Feeding Traces Research Articles

A 2x2 Mimo Microstrip Patch Antenna Design For X-Band Applications Using Inverted Array Orientation Approach

Objective: The main goal of this research is to design and simulate a unique 2x2 multiple-input and multiple-output, (MIMO) Rectangular Microstrip Patch antenna (RMPA) using an inverted array orientation approach with keen interest in improving the radiation efficiency and performance characteristics of the X- band based antenna. Theoretical Framework: This work integrates principles from Electromagnetic theory, communication theory, and basic Microstrip antenna design concepts. The framework is built upon crucial design goals such as radiation efficiency, reliability, element orientation and compactness of the antenna elements. Method: This research adopted a design and simulation approach. All the antenna design modules and analysis were conducted using MATLAB R2023b simulator. Firstly, this work modelled and designed a unique single-element RMPA after iterations and optimisations of the antenna parameters to achieve enhanced performance. The achieved single element was used to model a 2x2 MIMO antenna with specified element spacing. The design applied an inverted element array orientation and streamlined feed trace mechanism to achieve a high gain and enhanced radiation efficiency. Results and Discussion: The unique antenna design recorded a return loss of -15.2 dB, directivity of 7.33 dB, bandwidth of 484.8 MHz, gain of 7.16 dB, VSWR of 1.41, and radiation efficiency of 96.2%. Further analysis on the designed MIMO antenna to ascertain the mutual coupling effect showed that Envelope Correlation Coefficient (ECC) values remained below 0.2 within the 10 GHz frequency band, representing good diversity and significantly reducing the mutual coupling effect between array elements. The Diversity Gain (DG) of 9.87 and 9.84 dB were obtained. These values are near the optimal value of 10 dB, which is diversity for MIMO applications. Research Implications: The findings show the viability of the proposed design based on the performance metrics considered when compared to the previously designed Microstrip Patch Antennas (MPA). Thus, the designed MIMO antenna is suggested for use in embedded wireless communication devices within 8-12 GHz frequency bands for X-band applications such as radar systems and WiMAX. Originality/Value: This study presents an innovative approach to improving the radiation efficiency of a designed 2x2 MIMO antenna. The work showed that enhancement of the radiation efficiency has a direct effect on the mutual coupling, which this work applied inverted orientation and streamlined feed trace method to minimise.

Understanding the role of Bacillus subtilis GEB1 in enhancing guava plant immunity against Meloidogyne enterolobii: A multifaceted approach

Guava root-knot nematode, Meloidogyne enterolobii has emerged as a significant threat to guava cultivation, impacting production worldwide. By integrating the molecular, histopathological and in silico approaches the current study explores the efficacy of Bacillus subtilis GEB1 in enhancing the resistance of guava against M. enterolobii. The gene expression studies reveal that guava plants treated with B. subtilis and challenged with nematodes at 72 h showed 2 fold increase in phytoene synthase, 2.1 fold increase in mitogen-activated protein kinase, 1.54 fold increase in phenylalanine ammonia-lyase and 1.82 fold increase in peroxidase genes when compared to untreated control. The Scanning electron microscope analysis of guava roots treated with B. subtilis revealed the presence of spores in the rhizoplane region which led to deter the invading nematodes. The comparative histological studies with guava roots treated with B. subtilis revealed lesser damage in the cortex, vascular regions with limited hypertrophy and hyperplasia, lesser adult females, and feeding traces with minimum root, stele and cortex diameter and thickness than those of untreated infested roots. Attempts were made to dock the plant functional proteins with B. subtilis peptides to understand their interaction. The results revealed that bacillobactin showed a greater binding affinity of −9.0 kcal/mol with phytoene synthase, plipstatin (−16.0 kcal/mol), and fengycin (−15.9 kcal/mol) with MAPK proteins of guava. Overall, the current study offers insight into the intricate mechanisms of plant-nematode-bacteria interactions and underscores the importance of B. subtilis GEB-1 as a biocontrol agent to combat Meloidogyne enterolobii infection in guava.

