Large Taxa Research Articles

Mosasaurids Bare the Teeth: An Extraordinary Ecological Disparity in the Phosphates of Morocco Just Prior to the K/Pg Crisis

Mosasaurid teeth are abundant in the fossil record and often diagnostic to low taxonomic levels, allowing to document the taxonomic diversity and ecological disparity through time and with fewer biases than in other marine reptiles. The upper Maastrichtian Phosphates of Morocco, with at least fifteen coeval species representing a wide range of sizes and morphologies, undoubtedly represent the richest outcrop in the world for this clade of iconic Mesozoic squamates and one of the richest known marine tetrapod assemblages. Until now, the methods used to link tooth morphology to diets in marine amniotes were mainly qualitative in nature. Here, using the dental morphology of mosasaurids from Morocco, we combine two complementary approaches—a thorough comparative anatomical description and 2D/3D geometric morphometry—to quantitatively categorize the main functions of these teeth during feeding processes and infer diet preferences and niche-partitioning of these apex predators. Our results from combining these two approaches show the following: (1) Mosasaurids from the upper Maastrichtian Phosphates of Morocco occupy the majority of dental guilds ever colonized by Mesozoic marine reptiles. (2) As seen elsewhere in the Maastrichtian, mosasaurines dominate the regional mosasaurid assemblage, exhibiting the greatest taxonomic diversity (two-thirds of the species) and the largest range of morphologies, body sizes (2 m to more than 10 m) and ecological disparities (participating in nearly all predatory ecological guilds); strikingly, mosasaurines did not developed flesh piercers and, conversely, are the only ones to include durophagous species. (3) Halisaurines, though known by species of very different sizes (small versus large) and cranial morphologies (gracile versus robust), maintain a single tooth shape (piercer). (4) Plioplatecarpines were medium-size cutters and piercers, known by very morphologically diverging species. (5) Tylosaurines currently remain scarce, represented by a very large generalist species; they were largely replaced by mosasaurines as apex predators over the course of the Maastrichtian, as observed elsewhere. Also, when comparing tooth shapes with body sizes, the largest taxa (>8 m long) occupied a restricted area of tooth shapes (generalist, durophagous), whereas small and medium-sized species (<8 m long) range across all of them (generalists, durophagous, cutters, piercers). In other words, and probably related to the specificities and advantages of biomechanical resistance, apex predators are never dedicated piercers, micro-predators are conversely never generalists, and meso-predators show the widest range of dental adaptations. These diversities and disparities strongly suggest that Tethyan mosasaurids evolved strong niche-partitioning in the shallow marine environment of the upper Maastrichtian Phosphates of Morocco. Such a high diversity sensu lato just prior to the K/Pg biological crisis suggests that their extinction was rather sudden, though the exact causes of their extinction remain unknown. Finally, Gavialimimus Strong et al., 2020 is systematically reassigned to Gavialimimus ptychodon (Arambourg, 1952), and an emended diagnosis (for teeth and dentition) is proposed for this species.

Same rule, different genes: Blimp1 is a pair-rule gene in the milkweed bug Oncopeltus fasciatus.

Morphological features of organismal body plans are often highly conserved within large taxa. For example, segmentation is a shared and defining feature of all insects. Screens in Drosophila identified genes responsible for the development of body segments, including the "pair-rule" genes (PRGs), which subdivide embryos into double-segment units in a previously unexpected pre-patterning step. Here we show that the milkweed bug Oncopeltus fasciatus also uses a pair rule for embryo subdivision but Oncopeltus employs different genes for this process. We identified the gene Blimp1 as an Oncopeltus PRG based on its expression pattern, tested its function with RNA interference and CRISPR-Cas9, and generated the first PR mutant in this species. Although it does not have PR function in Drosophila, like Drosophila PRGs, Blimp1 encodes a transcription factor required for embryonic viability. Thus, pair-rule subdivision of the insect body plan is more highly conserved than the factors mediating this process, suggesting a developmental constraint on this pre-patterning step.

