Rock Magnetism of Late Cretaceous to Middle Eocene Strata in the Lesser Himalaya, Western Nepal: Inferences Regarding the Paleoenvironment

The growth of the southern piedmont of the Himalayan boundary and its depositional setting has changed since uplift of the Himalaya due to continental Indian-Eurasian collision, which has resulted in variation in magnetic minerals in marine- and terrestrial-facies sediments. In this paper, we utilize rock magnetism data from the late Cretaceous to middle Eocene strata, including the Amile and Bhainskati formations from the Lesser Himalaya (western Nepal), to understand the mechanism controlling magnetic susceptibility (χ). The active tectonics strongly influenced saturation isothermal remanent magnetization (SIRM), HIRM, and hysteresis loops, forming both low-coercivity minerals in sediments with low χ from the terrestrial facies (zones I, IIIA, and V) and high-coercivity minerals in the sediments with high χ from the marine facies (zones II, IIIB and IV). Thermomagnetic κ-T curves and frequency-dependent χ (χfd%) values show that sediments with low χ and high χ carry magnetite with coarse non-superparamagnetic (SP) grains and hematite with SP grains, respectively. Comparing the χ data with the lithologic, sedimentary environments, geomorphic features, and sea level data, we propose that low χ values were mainly produced by an increase in terrigenous detrital influx during the regression period of the Tethys Sea, while high χ values formed in marine sediments, which prompted the appearance of ferromagnetic-antiferromagnetic and paramagnetic minerals during the transgression of the Tethys Sea.

Phylogenomics illuminates the evolution of bobtail and bottletail squid (order Sepiolida)

Bobtail and bottletail squid are small cephalopods with striking anti-predatory defensive mechanisms, bioluminescence, and complex morphology; that inhabit nektobenthic and pelagic environments around the world’s oceans. Yet, the evolution and diversification of these animals remain unclear. Here, we used shallow genome sequencing of thirty-two bobtail and bottletail squids to estimate their evolutionary relationships and divergence time. Our phylogenetic analyses show that each of Sepiadariidae, Sepiolidae, and the three subfamilies of the Sepiolidae are monophyletic. We found that the ancestor of the Sepiolinae very likely possessed a bilobed light organ with bacteriogenic luminescence. Sepiolinae forms a sister group to Rossinae and Heteroteuthinae, and split into Indo-Pacific and Atlantic-Mediterranean lineages. The origin of these lineages coincides with the end of the Tethys Sea and the separation of these regions during the Eocene and the beginning of the Oligocene. We demonstrated that sepiolids radiated after the Late Cretaceous and that major biogeographic events might have shaped their distribution and speciation.

Geometry and the Mechanism of Landslide Occurrence in a Limestone Area – Case Examples of Landslides in Vietnam and from Europe, China, and Japan –

Landslide damage has been reported in many limestone areas in Europe, where the population lives close to limestone areas, and in Guilin in southern China and Ha Long in Vietnam, which are known for their unique limestone landscapes. There are few studies on the mechanism and type of landslide motion in and around such limestone areas. The lack of basic data is a problem for risk assessment and countermeasures in limestone areas. In this study, we summarized the causes and mechanisms of landslide occurrence, including geology and groundwater, focusing on six landslides that occurred in limestone areas in northern Vietnam, and classified them into six types of landslide movement. In the case of Japan, the occurrence of landslides in limestone areas is rare despite the wide distribution of limestone, and it is difficult to classify the type of movement. Differences in the landslide mechanisms are caused by the difference between limestones generated in the pelagic environment of Japan and limestones developed along the Tethys Sea coast, which are mixed with pelitic rocks as shallow-water sediments in Europe, China, and Vietnam. It is necessary to elucidate the relationship between landslides and the formation environment and sedimentary characteristics of limestone as an accretionary prism based on comparisons of a wide range of cases in future studies.