Diuqin lechiguanae gen. et sp. nov., a new unenlagiine (Theropoda: Paraves) from the Bajo de la Carpa Formation (Neuquén Group, Upper Cretaceous) of Neuquén Province, Patagonia, Argentina

BackgroundUnenlagiine paravians are among the most relevant Gondwanan theropod dinosaur clades for understanding the origin of birds, yet their fossil record remains incomplete, with most taxa being represented by fragmentary material and/or separated by lengthy temporal gaps, frustrating attempts to characterize unenlagiine evolution.Results and conclusionsHere we describe Diuqin lechiguanae gen. et sp. nov., a new unenlagiine taxon from the Upper Cretaceous (Santonian) Bajo de la Carpa Formation of the Neuquén Basin of Neuquén Province in northern Patagonia, Argentina that fills a substantial stratigraphic gap in the fossil record of these theropods. Although known only from a very incomplete postcranial skeleton, the preserved bones of Diuqin differ from corresponding elements in other unenlagiines, justifying the erection of the new taxon. Moreover, in several morphological aspects, the humerus of Diuqin appears intermediate between those of geologically older unenlagiines from the Neuquén Basin (e.g., Unenlagia spp. from the Turonian–Coniacian Portezuelo Formation) and that of the stratigraphically younger, larger-bodied Austroraptor cabazai from the Campanian–Maastrichtian Allen Formation. Consequently, the morphology of the new taxon appears to indicate a transitional stage in unenlagiine evolution. Phylogenetic analysis recovers Diuqin as a paravian with multiple plausible systematic positions, but the strongest affinity is with Unenlagiinae. The humerus of the new form exhibits subcircular punctures near its distal end that are interpreted as feeding traces most likely left by a conical-toothed crocodyliform, mammal, or theropod, the latter potentially corresponding to a megaraptorid or another unenlagiine individual. Thus, in addition to filling important morphological and temporal gaps in unenlagiine evolutionary history, the new taxon also offers information relating to the paleoecology of these theropods.

Palaeoecological significance of the trace fossil Circulichnis Vyalov, 1971 from the Carboniferous of the Donets Basin, Ukraine

The ichnogenus Circulichnis Vyalov is a horizontal a ring- or ellipse-shaped burrow and/or locomotion trace of an unknown producer, most likely an annelid or a “worm”, preserved on the bedding plane. This ichnogenus is known over a wide age interval (Ediacaran–Oligocene). Circulichnis demonstrates a wide ecological range and has been found in continental (Mermia ichnofacies), shelf, and relatively deep-water (turbidites) deposits. It is commonly interpreted as a sediment feeding trace, but the peculiarities of its formation remain somewhat mysterious, as it is unclear how the tracemaker reached the sediment surface, as lateral branches of the ring-shaped traces are extremely rare and have only been observed by a few researchers. A rather large specimen of Circulichnis montanus Vyalov, 1971 with a preserved lateral branch was found in the Mospyne Formation (upper Bashkirian, Lower Pennsylvanian) of the Donets Basin. This discovery confirmed the assumption made by Alfred Uchman and Bruno Ratazzi regarding the peculiarities of formation of Circulichnis. According to these authors, a single ring-shaped Circulichnis indicates an attempt to forage at a specific level in the sediment, while the lateral branches of Circulichnis are part of a vertical shaft leading to another level within the sediment. The study of Circulichnis montanus from the Donets Basin has confirmed that at least variant C of the Circulichnis formation scheme proposed by Uchman and Ratazzi is correct, i.e. the lateral branch is a horizontal or subhorizontal part of a generally vertical shaft. However, it is important to note that the correctness of variants A and B of the Uchman and Ratazzi scheme cannot be excluded. To answer this question unequivocally, new finds of well-preserved Circulichnis are necessary.

