex in the order Hypocreales (Ascomycota), with members displaying a diversity of morphological characteristics and insect host ranges. Based on Bayesian evolutionary analysis of five genomic loci(the small subunit of ribosomal RNA (SSU) gene, the large subunit of ribosomal RNA (LSU) gene, the translation elongation factor 1-α (tef1-α) gene, the largest subunit of RNA polymerase II (rpb1), and the second largest subunit of RNA polymerase II (rpb2), we inferred the divergence times for members of the Cordycipitaceae, improving the internal phylogeny of this fungal family. Molecular clock analyses indicate that the ancestor of Akanthomyces sensu lato occurred in the Paleogene period (34.57 Mya, 95% HPD: 31.41-37.67 Mya), and that most species appeared in the Neogene period. The historical biogeography of Akanthomyces sensu lato was reconstructed using reconstructing ancestral state in phylogenies (RASP) analysis, indicating that it most likely originated in Asia. Combined morphological characterization and phylogenetic analyses were used to identify and taxonomically place five species within Cordycipitaceae. These include the following: (i) two new species, namely Akanthomyces baishanensis sp. nov. and Samsoniella sanmingense sp. nov., (ii) a new record species isolated from infected Lepidopteran host, Blackwellomyces lateris, (iii) a new record species in the genus Niveomyces, with sporothrix-like asexual morphs, namely N. multisynnematus, isolated from dipteran insects (flies), and (iv) a known species of the (hyper-) mycoparasite, Liangia sinensis, isolated from the fungus Ophiocordyceps globiceps (Ophiocordycipitaceae) growing on a dipteran host. Our data provide a significant addition to the diversity, ecology, and evolutionary aspects of the Cordycipitaceae.

Tracing Geological Stories: A Geotrail Study in Purwodadi Village, Tirtoyudo District, Malang Regency

Abstract Purwodadi Village of the Tirtoyudo District, Malang Regency was recognized as one of the 75 recipients of the Indonesian Tourism Village Award (ADWI) in 2023. To identify tourism potential in this area, it is an important to develop geology-based tourism, or geotourism. The study area is located in the Southern Mountain Zone, which mainly consists of the Old Andesite Formation (OAF), Paleogene to Neogene Period in ages. The OAF has a unique features and diverse composition of geological elements, as well as their geological history. However, they were undergone erosion, making them vulnerable to degradation. The diverse geological features of the region provide a unique chance to establish geotrails, which could become a significant attraction for geotourism. Therefore, the aim of this research is to characterize and assess geosites and geotrails in Purwodadi Village. The methodology were followed the Technical Standards for Geological Diversity Inventory and Geological Heritage Identification issued by the Geological Agency in 2017, along with a 4A tourism development analysis (Attraction, Accessibility, Amenities, Ancillary) to evaluate key aspects that influence the attractiveness and success of a geotourism destination. The results indicate that nine geosites have been identified with moderate to outstanding values, namely, Watu Kuning, Kedung Paimo, Lenggoksono Beach, Banyu Anjlok, Kletakan Cove, Bolu-Bolu Beach, Wedi Putih Beach, Wedi Awu Beach, and Lowo Cave. The main theme of geotrails in Purwodadi Village is Ancient Volcanic Traces of The Old Andesite Formation, with divided into three routes, northern route, western route, and eastern route. This finding provide valuable insights for the sustainable management of geotrails, focusing on the development of geotourism and the conservation of geological heritage in Purwodadi Village and its surroundings.

Biogeographical Origins of Caatinga Squamata Fauna

ABSTRACTAimSeveral lines of evidence have noted that open vegetation biomes in the Neotropics are younger than moist forests, leading us to question which historical processes shaped the current species distribution patterns in these new biome formations. Here we investigate the temporal patterns of speciation and colonisation from surrounding biomes (Amazonia, Atlantic Forest and Cerrado) in the Caatinga historical assembly of squamate species, to understand the role of geomorphological events and climate change in driving its diversification.LocationNeotropics.TaxonSquamata (snakes, lizards and amphisbaenians).MethodsWe used a phylogenetic tree and occurrence data for 459 squamate species distributed throughout four different biomes (Amazonia, Atlantic Forest, Cerrado and Caatinga) to reconstruct ancestral geographic ranges using the R package BioGeoBEARS. We used BAMM to estimate the rates of species diversification.ResultsOur results indicate that the current diversity patterns of squamates in the Caatinga were a result of pervasive faunal exchanges from adjacent biomes since the Paleogene, with similar numbers of dispersal events in each source area. The Neogene period was determinant in the diversification process, leading to the current assembly patterns of this group in the Caatinga.Main ConclusionsThe landscape transformation and climate change that increased aridity in northeastern Brazil probably shaped the diversification of dry‐adapted squamates in the Caatinga, like tropidurid lizards. However, the Pleistocene climatic fluctuations associated with the highly heterogeneous gradients of topography, geology, soils, climatic conditions, and different vegetation physiognomies could have facilitated faunal exchange with their neighbouring forested biomes, explaining the current presence of some typical forested lineages inside the Caatinga domain and help us to clarify the current distribution patterns of squamates in this region.