Confusing Invader: Acanthocyclops americanus (Copepoda: Cyclopoida) and Its Biological, Anthropogenic and Climate-Dependent Mechanisms of Rapid Distribution in Eurasia

Acanthocyclops americanus (Marsh, 1892), first described in Wisconsin (USA), was discovered shortly thereafter in Great Britain and then widely distributed in the Palearctic. Its current range includes Europe, North Africa, western and central Siberia with the largest number of findings along the migration tracks of aquatic birds. Until recently, the northern border was the 60th parallel, but in the last decade it has expanded further into the Arctic. The most rapid expansion of its range in Europe happened in the middle of the last century, which was partially hidden from scientists due to a taxonomic mistake caused by the merging of its name with the native Palearctic form Acanthocyclops robustus (Sars, 1863). This problem was solved only recently with the help of molecular genetic tools, allowing a return to the study of biological, anthropogenic and possible climate-dependent mechanisms of the successful rapid invasion of A. americanus into the Palearctic. This paper, along with a detailed description of the life cycle parameters, adaptive behavior of nauplii and population dynamics in Acanthocyclops americanus compared to those in two other native Acanthocyclops species (Acanthocyclops vernalis and A. robustus), provides a possible history of the biological invasion of A. americanus in the Palearctic. Special attention is paid to the climate-dependent mechanism of the expansion of its range into the north and far east of Asia. The introduction of the A.americanus into small lakes in Great Britain resulted in the dominance of this species in the summer plankton. In many high-trophic reservoirs in Belgium, France and Spain, as well as in newly built reservoirs in Europe, this species has become the only representative of crustacean zooplankton in the warm season. This has led to a significant transformation of the trophic webs of these reservoirs. The rapid dispersal of the invasive species, which was demonstrated by A. americanus in the last century, can make it difficult, and in some cases even impossible to study the historical reasons for the formation of the fauna of other invertebrates associated with such events including the movement of continents and the evolution of the Tethys Sea.

Tectonic Evolution of Southern part of the Mesopotamian Foredeep Basin

This study investigated the tectonic evolution of the southern part of the MesopotamianForedeep basin. Subsidence and sedimentation rates were calculated for six oil wellsdistributed on the tectonic subzones of the sedimentary basin through the use of restoredthickness rates according to Backstripping Method for Cretaceous and Tertiary sequences. Theconsequence of this study indicates the subsidence and sedimentation rates changing verticallyand laterally through geologic time. As shown, the sequences of Albain subcycle are widesubsidence and sedimentation rates especially for the Mauddud Formation at the Am-1wellwhich located in the eastern part of the sedimentary basin (Tigris subzone), as well as for thesequences of Cenomanian-Early Turonian subcycle especially for the Ahmadi and Mishrifformations were increase in subsidence and sedimentation rate toward (Am-2 and Mj-3) wells.Both wells located within the Tigris and the eastern part of Zubair subzone. This is inaccordance with the closure of the South Tethys Sea because of the influences of the Austrianand Subhersynian orogenies. Three unconformity surfaces determine clearly in the depositinalbasin of incompatibility during the Early Turonian, Danian and Oligocene epochs. Thoseunconformities affects all tectonic subzones except for the Am-1well where it was notinfluences by the unconformity during the Oligocene epoch. The subsidence and sedimentationprocess continued at high rates, reflecting the large thickness of the eastern part of the basin inthe Tigris subzone area. Sedimentation rates augment significantly at the well (AG-19), whichindicates the effect of faults on the Tigris subzone. This affects the degree of maturation andthe source of hydrocarbons in the sedimentary basin.

Drilling the Aptian–Albian of the Sergipe–Alagoas Basin, Brazil: paleobiogeographic and paleoceanographic studies in the South Atlantic