Rediscovery of Murex asperrimus Lamarck, 1822

The large Caribbean muricid originally named Murex asperrimus Lamarck, 1822 (non Gmelin, 1791), and illustrated by Kiener (1881), like many mollusks named in that era, was only given the general locality of “West Indes” in its description. The actual locality of this large and impressive taxon was never published, and it became a lost taxon. Since it was obscure, and specimens were not commonly known it has been unceremoniously synonymized with Phyllonotus pomum (Gmelin, 1791) (see Abbott, 1974). Recently, five specimens of this lost taxon were live collected in the Dominican Republic, ranging in length from 73.8 to 87.0 mm. This taxonomic note removes the taxon from synonymy, elevates it to full species level as Phyllonotus asperrimus (Lamarck, 1822), and fixes its type locality as the Dominican Republic

Visual fields, foraging and collision vulnerability in gulls (Laridae)

Wide variation in visual field configuration has been recorded among avian species and it is hypothesized that this variation is driven primarily by foraging ecology and predator detection. It has also been shown that visual field configurations can render some species more vulnerable to collisions with human artefacts that extend into open airspace, such as power lines and wind turbines. Visual fields have three main components: the monocular fields describe the extent of the world seen by each eye, the binocular field describes the region where the monocular fields overlap, and the blind area describes the region in which no vision is provided. Among birds, the topography of the binocular field, and the extent and position of the blind area, show considerable interspecific variation. Although Laridae (gulls, terns, skimmers) are a large and cosmopolitan taxon, visual field characteristics of only one species, Black Skimmer Rynchops niger, have been determined. However, skimmers are distinct from other Laridae species because they use a specialized foraging technique based upon tactile cues. We determined visual fields in three species of gulls (European Herring Gulls Larus argentatus, Lesser Black‐backed Gulls Larus fuscus, Black‐legged Kittiwakes Rissa tridactyla), and found that they show the key characteristics associated with visually guided foraging. However, the binocular field does not extend through the full height of the frontal field. This results in a blind sector, which can project in the direction of flight when gulls pitch their heads sufficiently far forwards to visually search the surface below. This could render gulls vulnerable to collisions with anthropogenic structures (power lines, wind turbines) that extend into the open airspace. Photographs show that gulls in level flight do pitch their heads forward sufficiently to render them almost blind in the direction of travel, and further work on the head positions adopted by gulls in flight are recommended. The visual field of skimmers differs markedly from those of gulls. Their binocular field topography is interpreted as functioning in the control of bill position when skimming (flying just above the water surface with the elongated, blade‐like, rhamphotheca of the mandible extending through the water surface). Skimmers also have a blind area, which projects forwards in the direction of travel when skimming. This can be associated with the vulnerability of skimmers to collisions with objects that extend just above the water surface.

PUPpy: a primer design pipeline for substrain-level microbial detection and absolute quantification.

Profiling microbial communities at high resolution and with absolute quantification is essential to uncover hidden ecological interactions within microbial ecosystems. Nevertheless, achieving resolved and quantitative investigations has been elusive due to methodological limitations in distinguishing and quantifying highly related microbes. Here, we describe Phylogenetically Unique Primers in python (PUPpy), an automated computational pipeline to design taxon-specific primers within defined microbial communities. Taxon-specific primers can be used to selectively detect and quantify individual microbes and larger taxa within a microbial community. PUPpy achieves substrain-level specificity without the need for computationally intensive databases and prioritizes user-friendliness by enabling both terminal and graphical user interface applications. Altogether, PUPpy enables fast, inexpensive, and highly accurate perspectives into microbial ecosystems, supporting the characterization of bacterial communities in both in vitro and complex microbiota settings.

Synallactesmcdanieli sp. nov., a new species of sea cucumber from British Columbia, Canada and the Gulf of Alaska, USA (Holothuroidea, Synallactida).

The family Synallactidae comprises mostly deep-sea forms and is the least-studied large taxon amongst deep-sea cucumbers. They are part of the abyssal megafauna and play an important role in modifying the sediment landscape and structuring the communities that live within it. The family embraces the genus Synallactes, which contains approximately twenty-five species from the Pacific, Atlantic (six species), Indian (seven species) and Antarctic Oceans (one species). Synallactesmcdanieli sp. nov. is described from the Northeast Pacific, Knight Inlet, British Columbia, Canada to Kodiak Island, Gulf of Alaska, USA, at depths from 21 to 438 m. This new species is unique amongst the species of the genus Synallactes because of the number and arrangement of dorsal papillae, number of Polian vesicles, together with the entire ossicle arrangement. In addition, this species has the shallowest bathymetric distribution ever recorded for this genus.