New Canadian amber deposit fills gap in fossil record near end-Cretaceous mass extinction

Amber preserves an exceptional record of tiny, soft-bodied organisms and chemical environmental signatures, elucidating the evolution of arthropod lineages and the diversity, ecology, and biogeochemistry of ancient ecosystems. However, globally, fossiliferous amber deposits are rare in the latest Cretaceous and surrounding the Cretaceous-Paleogene (K-Pg) mass extinction.1,2,3,4,5 This faunal gap limits our understanding of arthropod diversity and survival across the extinction boundary.2,6 Contrasting hypotheses propose that arthropods were either relatively unaffected by the K-Pg extinction or experienced a steady decline in diversity before the extinction event followed by rapid diversification in the Cenozoic.2,6 These hypotheses are primarily based on arthropod feeding traces on fossil leaves and time-calibrated molecular phylogenies, not direct observation of the fossil record.2,7 Here, we report a diverse amber assemblage from the Late Cretaceous (67.04± 0.16 Ma) of the Big Muddy Badlands, Canada. The new deposit fills a critical 16-million-year gap in the arthropod fossil record spanning the K-Pg mass extinction. Seven arthropod orders and at least 11 insect families have been recovered, making the Big Muddy amber deposit the most diverse arthropod assemblage near the K-Pg extinction. Amber chemistry and stable isotopes suggest the amber was produced by coniferous (Cupressaceae) trees in a subtropical swamp near remnants of the Western Interior Seaway. The unexpected abundance of ants from extant families and the virtual absence of arthropods from common, exclusively Cretaceous families suggests that Big Muddy amber may represent a yet unsampled Late Cretaceous environment and provides evidence of a faunal transition before the end of the Cretaceous.

Uniquely preserved gut contents illuminate trilobite palaeophysiology.

Trilobites are among the most iconic of fossils and formed a prominent component of marine ecosystems during most of their 270-million-year-long history from the early Cambrianperiod to the end Permianperiod1. More than 20,000 species have been described to date, with presumed lifestyles ranging from infaunal burrowing to a planktonic life in the water column2. Inferred trophic roles range from detritivores to predators, but all are based on indirect evidence such as body and gut morphology, modes of preservation and attributed feeding traces; no trilobite specimen with internal gut contents has been described3,4. Here we present the complete and fully itemized gut contents of an Ordovician trilobite, Bohemolichas incola, preserved three-dimensionally in a siliceous nodule and visualized by synchrotron microtomography. The tightly packed, almost continuous gut fill comprises partly fragmented calcareous shells indicating high feeding intensity. The lack of dissolution of the shells implies a neutral or alkaline environment along the entire length of the intestine supporting digestive enzymes comparable to those in modern crustaceans or chelicerates. Scavengers burrowing into the trilobite carcase targeted soft tissues below the glabella but avoided the gut, suggesting noxious conditions and possibly ongoing enzymatic activity.

Tapejarine pterosaur from the late Albian Paw Paw Formation of Texas, USA, with extensive feeding traces of multiple scavengers

ABSTRACT An incomplete right metacarpal IV of a pterosaur from the late Albian Paw Paw Formation of Texas, USA, is the second pterosaur from that formation and an important addition to the sparse pterosaur record of the Albian of North America. Although the proximal and distal ends are missing, what remains of the shaft is straight and slender with little taper, little anteroposterior compression, and a distinct distal neck, and indicates the individual was of modest size despite being fully mature, and on that basis the specimen is referred to the Tapejarinae and is the first record of that taxon in North America. The specimen exhibits numerous bite marks of various types that are interpreted as resulting from intense scavenging by at least two different shark species and perhaps a bony fish.

A new type of feeding trace caused by a donaciine beetle (Coleoptera, Chrysomelidae) on a leaf from the Paleocene of Menat (France)

The lacustrine Lagerstätte of Menat (Puy-de-Dôme, France) provides a unique window into the terrestrial Paleocene environments of Western Europe (Wedmann et al., 2018). It has shown an exceptional diversity of plants (leaves, flowers, seeds, pollen), and animals (vertebrates and arthropods, especially insects) (e.g., Piton, 1940). Wappler et al. (2009) made a first analysis of the animals-plants interactions. Recent extensive researches were made, allowing to collect an important set of leaves with numerous and diverse traces of activities, some of them being not previously recorded among the total of 1,130 specimens of leaves, fruits and flowers studied by Wappler et al. (2009). Among the new material, we found three curious sets of traces on a small leaf that do not correspond to anything previously listed by Labandeira et al. (2007). These traces can be attributed to the beetle subfamily Donaciinae (Chrysomelidae).