The role of the Andaman Nicobar fault (ANF) in shaping Narcondam offshore: Insights from high-resolution reflection seismic data

The study investigates the Andaman Nicobar Fault (ANF) and its role in the evolution of a volcano-supported basin adjacent to Narcondam Island, using three high-resolution 2D seismic reflection profiles. Migrated images show a fluid zone, determined through velocity and polarity analyses, with mean 1/Q values ranging from 0.0165 to 0.0096 for Lines 1 to 3. Additionally, polygonal faults are imaged, with varying thicknesses (0.1–0.4 km) of Miocene age, positioned above the fluid saturated zone. The migrated sections further show the branches of the ANF to be conduits for fluid migration and accumulation within the basinal deposits. The study finally highlights a shift in depocenter during the Neogene period, indicating fluctuations in sediment supply from the Irrawaddy River and the evolution of the ANF branch.

Comparison of the chloroplast genomics of nine endangered Habenaria species and phylogenetic analysis

BackgroundHabenaria, a genus in the family Orchidaceae, are the nearly cosmopolitan orchids, and most species have significant medicinal and ornamental values. Despite the morphological and molecular data that have been studied in recent years, the phylogenetic relationship is still unclear.ResultsWe sequenced, assembled, and annotated the chloroplast (cp) genomes of two species (Habenaria aitchisonii Rchb.f. and Habenaria tibetica Schltr.ex Limpricht) of Habenaria grown on the Qinghai-Tibetan Plateau (QTP), and compared them with seven previously published cp genomes which may aid in the genomic profiling of these species. The two genomes ranged from 155,259–155,269 bp in length and both included 132 genes, encoding 86 proteins, 38 tRNAs and 8 rRNAs. In the cp genomes, the tandem repeats (797), SSRs (2195) and diverse loci (3214) were identified. Comparative analyses of codon usage, amino frequency, microsatellite, oligo repeats and transition and transversion substitutions revealed similarities between the species. Moreover, we identified 16 highly polymorphic regions with a nucleotide diversity above 0.02, which may be suitable for robust authentic barcoding and inferring in the phylogeny of Habenaria species. Among the polymorphic regions, positive selection was significantly exerted on several genes, such as cemA, petA, and ycf1. This finding may suggest an important adaptation strategy for the two Habenaria species on the QTP. The phylogenetic relationship revealed that H. aitchisonii and H. tibetica were more closely related to each other than to the other species, and the other seven species were clustered in three groups. In addition, the estimated divergence time suggested that the two species separated from the others approximately 0.39 Mya in the Neogene period. Our findings also suggest that Habenaria can be divided into different sections.ConclusionsThe results of this study enriched the genomics resources of Habenaria, and SSR marker may aid in the conservation management of two endangered species.

Genome-wide species delimitation and quantification of the extent of introgression in eriophyoid mite Epitrimerus sabinae complex (Acariformes: Eriophyoidea)

Species complex hinders the exploration of terrestrial species diversity, particularly in small arthropod lineages that are morphologically indistinguishable from each other. The Epitrimerus sabinae complex in the Eriophyoidea provides a valuable case study in species complex delimitation, as they exhibit limited morphological variations. In this study, we obtained thousands of nuclear genomic single-nucleotide polymorphisms via whole-genome sequencing from 55 E. sabinae complex specimens, covering their potential all known distribution ranges. We implemented a framework to infer cryptic speciation, which involved phylogenetic and genetic clustering to identify potential species, followed by population demographic assessment to confirm lineage independence (and thus species status). Our results demonstrate that the E. sabinae complex comprises ten distinct species. These species range from highly divergent, genetically isolated lineages, to differentiated populations involving gene flow. This gene flow is widespread across species boundaries, indicating potential genetic introgression among them. Additionally, demographic analyses revealed that the ten species have followed unique trajectories in size change during the Quaternary period. Time-calibrated phylogenies further showed that speciation in the E. sabinae complex occurred rapidly, resulting in a rapid radiation during the Neogene period. Collectively, parallelism/convergence and recent divergence involving multiple gene flows may explain the homoplasy of E. sabinae complex. Our results highlight the integrated approach in species complex delimitation.