Studies in the Tubiflorae of Nagpur III. a Carpological Study

The paper presents results of a carpological study of the Tubiflorae of Nagpur based on author's personal acquaintance with more than 150 local species belonging to fourteen out of fifteen Indian plant families of the order. The "syncarpellous, epichlamydous" fruit has a persistent calyx that often exhibits a diagnostic form. Drupe, berry, capsule and schizocarp are the four principal types. Nine families may be broadly classed as "monocarpi" and the remaining five as "bicarpic". Distribution of these fruit types in the order offers no clue to their relative antiquity. While a broad correlation may be seen between fruit type and habit, exceptions are not wanting. Taxonomic value of fruit characters and inadequacies in the existing system of classification of fruits have been discussed. While existence throughout the order of a fundamentally uniform fruit-type adds weight to the view that "the Tubiflorae form a natural group", the several variations of this type indicate lines of specialisation within this large taxon.

A new ornithopod from the Upper Cretaceous (Huincul Formation) of northwestern Patagonia, Argentina: Implications on elasmarian postcranial anatomy

The aim of the present contribution is to describe the first ornithischian species from the Huincul Formation (Cenomanian-Turonian, Upper Cretaceous) at the Pueblo Blanco Natural Reserve, Río Negro province, Argentina. The new species, named Chakisaurus nekul gen. et sp. nov., can be comfortably included among elasmarian ornithopods. The new species shows humeral anatomy that is congruent with smaller members of the clade (e.g. Anabisetia, Notohypsilophodon), and differs from larger taxa (e.g. Talenkauen, Mahuidacursor) which show humeral features probably related with graviportal habits, such as lack of shaft torsion and a distally located deltopectoral crest. This indicates that graviportal habits were probably acquired independently in elasmarians from other large-sized taxa, such as hadrosauroids. Caudal vertebrae of the new species also show a unique combination of characters shared with other elasmarians, which are absent in previously known ornithopods. These features indicate that some elasmarians had a protonic tail posture, which is unknown in other ornithischians and was previously considered unique to derived titanosaurian sauropods. The shape of transverse processes and neural spines of caudal vertebrae indicate that at least some elasmarians had improved cursorial habilities, that were convergently acquired by selected theropod clades.

To and fro in the archipelago: Repeated inter-island dispersal and New Guinea’s orogeny affect diversification of Delias, the world’s largest butterfly genus

The world’s largest butterfly genus Delias, commonly known as Jezebels, comprises ca. 251 species found throughout Asia, Australia, and Melanesia. Most species are endemic to islands in the Indo-Australian Archipelago or to New Guinea and nearby islands in Melanesia, and many species are restricted to montane habitats over 1200 m. We inferred an extensively sampled and well-supported molecular phylogeny of the group to better understand the spatial and temporal dimensions of its diversification. The remarkable diversity of Delias evolved in just ca. 15–16 Myr (crown age). The most recent common ancestor of a clade with most of the species dispersed out of New Guinea ca. 14 Mya, but at least six subsequently diverging lineages dispersed back to the island. Diversification was associated with frequent dispersal of lineages among the islands of the Indo-Australian Archipelago, and the divergence of sister taxa on a single landmass was rare and occurred only on the largest islands, most notably on New Guinea. We conclude that frequent inter-island dispersal during the Neogene—likely facilitated by frequent sea level change—sparked much diversification during that period. Many extant New Guinea lineages started diversifying 5 Mya, suggesting that orogeny facilitated their diversification. Our results largely agree with the most recently proposed species group classification system, and we use our large taxon sample to extend this system to all described species. Finally, we summarize recent insights to speculate how wing pattern evolution, mimicry, and sexual selection might also contribute to these butterflies’ rapid speciation and diversification.

Functional annotation of a divergent genome using sequence and structure-based similarity