Effect of feed trace elements on eggs of five strains of laying hens and their health risk assessment.

Trace elements are essential for human nutrition, and their deficiencies or excesses are strongly associated with several diseases, such as cardiovascular ones. The current cross-sectional study investigated the concentration of essential trace elements (copper, non-metal selenium, iron, zinc, cobalt and manganese) in eggs and diets of five strains of laying hens. The yolk and albumen were analysed separately, and wet preparation was carried out following inductively coupled plasma-optical emission spectrometry detection. The target hazard quotients (THQs) for the non-carcinogenic disease were calculated by the United States environmental protection agency (USEPA) method. The highest concentrations of selenium, zinc and manganese were found in egg yolks of native hens (0.76, 44.22 and 6.52mg/kg, respectively). The highest amounts of copper and cobalt were recorded in the egg yolk of Lohman (2.07 and 0.023mg/kg, respectively). On the other hand, the egg yolk of Bovans contained the highest amount of iron (57.46mg/kg). Overall, the potential health risks were minimal, and the consumption of eggs was generally safe.

ASSESSING PALEOECOLOGICAL DATA RETENTION AMONG DISPARATE FIELD COLLECTION REGIMES: A CASE STUDY AT THE MYGATT-MOORE QUARRY (MORRISON FORMATION)

ABSTRACT Field work protocols in the recovery of vertebrate fossils can vary between sites, and also within sites, due to differing researcher goals. Disparate researcher priorities can affect the resulting collections in terms of species richness, size distribution, specimen completeness, taphonomic condition, and aesthetic value. We examined paleoecological data, in the form of bone surface modifications (e.g., abrasion, feeding traces, etc.), from a single site worked by multiple collectors to determine the sensitivity of this type of data to collector bias. We examined 2,368 fossils from the Mygatt-Moore Quarry and divided them into two cohorts: 2016–2019 (bulk collection under a single collector) and pre-2016 (mixed collectors and priorities). Frequencies of modified bone surfaces were then calculated in each cohort among the recovered specimens. However, the specimens within the cohorts were of unequal size, completeness, and amount of preserved surface area, making inferences of modified bone surface frequencies difficult. To correct for unequal morphologies and preservation, we estimated the percentage of altered surface area among specimens by overlaying photos with a 4.0 cm2 digital grid to create a digital set of equal sized fragments. With such a large dataset, we took a random 10% subsample of specimens from each cohort for the grid study. We estimated the sample size needed to accurately reflect the frequency of bone surface modifications by specimen and surface area for each cohort. Results show the recovery of modified bone surfaces between the two cohorts was highly disparate, and potentially sensitive to the effects of collector bias when using specimen-level data. However, frequencies based on estimates of surface area were much more consistent and appeared to equalize data between cohorts and showed little influence of collector bias on data recovery. Thus, the traditional method of calculating frequencies using specimen-level data may create an illusion of bias that is removed when frequencies are calculated from estimated bone surface area. We posit that the digital fragmentation method is more informative when comparing paleoecological traces between datasets and should be applied to fossil assemblages going forward, especially when collection protocols between assemblages are significantly different or unknown.

Effects of plant community and altitude on food composition of Cervus elaphus wallichii during the withered grass period on the Tibetan Plateau, China.

How Tibetan red deer (Cervus elaphus wallichii) acclimates to high altitude environment during the withered grass period is one of the challenges in maintaining their nutrient intake. It is an important basis to study the nutritional ecology of wild large ungulates in alpine ecosystems by investigating the changes in plant communities with altitude during the withered grass period and how these changes affect the food composition of Tibetan red deer. In this study, we selected the Tibetan red deer in Sangri County, Shannan region of Tibet as the research subject. We carried out field surveys on the altitude, plant communities, and feeding traces of the Tibetan red deer in March of 2021 and 2022 during the withered grass period on the Tibetan Plateau. Detrended correspondence analysis and canonical correspondence analysis were used to study altitudinal variations in plant communities and the regularity of food composition. The results showed that during the period of withered grass, Tibetan red deer ate primarily Salix daltoniana, Rosa macrophylla var. glandulifera and Dasiphora parvifolia. S. daltoniana accounted for more than 50% of the food composition, as the main food resources for red deer in withered grass period. In the low altitude area (4100-4300 m), plant community included Caragana versicolor, R. macrophylla and Berberis temolaica, and Tibetan red deer mainly ate R. macrophylla, C. versicolor and Artemisia wellbyi. In higher altitude area (4300-4600 m), plant community consisted of Rhododendron nivale, Rhododendron fragariiflorum, and Sibiraea angustata, and Tibetan red deer mainly fed on S. daltoniana, Salix obscura, and Carex littledalei. At different altitudes, the dominant plant species were the main food of Tibetan red deer. It is suggested that the changes of plant community composition with altitude directly affected food composition of Tibetan red deer, indicating different food composition patterns with altitude gradients.