The Aptian–Albian interval is characterized by significant paleoclimatic, paleoceanographic, and paleogeographic changes, which in turn affected the distribution and evolution of marine ecosystems. Despite the importance of such studies, there have been few correlations between Aptian–Albian sections of the Tethys Sea and those of the South Atlantic Ocean. This interval, including the Aptian–Albian transition, is preserved in the deposits of the Riachuelo Formation (Sergipe–Alagoas Basin, Brazil) located in the South Atlantic Ocean; therefore, this location was chosen for drilling four new cores. The goals of this paper are as follows: (1) to explain the drilling operation carried out in the deposits of the Riachuelo Formation and the methods used; (2) to present a brief lithostratigraphic characterization of the holes and the paleomagnetic data of core SER-03; and (3) to describe the high potential of the cores recovered for additional investigation in the future. The lithostratigraphic units of the SER-01 core consist mainly of coarse- to fine-grained sandstone, shales, marls, and mudstones; the SER-02 core was excluded due to low recovery; the SER-03 core is mainly composed of fine-grained sediments (shale, marls, and packstone) and bears some ammonite shells; the lithology of core SER-04 is mainly sandstones. Magnetic susceptibility values (χlf and χhf) and frequency-dependent susceptibility (χfd) data suggest that the section is located within the Cretaceous Normal Superchron. Future studies on these cores integrating micropaleontological, paleoichnological, geochemical, stratigraphic, and paleomagnetic (e.g., relative intensity) data will allow for a better understanding of paleoceanographic and paleogeographic events related to the early evolution of the South Atlantic Ocean and how these events correlate to similar events in Tethyan sections.

Phylogenomics and Historical Biogeography of Seahorses, Dragonets, Goatfishes, and Allies (Teleostei: Syngnatharia): Assessing Factors Driving Uncertainty in Biogeographic Inferences

The charismatic trumpetfishes, goatfishes, dragonets, flying gurnards, seahorses, and pipefishes encompass a recently defined yet extraordinarily diverse clade of percomorph fishes—the series Syngnatharia. This group is widely distributed in tropical and warm-temperate regions, with a great proportion of its extant diversity occurring in the Indo-Pacific. Because most syngnatharians feature long-range dispersal capabilities, tracing their biogeographic origins is challenging. Here, we applied an integrative phylogenomic approach to elucidate the evolutionary biogeography of syngnatharians. We built upon a recently published phylogenomic study that examined ultraconserved elements by adding 62 species (total 169 species) and one family (Draconettidae), to cover ca. 25% of the species diversity and all 10 families in the group. We inferred a set of time-calibrated trees and conducted ancestral range estimations. We also examined the sensitivity of these analyses to phylogenetic uncertainty (estimated from multiple genomic subsets), area delimitation, and biogeographic models that include or exclude the jump-dispersal parameter (j). Of the three factors examined, we found that the j parameter has the strongest effect in ancestral range estimates, followed by number of areas defined, and tree topology and divergence times. After accounting for these uncertainties, our results reveal that syngnatharians originated in the ancient Tethys Sea ca. 87 Ma (84–94 Ma; Late Cretaceous) and subsequently occupied the Indo-Pacific. Throughout syngnatharian history, multiple independent lineages colonized the eastern Pacific (6–8 times) and the Atlantic (6–14 times) from their center of origin, with most events taking place following an east-to-west route prior to the closure of the Tethys Seaway ca. 12–18 Ma. Ultimately, our study highlights the importance of accounting for different factors generating uncertainty in macroevolutionary and biogeographic inferences.

A new thermosbaenacean of the genus Tethysbaena (Peracarida, Thermosbaenacea, Monodellidae) from Socotra Island, Yemen

A new species of the thermosbaenacean genus Tethysbaena Wagner, 1994 (Crustacea: Peracarida: Thermosbaenacea) is described based on females from a freshwater cave lake and a brackish coastal well on Socotra Island (Yemen) as Tethysbaena dioscorida n. sp. It is the first representative of the Thermosbaenacea that is described from the Socotra Archipelago and the first member of the order known from an Indian Ocean island. The new species is the eighth known member of what is considered the “Tethysbaena relicta” species-group, which is known from Oman (four species), Somalia (one species), Israel (two species) and now Socotra Island (one species). The new species shows closest morphological affinities with T. barbatula Wagner, 2020 from Oman. We suggest that the speciation in this well-defined species-group is due to regressions of the Tethys Sea and the appearance of dry land since the Oligocene-Miocene boundary to the present time, forming major barriers and creating isolated populations of the ancestral species. Also the potential biocrisis in Socotra as a result of developmental activities during the last decades is mentioned, which may affect the subterranean faunas in particular in coastal areas, exemplified by the destruction of one of only two localities where the new species was found.