BackgroundMicrosporidia are a large taxon of intracellular pathogens characterized by extraordinarily streamlined genomes with unusually high sequence divergence and many species-specific adaptations. These unique factors pose challenges for traditional genome annotation methods based on sequence similarity. As a result, many of the microsporidian genomes sequenced to date contain numerous genes of unknown function. Recent innovations in rapid and accurate structure prediction and comparison, together with the growing amount of data in structural databases, provide new opportunities to assist in the functional annotation of newly sequenced genomes.ResultsIn this study, we established a workflow that combines sequence and structure-based functional gene annotation approaches employing a ChimeraX plugin named ANNOTEX (Annotation Extension for ChimeraX), allowing for visual inspection and manual curation. We employed this workflow on a high-quality telomere-to-telomere sequenced tetraploid genome of Vairimorpha necatrix. First, the 3080 predicted protein-coding DNA sequences, of which 89% were confirmed with RNA sequencing data, were used as input. Next, ColabFold was used to create protein structure predictions, followed by a Foldseek search for structural matching to the PDB and AlphaFold databases. The subsequent manual curation, using sequence and structure-based hits, increased the accuracy and quality of the functional genome annotation compared to results using only traditional annotation tools. Our workflow resulted in a comprehensive description of the V. necatrix genome, along with a structural summary of the most prevalent protein groups, such as the ricin B lectin family. In addition, and to test our tool, we identified the functions of several previously uncharacterized Encephalitozoon cuniculi genes.ConclusionWe provide a new functional annotation tool for divergent organisms and employ it on a newly sequenced, high-quality microsporidian genome to shed light on this uncharacterized intracellular pathogen of Lepidoptera. The addition of a structure-based annotation approach can serve as a valuable template for studying other microsporidian or similarly divergent species.

Structure and Trophic Characteristics of Zooplankton Communities of the East Siberian Sea

Research on the structure and trophic characteristics of zooplankton communities of the East Siberian Sea (ESS) was performed within the program “Marine Ecosystems of the Siberian Arctic” during cruise 69 of the R/V Akademik Mstislav Keldysh. The material was collected on two quasimeridional transects conducted in the latitudinal range ~71°00′–75°30′ N from the inner shelf adjacent to the Indigirka and Kolyma outfalls to the outer shelf during September 5–9, 2017. The list of species and larger taxa, as well as their biomass and trophic characteristics, are presented, and the peculiarities of cross-shelf distribution in relation to the conditions of the pelagic environment are described. The obtained estimates of the mezoplankton biomass in the ESS are on the whole within the range typical of the rest of the Siberian Seas in summer–fall. It has been established that mezoplankton communities of the western and eastern ESS significantly differ in quantitative characteristics, the role of dominant species and taxonomic groups in biomass, grazing impact of mesoplankton on the phytoplankton biomass and production, and features of the cross-shelf distribution of these characteristics. The boundary between the communities with different structural functional characteristics is located approximately at 160°–163° E. A conclusion is made that analysis of climatic and seasonal changes in ESS mezoplankton should be examined with allowance for the principal differences between pelagic biotopes and communities of the western and eastern parts of the basin.

Below-ground pitfall traps for standardised monitoring of soil mesofauna: Design and comparison to Berlese/Tullgren funnels

Sampling of soil mesofauna has been traditionally carried out with Berlese/Tullgren extractions, a century old technique. However, sampling methods involving the extractions of soil are becoming increasingly difficult to implement and standardise due to the lack of commercially available equipment. Moreover, they are poorly suited to repeated sampling in the same locations and underestimate more mobile taxa.Below-ground (hypogean) pitfall trapping is a promising new technique that up to now was only attempted with bulky custom-manufactured tools. In the present work we test a cheap and easily deployable setup made using standard pipe fittings.The new design was compared across different environments with Berlese/Tullgren extractions in order to ascertain whether they produce similar species lists and detect the same environment-induced changes in communities. The two trap types were found to yield structurally different assemblages, with the new design producing significantly higher abundance and diversity of springtails and larger taxa. Beta-diversity profiles resulted however perfectly comparable, characterising the same pattern of dissimilarities. In addition, a new method is proposed to use the two sampling types in combination to estimate the dispersal of soil organisms.Below-ground pitfall traps have the potential to complement Berlese extractions for reliable and standardised monitoring of soil arthropods, thanks to their effectiveness, low cost and ease of operation.

New heterodont odontocetes from the Oligocene Pysht Formation in Washington State, U.S.A., and a reevaluation of Simocetidae (Cetacea, Odontoceti).