Is the middle Cambrian Brooksella a hexactinellid sponge, trace fossil or pseudofossil?

First described as a medusoid jellyfish, the "star-shaped" Brooksella from the Conasauga shale Lagerstätten, Southeastern USA, was variously reconsidered as algae, feeding traces, gas bubbles, and most recently hexactinellid sponges. In this work, we present new morphological, chemical, and structural data to evaluate its hexactinellid affinities, as well as whether it could be a trace fossil or pseudofossil. External and cross-sectional surfaces, thin sections, X-ray computed tomography (CT) and micro-CT imaging, revealed no evidence that Brooksella is a hexactinellid sponge or a trace fossil. Although internally Brooksella contains abundant voids and variously orientated tubes consistent with multiple burrowing or bioeroding organisms, these structures have no relation to Brooksella's external lobe-like morphology. Furthermore, Brooksella has no pattern of growth comparable to the linear growth of early Paleozoic hexactinellids; rather, its growth is similar to syndepositional concretions. Lastly, Brooksella, except for its lobes and occasional central depression, is no different in microstructure to the silica concretions of the Conasauga Formation, strongly indicating it is a morphologically unusual endmember of the silica concretions of the formation. These findings highlight the need for thorough and accurate descriptions in Cambrian paleontology; wherein care must be taken to examine the full range of biotic and abiotic hypotheses for these compelling and unique fossils.

Analysis of the Anomalies in a Middle Eocene Shell of Neochelys (Pleurodira, Podocnemididae) from the Duero Basin (Zamora, Spain)

Turtle shells frequently exhibit anomalous osseous modifications on their surface which can sometimes compromise the survival of the organism. Nowadays, despite the large number of anomalies identified in both extant and extinct turtle shells, the etiology, as well as the pathogenesis, of the various osseous modifications remains unknown in most documented extinct representatives. In fact, the interpretation of these anomalies in most fossil turtles is often speculative, the great majority of anomalous osseous modifications being attributed to vertebrate feeding traces, without considering other potential causative agents. In this context, we herein re-analyzed the shell anomalies recognized in an individual determined as Neochelys sp. (Pleurodira, Podocnemididae) from the middle Eocene (Lutetian) of the El Tejar fossil site (Corrales del Vino, Zamora, Spain), previously proposed as traumatic injuries resulting from a crocodile attack. The re-evaluation of these osseous alterations through detailed physical examination, comparison through direct observation and from the literature on extant turtles, and the use of the files obtained from a computerized axial tomography scan, allows the proposal of diverse causal agents, none of them supporting the previous interpretation. In addition, information regarding the pathogenesis and stages of the healing of the shell anomalies studied herein is provided.

Polyplacophoran Feeding Traces on Mediterranean Pliocene Sirenian Bones: Insights on the Role of Grazing Bioeroders in Shallow-Marine Vertebrate Falls