Chromosome-level genome of diamondback terrapin provides insight into the genetic basis of salinity adaptation.

Diamondback terrapins (Malaclemys terrapin centrata) exhibit strong environmental adaptability and live in both freshwater and saltwater. However, the genetic basis of this adaptability has not been the focus of research. In this study, we successfully constructed a ∼2.21-Gb chromosome-level genome assembly for M. t. centrata using high-coverage and high-depth genomic sequencing data generated on multiple platforms. The M. t. centrata genome contains 25 chromosomes and the scaffold N50 of ∼143.75 Mb, demonstrating high continuity and accuracy. In total, 53.82% of the genome assembly was composed of repetitive sequences, and 22435 protein-coding genes were predicted. Our phylogenetic analysis indicated that M. t. centrata was closely related to the red-eared slider turtle (Trachemys scripta elegans), with divergence approximately ∼23.6 million years ago (Mya) during the early Neogene period of the Cenozoic era. The population size of M. t. centrata decreased significantly over the past ∼14 Mya during the Cenozoic era. Comparative genomic analysis indicated that 36 gene families related to ion transport were expanded and several genes (AQP3, solute carrier subfamily, and potassium channel genes) underwent specific amino acid site mutations in the M. t. centrata genome. Changes to these ion transport-related genes may have contributed to the remarkable salinity adaptability of diamondback terrapin. The results of this study not only provide a high-quality reference genome for M. t. centrata but also elucidate the possible genetic basis for salinity adaptation in this species.

Gravity field and crustal structure of the Eastern Arm of Sulawesi and the Banggai Archipelago, Eastern Indonesia

The occurrence of extensive ophiolite masses and the development of the Batui-Balantak foreland thrust-fold belt on the Eastern Arm of Sulawesi can be attributed to the geologic process in the Neogene period when the Sulawesi Island Arc and the Banggai-Sula collided. Following the convergence, crustal fragments were further adjusted on a regional scale. This adjustment involved the rotation of crustal fragments into strike-slip faults on Sulawesi Island and the formation of extensional faults in the Banggai Archipelago. The analyses of the gravity field in the region of the eastern Sulawesi and Banggai Archipelago have yielded models that can potentially be interpreted as a representation of the underlying crustal structure in the region. The models can also be understood in a way that has consequences for tectonics. The tectonic episodes have played a significant role in the formation and development of sedimentary basins within the region. The primary objective of this study was to investigate the crustal structures of the Eastern Arm of Sulawesi and the Banggai Archipelago by means of analyzing gravity profiles. The findings of the analysis suggest that there is a slight thickening observed in the crustal block beneath the central portion of the eastern arm region. In addition, this area exhibits significant fracturing and severe attenuation. Furthermore, the crustal block has a dipped north-eastward trend in response to the ascent of the Molucca Sea oceanic crust.

High-resolution analysis of 3D fracture networks from Digital Outcrop Models, correlation to plate-tectonic events and calibration of subsurface models (Jurassic, Arabian Plate)

The performance of different reservoirs, both hydrocarbon and gas storage, is significantly influenced by the presence of natural fracture networks mainly originated in response to tectonic deformation. However, adequate characterization of fracture networks in the subsurface is often difficult since most of the used techniques are either spatially sparse (well and log data) or have limited resolution (seismic and well tests). In this study, we use UAV-based digital photogrammetry to reconstruct a 3D Digital Outcrop Model and characterize natural fracture sets of the late Jurassic Hanifa Formation (Tuwaiq Escarpment, Saudi Arabia). We analyzed the exposed fracture patterns in terms of fracture distribution, intensity, and lateral variability. The fracture dataset was collected using manual sampling approaches since the automatic sampling techniques are highly influenced by outcrop morphology thus not yet reliable to quantify and interpret fracture networks along reservoir outcrop analogues. The well-exposed late Jurassic outcrops in Wadi Birk, southern central Saudi Arabia, are considered analogous in depositional facies to subsurface reservoirs in the region. The observed fracture patterns are congruent with patterns reported from same-age formations in other parts of the Arabian Plate and hence can be related to plate-wide tectonic events that impacted Arabia during the Late Cretaceous (Alpine I) and the late Tertiary Period (Alpine II). This association provides support for using outcrop-based fracture studies as analogue scenarios for the orientation, distribution and intensity of fractures in subsurface reservoirs. The applied methodology for fracture network characterization have potential implications for hydrocarbon development, gas storage (H2) and Carbon Capture Utilization and Storage (CCUS).