Odontocetes first appeared in the fossil record by the early Oligocene, and their early evolutionary history can provide clues as to how some of their unique adaptations, such as echolocation, evolved. Here, three new specimens from the early to late Oligocene Pysht Formation are described further increasing our understanding of the richness and diversity of early odontocetes, particularly for the North Pacific. Phylogenetic analysis shows that the new specimens are part of a more inclusive, redefined Simocetidae, which now includes Simocetus rayi, Olympicetus sp. 1, Olympicetus avitus, O. thalassodon sp. nov., and a large unnamed taxon (Simocetidae gen. et sp. A), all part of a North Pacific clade that represents one of the earliest diverging groups of odontocetes. Amongst these, Olympicetus thalassodon sp. nov. represents one of the best known simocetids, offering new information on the cranial and dental morphology of early odontocetes. Furthermore, the inclusion of CCNHM 1000, here considered to represent a neonate of Olympicetus sp., as part of the Simocetidae, suggests that members of this group may not have had the capability of ultrasonic hearing, at least during their early ontogenetic stages. Based on the new specimens, the dentition of simocetids is interpreted as being plesiomorphic, with a tooth count more akin to that of basilosaurids and early toothed mysticetes, while other features of the skull and hyoid suggest various forms of prey acquisition, including raptorial or combined feeding in Olympicetus spp., and suction feeding in Simocetus. Finally, body size estimates show that small to moderately large taxa are present in Simocetidae, with the largest taxon represented by Simocetidae gen. et sp. A with an estimated body length of 3 m, which places it as the largest known simocetid, and amongst the largest Oligocene odontocetes. The new specimens described here add to a growing list of Oligocene marine tetrapods from the North Pacific, further promoting faunistic comparisons across other contemporaneous and younger assemblages, that will allow for an improved understanding of the evolution of marine faunas in the region.

Phylogeny and diversification of planthoppers (Hemiptera: Fulgoromorpha) based on a comprehensive molecular dataset and large taxon sampling

Our understanding of the evolution of Fulgoromorpha (Insects, Hemiptera) has relied on molecular studies that have only considered either a limited number of taxa where all the families were not represented simultaneously, or a reduced number of genes.The absence of a global analysis comparing all the available data has thus led to significant biases in the analyzes, as evidenced by the incongruence of the results reported for planthopper phylogeny. Here we provide a phylogenetic and dating analysis of the Fulgoromorpha with a large sampling of 531 ingroup taxa, representing about 80% of the currently described suprageneric taxonomic diversity in this group. This study is based on most of the molecular sequences available to date and duly verified, for a set of nuclear and mitochondrial genes from a taxonomic sampling as complete as possible. The most significant results of our study are: (1) the unexpected paraphyly of Delphacidae whose Protodelphacida seem more related to Cixiidae than to other Delphacidae;(2) the group Meenoplidae-Kinnaridae recovered sister to the remaining Fulgoroidea families; (3) the early branching node of Tettigometridae sister of all the other families;(4) the Achilidae-Derbidae clade with Achilidae Plectoderini including Achilixiidae recovered as monophyletic as well as theFulgoridae-Dictyopharidae clade; and (5) the Tropiduchidae placed sister to the other so called ‘higher’ families (sec. Shcherbakov, 2006).Our divergence times analysis, calibrated with a set of duly verified fossils, suggests that the first diversification of planthoppers occurred in the Early Triassic around 240 Mya and those of the superfamilies Delphacoidea and Fulgoroidea in the Middle-Late Triassic around 210 Mya and 230 Mya, respectively. By the end of the Jurassic, all major planthopper lineages were originated, and all families, around 125 Mya, might havebeen driven in their distribution and evolution (in their first subfamilial divisions) by the geographical constraints of the Gondwanan break-up.Rapid evolutionary radiations occurred particularly in Fulgoridae around 125–130 Mya. Our results stress the importance of the good quality of the sequences used in the molecular analyzes and the primordial importance of a large sampling when analyzing the phylogeny of the group.

Changes in the composition of the intestinal microbiota, associated with IL-6 deficiency