Chitons (Polyplacophora) include some of the most conspicuous bioeroders of the present-day shallow seas. Abundant palaeontological evidence for the feeding activity of ancient chitons is preserved in the form of radular traces that are usually found on invertebrate shells and hardgrounds. We report on widespread grazing traces occurring on partial skeletons of the extinct sirenian Metaxytherium subapenninum from the Lower Pliocene (Zanclean) of Arcille (Grosseto Province, Tuscany, Italy). These distinctive ichnofossils are described under the ichnotaxonomic name Osteocallis leonardii isp. nov. and interpreted as reflecting substrate scraping by polyplacophorans. A scrutiny of palaeontological literature reveals that similar traces occur on fossil vertebrates as old as the Upper Cretaceous, suggesting that bone has served as a substrate for chiton feeding for more than 66 million years. Whether these bone modifications reflect algal grazing, carrion scavenging or bone consumption remains unsure, but the first hypothesis appears to be the most parsimonious, as well as the most likely in light of the available actualistic data. As the role of bioerosion in controlling fossilization can hardly be overestimated, further research investigating how grazing organisms contribute to the biostratinomic processes affecting bone promises to disclose new information on how some marine vertebrates manage to become fossils.

Just a different place to graze? An unusual occurrence of the echinoid feeding trace Gnathichnus pentax on a marine vertebrate coprolite (Miocene, Italy) and its palaeoethological implications

Faeces produced by marine vertebrates and macro-invertebrates contain sufficient organic matter to represent a usable food source for a wide array of macroscopic animals. In some extant marine environments, coprophagy even represents a crucial trophic interaction in food webs. In ancient ecosystems, coprophagy by macroscopic animals is occasionally exemplified by coprolites that exhibit biting traces or burrows. Here, we report Gnathichnus pentax on an exquisitely preserved vertebrate-bitten vertebrate coprolite from the marine calcareous deposits of the Pietra leccese (Miocene, southern Italy). This unusual occurrence is interpreted as evidence of the feeding activity of a regular echinoid; in particular, it may represent either exploratory coprophagy or the browsing of an algal (microbial) film that locally developed on the exterior of the faeces. Strengthening the former interpretation, the development of microbial communities on submerged faeces often leads to their destruction; furthermore, some extant Antarctic echinoderms are well known to ordinarily feed on vertebrate faeces, and coprophagy is believed to be fairly widespread among sea urchins. Supporting the algal browsing hypothesis, in turn, only a limited area of the external surface of the faeces was subject to grazing, and the resulting trace is neatly defined, which suggest that the feeding sea urchin targeted a precise location on the dung's exterior when the latter was already rather firm. To our knowledge, the G. pentax specimen studied here represents the first published record of this ichnotaxon on a coprolite.

Miocene Cupressinoxylon from Gökçeada (Imbros), Turkey with Protophytobia cambium mining and the study of ecological signals of wood anatomy.

The recognition of the Miocene Climate Optimum (MCO) in terrestrial palaeoenvironments of the Eastern Mediterranean is restricted to Lesbos and Lemnos Islands, Greece. This area is significant for its wood microfossils. A recently-discovered fossil wood assemblage from Gökçeada (Imbros) Island, Turkey, including tree species similar to the Greek findings, is thought to have an early Miocene age. Here, we revise the age of the latter plant fossiliferous locality, re-evaluate the area for the study of MCO for the terrestrial palaeoecosystems of the Eastern Mediterranean and the nomenclature errors referring to the occurrence of fossil wood. We present the plant-insect-environment interactions using detailed anatomical descriptions, of an extinct conifer and its extinct cambium miner feeding traces observed in its secondary xylem. Three thin sections were prepared with standard palaeoxylotomical techniques from a small section of the silicified wood; the sections were observed under a light microscope. The anatomy of the conifer and its damage patterns were compared with those of extant and fossil Cupressaceae and Agromyzidae, respectively. The common anatomical features of the studied wood specimen and Hesperocyparis macrocarpa (Hartw.) Bartel and a shared characteristic (the number of the cross-field pits - a feature we consider of diagnostic value) with Xanthocyparis vietnamensis Farjon & T.H. Nguyên led to its assignment to the Hesperocyparis-Xanthocyparis-Callitropsis clade. The detailed study of the wound scars and anatomical abnormalities, the anatomical-environmental associations, and structural-functional reactions follow the identification of the wood's anatomy sensu Carlquist providing decisive results. Based on the distinctive characteristics presented, we identify our macrofossil as Cupressinoxylon matromnense Grambast, a stem or an extinct lineage of the Hesperocyparis-Xanthocyparis vietnamensis-Callitropsis nootkatensis clade with feeding traces of the fossil cambium miner of the genus Protophytobia Süss (Diptera: Agromyzidae), and anatomical damage and reaction tissue on adventitious shoots. The use of Protopinaceae and Pinoxylon F. H. Knowlton from the eastern Mediterranean are re-evaluated and corrections are provided. The age of the studied plant fossiliferous locality in Gökçeada is revised as middle Miocene, allowing the proposal of an eastern Mediterranean MCO hotspot, including Lesbos, Lemnos, and Gökçeada (Imbros) Islands.