Phylogenomic approaches reveal a robust time-scale phylogeny of the Terminal Fusarium Clade

The Terminal Fusarium Clade (TFC) is a group in the Nectriaceae family with agricultural and clinical relevance. In recent years, various phylogenies have been presented in the literature, showing disagreement in the topologies, but only a few studies have conducted analyses on the divergence time scale of the group. Therefore, the evolutionary history of this group is still being determined. This study aimed to understand the evolutionary history of the TFC from a phylogenomic perspective. To achieve this objective, we performed a phylogenomic analysis using the available genomes in GenBank and ran eight different pipelines. We presented a new robust topology of the TFC that differs at some nodes from previous studies. These new relationships allowed us to formulate new hypotheses about the evolutionary history of the TFC. We also inferred new divergence time estimates, which differ from those of previous studies due to topology discordances and taxon sampling. The results suggested an important diversification process in the Neogene period, likely associated with the diversification and predominance of terrestrial ecosystems by angiosperms. In conclusion, we presented a robust time-scale phylogeny that allowed us to formulate new hypotheses regarding the evolutionary history of the TFC.

Speciation patterns of Aedes mosquitoes in the Scutellaris Group: a mitochondrial perspective

The Scutellaris Group of Aedes comprises 47 mosquito species, including Aedes albopictus. While Ae. albopictus is widely distributed, the other species are mostly found in the Asia–Pacific region. Evolutionary history researches of Aedes species within the Scutellaris Group have mainly focused on Ae. albopictus, a species that raises significant public health concerns, neglecting the other species. In this study, we aimed to assess genetic diversity and estimate speciation times of several species within the Scutellaris Group. Mosquitoes were therefore collected from various Asia–Pacific countries. Their mitochondrial cytochrome c oxidase subunit 1 (cox1) and subunit 3 (cox3) sequences were analyzed alongside those of other Scutellaris Group species available in the GenBank database. To estimate the divergence time, we analyzed 1849 cox1 gene sequences from 21 species, using three species (Aedes aegypti, Aedes notoscriptus and Aedes vigilax) as outgroups. We found that most of the speciation dates occurred during the Paleogene and the Neogene periods. A separation between the Scutellaris Subgroup and the Albopictus Subgroup occurred approximately 64–61 million years ago (MYA). We also identified a split between species found in Asia/Micronesia and those collected in Melanesia/Polynesia approximately 36–35 MYA. Our findings suggest that the speciation of Aedes species within the Scutellaris Group may be driven by diversity in mammalian hosts, climate and environmental changes, and geological dynamics rather than human migration.

Tsunami Modeling Study in Geological Disaster Mitigation in the Kwandang Region

The northern coast of the northern arm of Sulawesi is the meeting place of 3 plates that collided with each other during the Neogene period. This condition makes the northern part of Gorontalo, especially Kwandang sub-district, very prone to earthquakes with magnitudes above 6 on the Richter scale (SR), which is one of the triggers for tsunamis. In the period from 1990 - 2008, there were 4 major earthquakes recorded in Gorontalo, namely 1990 (7.3 SR), 1991 (7.1 SR), 1997 (7.0 SR) and 2008 (7.7 SR). Therefore, further research is needed on the return period of the earthquake and the tsunami model that occurs and the sign of tsunami occurrence in the past. This research aims to determine the return period of the earthquake that caused the tsunami and the tsunami model as well as the sedimentology analysis of paleotsunami deposits. The calculation of the earthquake return period uses the Guttenberg-Richter method. Modeling calculations were carried out using the COMCOT numerical model. This model performs calculations by solving shallow water equations in the form of both linear and non-linear equations. Paleotsunami deposits were analyzed using the sedimentology method. The results of the calculation at a magnitude of 6.0 SR show that within 100 years, the study area has a chance of a potentially destructive earthquake of 1.14024978. The results of modeling the tsunami-prone zone, obtained an area of 165.598389 ha. And obtained paleotsunami deposits containing foraminifera with a sediment thickness of 14 cm.