Interleukin-6 (IL-6) is a broad-spectrum cytokine involved in the immune, nervous, and endocrine regulation of many biological processes. IL-6 performs both homeostatic and pathogenic functions. It is one of the key factors in the cytokine storm in COVID-19, and it also controls the production of acute phase proteins during inflammation. IL-6 is involved in the maintenance of intestinal homeostasis and is required for both the induction of inflammation and the repair of the injured intestinal tissue. In turn, the commensal microbiota, represented by eukaryotes, prokaryotes, and viruses, is one of the key factors modulating the immune response in the gut. The predominance of certain groups of commensal microorganisms is associated with the development of intestinal inflammation, while probiotics and antibiotics are successfully used to control inflammatory bowel disease. IL-6 is also necessary to maintain the barrier function of the intestine by modulating the proliferation of intestinal cells, which is necessary for their timely renewal both in homeostasis and inflammation. It has been established that the genetic inactivation of IL6 contributes to the development of intestinal inflammation, while the involvement of IL-6 in the control of the gut microbiota composition remains unclear. To investigate this issue, we analyzed stool samples from wild-type naive mice and mice deficient in IL6 (IL-6 KO) generated on the C57Bl/6 genetic background. It has been determined that IL-6 KO shows significant changes in some taxonomic groups of commensals, which may explain the sensitivity of IL-6 KO to the development of colitis. Interestingly, the relative contents of Firmicutes and Clostridiales are significantly reduced, whereas Bacteroides are increased in IL-6 KO as compared with wild-type mice. Our data on the reduction of Firmicutes, Lactobacillaceae, and other large taxa in IL-6 deficient mice suggest that the microbiota composition of IL-6 KO mice is somewhat similar to that of mice with chronic intestinal inflammation. Our study serves as a perspective for further research on the contribution of IL-6-mediated changes in the microbiota composition to the maintenance of intestinal homeostasis and the development of chronic gut inflammation.

Improvement of the description of ostracods of the family TRACHYLEBERIDINAE

Introduction. The definition of criteria for separating closely related species of representatives of the genus Cythereis is currently incomplete. Ostracods of this genus have wide intraspecific variability and high adaptability to changing living conditions. These factors make it difficult to use these ostracod species for regional stratigraphic correlation. In addition to the selection of criteria for species separation, there is a problem of the imperfection of the terminological apparatus for describing ostracods, which complicates the description of species and omits potentially important information for the separation of related species. Analysis of previous publications. Numerous works are devoted to the issue of the development of the terminological apparatus for describing ostracods, however, qualitative methods of description are inherent only to certain large taxa, where a separate method of description has been developed for each taxon. Ostracods of the genus Cythereis are widespread in the Cretaceous Tethys. Their wide variability is considered by various authors often without taking into account intraspecific variability and adaptation, which leads to the selection of subspecies or ignoring variability. Materials and methods. Numerous ostracods of the species Cythereis hirsuta Damotte&Grosdidier from the Late Cenomanian and Cythereis ornatissima (Reuss) from the Turonian of Ukraine were used in the work. Ostracods were selected from different deposits according to the conditions of origin. Results and discussion. The paper describes in detail the morphology of ostracods of the genus Cythereis with qualitative characteristics of morphological elements. The ontogenetic changes of the two species and the change in morphology depending on the conditions of existence are also described. The change in the morphology of juvenile forms depending on the conditions of existence is described separately. Conclusions. Based on the study and description of numerous paleontological materials, a number of refinements were proposed to the descriptive characteristics of the morphological elements of ostracod valves of members of the family TRACHYLEBERIDINAE Sylvester-Bradley, 1948 and the genus Cythereis in particular. The proposed clarifications regarding the morphology of the mesosculpture made it possible to describe in detail the ontogenetic changes of the studied species and their differences in adult stages depending on the facial conditions of existence. It should be noted that a detailed scheme for describing the morphology of mesosculpture is proposed for the first time in the literature. The paleontological description of numerous materials from the Middle Cretaceous of Ukraine allowed to establish the morphological elements that are of primary importance for the separation of related species within the genus. The analysis of these elements suggests that some of the similar species from the outcrops of Europe and Asia are actually other species. The question of their phylogenetic ties can be solved under the condition of studying ontogenesis and expanding the geography of research. Based on this, the validity of the names of the studied species from the territory of Ukraine is also contradictory to the actual comparison with the holotype collection.