Late Neogene and Quaternary Lacustrine History of the Great Salt Lake-Bonneville Basin

The Great Salt Lake-Bonneville basin has contained lakes for many millions of years and has been hydrographically closed for most of its history. Lakes in the lacustrine system have ranged from saline to fresh, and from shallow to deep. Tectonics, specifically crustal extension, which began roughly 20 million years ago as part of the formation of the Basin and Range Province, is the cause of lake-basin formation. Much of the rock record of lakes from Miocene time is faulted and has been eroded and/or buried. Pliocene and Quaternary lakes are better known. For much of the past ~5 Ma the basin has probably appeared similar to today, with a shallow saline terminal lake in a dry desert surrounded by mountains. Freshwater marshes and fluvial systems existed on the basin floor during part of the past ~5 Ma, probably were caused by the lack of inflow from the upper Bear River during the Neogene Period and most of the Pleistocene Epoch (that river was diverted into the basin during the Late Pleistocene), combined with a warm and dry climate. The largest deep-lake cycles were caused by changes to a cold and wet climate, which affected the water budget of the lake system and were correlated with periods of global glaciation. Based on limited data, the total length of time deep lakes existed in the basin is thought to be less than 10% of the past ~773 ka. Lake Bonneville, the most-recent of the deep-lake cycles, was probably the deepest and largest manifestation of the lake system in the history of the basin. Named deep-lake cycles during the past ~773 ka, are Lava Creek (~620 ka), Pokes Point (~430 ka), Little Valley (~150 ka), Cutler Dam (~60 ka), and Bonneville (~30 -13 ka). Of the Quaternary deep-lake cycles, only Lake Bonneville is represented by lacustrine landforms, outcrops, and cores of offshore deposits; no landforms from older deep-lake cycles exist (some may be buried under Lake Bonneville deposits but are not visible at the surface), and pre-Bonneville lakes are represented by sediments in limited outcrops and drill holes (including a set of cores taken by A.J. Eardley in the mid 20th century). During the past ~773 ka, deep-lake cycles were correlated with changes in the total volume of global glacial ice; the available evidence indicates that prior to ~773 ka deep-lake cycles were rare.

Quantitative biostratigraphy and paleoecology of Neogene tropical dinoflagellate cysts

Understanding the biostratigraphy of tropical areas during the Neogene period can be improved by studying dinoflagellate cyst events. These events have traditionally been identified through qualitative analysis. Nevertheless, to obtain consistent data on this subject, we used quantitative and probabilistic analysis of palynological data from the Southern Gulf of Mexico to identify dinoflagellate cyst events in the Neogene era. We analyzed a database of six wells, including 1,005 core and cuttings samples, a change from past qualitative analysis methods. With this quantitative approach with the RASC program, we obtained the Ranking Optimum Sequence (ROS) and compared it with ten published databases from Neogene tropical sites. The ROS identified eleven dinoflagellate species as age markers, we propose a most likely sequence of dinoflagellate cysts bioevents and define three assemblages: “Cantharellus” (Oligocene to early Miocene), “Hyalina” (Miocene), and “Patulum” (middle Miocene to Pleistocene), that can help recognize most Neogene stratigraphic stages in tropical areas. The comparison with the previous databases shows that the Gulf of Mexico and the tropical sites share 60% of the species, which enables age calibration of the optimal sequence and allows us to infer a possible provincial affinity. Additionally, we found a predominance of autotrophic dinocysts during the Neogene in tropical oceans. This trend mirrors the current abundance of gonyaulacoid cysts in tropical and subtropical areas, which has persisted since the Jurassic era.

Geologically calibrated mammalian tree and its correlation with global events, including the emergence of humans.

A robust timetree for Mammalia was constructed using the time calibration function of BEAST v1.10.4 and MEGA 11. The analysis involved the application of times of the most recent common ancestors, including a total of 19 mammalian fossil calibration ages following Benton etal. (Palaeontologia Electronica, 2015, 1-106) for their minimum ages. Additionally, fossil calibration ages for Gorilla, Pan, and a geologic event calibration age for otters were incorporated. Using these calibration ages, I constructed a geologically calibrated tree that estimates the age of the Homo and Pan splitting to be 5.69 Ma. The tree carries several significant implications. First, after the initial rifting at 120 Ma, the Atlantic Ocean expanded by over 500 km around Chron 34 (84 Ma), and vicariant speciation between Afrotheria (Africa) and Xenarthra (South America) appears to have commenced around 70 Ma. Additionally, ordinal level differentiations began immediately following the K-Pg boundary (66.0 Ma), supporting previous hypothesis that mammalian radiation rapidly filled ecological niches left vacant by non-avian dinosaurs. I constructed a diagram depicting the relationship between base substitution rate and age using an additional function in BEAST v1.10.4. The diagram reveals an exponential increase in the base substitution rate approaching recent times. This increased base substitution rate during the Neogene period may have contributed to the expansion of biodiversity, including the extensive adaptive radiation that led to the evolution of Homo sapiens. One significant driving factor behind this radiation could be attributed to the emergence and proliferation of C4 grasses since 20 Ma. These grasses have played a role in increasing carbon fixation, reducing atmospheric CO2 concentration, inducing global cooling, and initiating Quaternary glacial-interglacial cycles, thereby causing significant climatic changes.

An early diverging crocodylid from the Middle Miocene of Thailand highlights the role of SE Asia for the radiation of the Crocodyloidea

ABSTRACT The Neogene period witnessed the radiation of modern crocodylian genera, as evidenced from their fossil record in intertropical zones. Despite its recognition as a modern biodiversity hotspot, South East Asia remains undersampled for that age bin. Here, we describe a new crocodylian from northern Thailand, Antecrocodylus chiangmuanensis n. gen. n. sp. from the Middle Miocene lignite seams of Chiang Muan and refer to it other specimens from the nearby lignite seams of Mae Moh. The holotype specimen preserves the posterior half of the skull and mandible. Anatomical observations are aided by medical computed tomography. A phylogenetic analysis places the new taxon in a basal position relative to Crocodylidae. This discovery highlights the underrated fossil record of Neogene crocodyloids in Asia compared to Africa or Australia and allows us to reconsider palaeobiogeographic relationships between supposed endemic clades.

Analysis of the Genetic Model of the Extremely Narrow Channel Shallow Water Delta in DL-A Oilfield, Bohai Bay Basin.

In recent years, the oil and gas reserves discovered in shallow water deltas in China have continued to grow. The research on shallow water delta deposition models and depositional genesis is becoming more and more mature. In this latest discovery, a unique type of extremely narrow channel shallow water delta deposit was found at the top of the V oil group in the lower part of the Minghuazhen Formation during the Neogene period at DL-A Oilfield, located in the Bohai Bay Basin. The width of most single channels in this deposit measures between 100 and 200m, which is relatively rare and differs from existing research. To better understand this unique narrow channel shallow water delta deposit, a range of analysis methods were conducted including trace element analysis, major element analysis, grain size analysis, core observation, casting thin section observation, 3D seismic analysis, and other methods. These analyses were used to determine the sedimentary environment and sedimentary genesis of the deposit in the study area. The results show the following: (1) The top of the V oil group in the lower part of Minghuazhen Formation was deposited with a strong oxidizing environment. In the early stage, the climate was dry and cold, and gradually changed to warm and humid in the late stage. (2) Due to the frequent exposure to the surface, obvious weathered surfaces and sedimentary discontinuities were observed on the cores; the particle size analysis shows that the lamina types developed in the study area are clastic-clay laminae and clay-clastic laminae, which are mostly developed in shallow lakes area. (3) Observations of cores and thin sections also indicated that the hydrodynamic conditions frequently changed in the study area, alternating between strong and weak hydrodynamic conditions in a short period due to the alternating occurrence of flood and dry periods during the rainy season. Weak hydrodynamic conditions and slow water flow result in insufficient undercutting and sidecutting of rivers. The alternating occurrence of flood periods and dry periods has led to the development of crevasse splays and frequent river channel diversions, resulting in the inability of long-term stable development of the river channel. Besides, the change of water level has also led to the rebuilding of the river. Therefore, the multiple effects led to the formation of an extremely narrow channel shallow water delta. The accuracy of the sedimentary model is verified by a comparative study of the Shaliu River and Buha River in the modern Qinghai Lake. The new extremely narrow channels deposition model proposed this time further improves the deposition theory. At the same time, the modern depositional characteristics of the Shaliu River and Buha River also reveal the reservoir deposition between channels that cannot be distinguished by seismic data, providing guidance for the development of oil and gas in the study area.