Diet Composition and Reproductive Properties of European Conger, Conger conger (Congridae) in the Turkish Aegean Sea

The diet composition and reproductive properties of European conger, Conger conger (Linnaeus, 1758) were investigated from the Aegean Sea of Türkiye to compare our data with those from other regions of the Mediterranean Sea and throughout all four seasons. A total of 100 individuals were examined. Totally 19 prey taxa belonging to three large taxon (cephalopods, crustaceans, and fishes) were identified in the stomachs of European conger. According to the relative significance index the crustaceans were dominant food in diet of individuals smaller than 50 cm, while fish prevailed in diet of fish with length between 75 and 100 cm. Histological analysis of 80 gonads showed that all individuals were immature (20%) and maturuing females (80%). Maturing females were with oocytes in the previtellogenic (16% of all fishes) and early vitellogenic phases (64%). The oocyte diameters were 80–476 μm at previtellogenic (diameter range 80–240 μm) and 245–476 μm at early vitellogenic individuals. Immature females had the gonads with the oocyte diameter 30 μm

MONITORING OF SEDIMENT POLLUTION FOR VARIOUS WATER BODIES IN THE UPPER VOLGA REGION

The problem of water body pollution with heavy metals is still relevant. From the viewpoint of technogenic load, the most hazardous pollutants are elements Hg, Cd, Zn, Pb, Cu, Cr, Co, Ni, Fe, Mn, and As. To systematize the research, the objects of different hierarchical levels were identified. Based on many years of experimental work, contamination of sediments with heavy metals was assessed for the Upper Volga system, i.e., Lake Seliger, an unregulated section of the Upper Volga, Ivankovskoe and Uglichskoe reservoirs. The largest taxon is the basin of the reservoir with the adjoining watershed area with cities and towns located on it, tributaries of various orders, smaller elements of natural and natural-technogenic relief. Urban and settlement agglomerations located on the coasts of reservoirs and unregulated areas or within watersheds are smaller in area, but no less significant in their role in water body pollution. Small rivers contribute to pollution/purification, which can contribute to the flow of both clean and polluted silty material into large watercourses. Different areal and temporal survey modes are offered for taxa of different hierarchy. The practical results of studies of the content in sediments of the listed objects of heavy metals – Cr, Co, Ni, Zn, Cd, Pb, As, Fe and Mn are presented. Described or provided references to the methods used in the experiments. The general picture of pollution is presented and the tendencies of its change in space and time are noted.

Drilling predation on Early Jurassic bivalves and behavioral patterns of the presumed gastropod predator—evidence from Pliensbachian soft-bottom deposits of northern Germany

AbstractDrilling predation is a common reason for mortality of benthic mollusks but did not become common until the late Mesozoic. The scarcity of drill holes in the early Mesozoic fossil record limits our understanding of the evolution of drilling behavior and its role on shaping early Mesozoic marine communities. Here, we use drilling traces on several bivalve taxa from the Lower Jurassic (Pliensbachian) marine soft-bottom deposits in northern Germany to explore behavioral patterns of the predator (e.g., site selectivity, change in site-selective behavior with age). Although none of the known drilling gastropod groups existed in the Pliensbachian, including the studied localities, the drill-hole morphology suggests that the predator was probably a gastropod. The ecology and identity of the target prey changes from a diverse array of epifaunal to infaunal taxa in older deposits to focus on a single, large, deep infaunal taxon, Gresslya intermedia, in younger deposits, suggesting a potential trend in prey selectivity over time. Spatial point pattern analysis of traces (SPPAT) reveals an aggregated pattern of drill holes on Gresslya, suggesting strong selectivity in drill-hole location. Drilling on a single large infaunal taxon and site selectivity are common patterns also inferred previously from the drilled deep infaunal Eothyasira from the Pliensbachian of southern Germany. In addition to the scarcity of predators, the highly specialized behavior of the early drilling predators, including strong prey selectivity in terms of prey identity and life habit, can partly explain the rarity of the early Mesozoic drill holes.

Bear or bear-dog? An enigmatic arctoid carnivoran from the late Eocene of Asia

Records of Paleogene arctoids are scarce in Asia, but there are abundant records in Europe and North America. In this study, we report a new arctoid taxon, Lonchocyon qiui gen. et sp. nov., from the late Eocene Baron Sog Formation of the Erlian Basin, Inner Mongolia, China. This is the first report of a relatively complete, large arctoid taxon from the Erlian Basin. The new taxon is characterized by its overall large size; a deep mandible with a marginal process and a rudimentary premasseteric fossa; and much-reduced premolars, including p4, sectorial carnassial m1 with basined talonid, and unreduced m2-3. Lonchocyon exhibits a combination of morphologies present in both amphicyonids and the early ursid hemicyonines. The mandibular force profiles suggest that Lonchocyon could have delivered powerful canine bites while subduing prey, like large felids do today, and it may have occupied a specialized ecological niche as a predator consuming both soft flesh and hard objects.