Molecular evidence to support the transfer of Enteromorpha ovata to genus Ulva and evaluate its divergence using multi‐locus time‐calibrated phylogeny

Ulva has received considerable attention since its merger with tubular Enteromorpha (Linnaeus) Nees based on molecular evidence. Nevertheless, several nomenclatural and taxonomic proposals concerning tropical and subtropical species are still pending in want of investigations based on the altered circumscription and criteria of genetic diversity. Enteromorpha ovata Thivy et Visalakshmi ex H. Joshi et V. Krishnamurthy has a restricted geographical distribution only at Gopnath, India. In the present study, we for the first time provide a polyphasic approach to ascertain its taxonomic position, using morpho‐anatomy, ecology and molecular taxonomy with multigene markers (rbcL, tufA and ITS rDNA). Phylogenetic analysis based on rbcL, tufA and ITS rDNA gene sequences supported the recognition of this species within the genus Ulva. The recent revision by Kumar and Palanisamy proposed the new nomenclatural combinaton Ulva ovata (Thivy et Visalakshmi ex Joshi et Krishnamurthy) Aron Santhosh Kumar and Palanisamy, but they did not give molecular evidence while doing so, which we accomplished. Our time‐calibrated phylogeny suggested that U. ovata diverged from its respective sister lineages ~ 4.46 Mya in the Neogene period of the Cenozoic Era.

The fossil distribution of two pelagic lamniform sharks Alopias vulpinus and Lamna nasus, from South America

ABSTRACT The fossil record of the southeastern Pacific Ocean has been scarcely studied compared to other regions. We present the detailed description of two pelagic shark species, Alopias vulpinus (common thresher) and Lamna nasus (porbeagle) (Elasmobranchii: Lamniformes), from the Neogene of South America. The fossil teeth described here were recovered from the Bahia Inglesa Formation in Caldera, northern Chile. Our study provides the first comprehensive descriptions of fossil remains of A. vulpinus from Chile and L. nasus from the Americas. The occurrence of the common thresher shark represents the first published record and description of a representative from the family Alopiidae in northern Chile, whereas the fossil remains of the porbeagle shark are recorded for the first time in Chile. This study contributes to the understanding of the past distribution of shark species in the Eastern Pacific of South America during the Neogene period. It further confirms the particular abundance of lamniform sharks in the Neogene of Chile.

Petrogenesis of Adang and Talaya volcanic rocks, in the Mamuju area and its surrounding, West Sulawesi

The Adang Volcanic and Talaya Volcanic complex located in the Mamuju area are ancient volcanic complexes of the Neogene period. These two complexes consist of pyroclastic, volcaniclastic, and basic-intermediate lava containing the main modal minerals of leucite and clinopyroxene, making these rocks unique and rarely found in Indonesia. This study aims to determine the petrological and geochemical characteristics as well as the tectonic setting of rock formation. The rocks are generally porphyritic and vitrophyric in texture with various rock types as a result of magma differentiation. The Adang Volcanic Lava is composed of trachyandesite, tephriphonolite, trachyte, phonolite, and leucitite. Talaya Volcanic Lava is composed of basalt and trachybasalt rocks. Based on geochemical content, rocks have high alkalinity with wide range concentrations of K2O (0.27 – 10.12%), Na2O (0.54 – 11.06%), and total alkali (4.6 – 12.6%), as well as evidenced by the presence of feldspathoids. Rocks are divided into three groups, sodic, potassic, and ultrapotassic. The ultrapotassic rocks have similarities with Group III (Active Orogenic Zone) and Group I (Lamproite). The intensive enrichment of incompatible elements such as Rb and Th as well as the negative Nb and Ti anomalies reflect that magma derived from mantle metasomatism and is associated with subduction events. The genesis of the rock occurred in the tectonic setting of alkaline arc magmatism or continental extensional zone which was formed after the collision of the Banggai-Sula microcontinent with West Sulawesi. This process is also indirectly influenced by pre-collision subduction of the oceanic lithosphere.