Rapid assessment of feeding traces enables detection of drivers of saproxylic insects across spatial scales

Knowledge of habitat requirements of saproxylic insects and their response to habitat changes is critical for assessing the ecological impacts of forest management. Several studies have demonstrated a positive relationship of tree-species richness, deadwood volume, or structural diversity with saproxylic species diversity, while the relationship with the abundance of potential pest species have often been negative. A better understanding of which factors drive saproxylic insects’ occurrence is therefore essential for deriving urgently needed thresholds for key habitat conditions. We tested a rapid assessment method applicable at large scale based on recorded feeding galleries and boreholes assessed during the Austrian National Forest Inventory to investigate the drivers and habitat thresholds of different saproxylic insect families; i.e. Buprestidae, Cerambycidae, Curculionidae, Siricidae, at multiple spatial scales; i.e. at the object, forest stand and landscape level. We modelled the relative abundance of all insects and these families considering nineteen explanatory variables using ordinal logistic regression models. Key habitat characteristics were identified using recursive partitioning. Our results revealed complex interactions among influencing factors at different spatial scales. We showed that deadwood volume was of surprisingly little importance. Instead, individual tree characteristics were of major importance, demonstrating the value of resource quality and variability. The abundance of all saproxylic insect families increased with advancing decomposition, on trees taller than 18 m, and above a living stand volume of 41 m3ha−1. Aiming to guide forest management, not only forest type-specific, but tree species-specific deadwood management is needed, taking into account site-specific conditions, including temperature and precipitation. For assessing temporal trends in insect colonization and habitat dynamics as well as the effects of forest management, we propose a continuous monitoring of insect traces, including living but weakened trees. This will allow for further thresholds that are urgently needed for maintaining biological diversity in forest ecosystems in the face of climate change.

Guts, gut contents, and feeding strategies of Ediacaran animals

The oldest animals appear in the fossil record among Ediacara biota communities. They prelude animal-dominated ecosystems of the Phanerozoic and may hold clues to the appearance of modern animal phyla in the Cambrian explosion. However, little is known about the phylogeny of the Ediacaran organisms and even less about their diet and feeding behavior.1,2,3 An exception is mollusc-like Kimberella, for which a fossilized gut, feeding traces, and even potential coprolites have been found.4,5 By contrast, Ediacaran organic-walled tubes, such as Sabellidites and Calyptrina, are thought to belong to tube worms comparable with modern Siboglinidae that have no gut but gain their nutrition from symbiotic bacteria.6,7 Here, we examine the gut contents of Ediacaran animals using biomarker molecules. We show that 558-million-year (Ma)-old tube worm-like Calyptrina and mollusc-like Kimberella possessed a gut and shared a diet of green algae and bacteria. Despite their ancient age, sterol metabolism within the gut of both organisms was already comparable to extant invertebrates.8Dickinsonia, one of the key Ediacaran animals, show no traces of dietary molecules, indicating a different feeding mode and possible external digestion analogous to modern Placozoa. Lipid biomarkers uncover a range of feeding strategies in Ediacaran communities, highlighting true eumetazoan physiology of some Ediacaran animals.

A gar-bitten vertebrate coprolite from the Neogene of the Atlantic Coastal Plain, USA, and a new ichnospecies of Machichnus Mikuláš et al., 2006

Vertebrate-bitten coprolites are seemingly rare; nonetheless, within the past dozen years, a handful of these composite trace fossils have been found and described. Here, we describe a single crocodile coprolite from the Lower Miocene Calvert Formation in New Kent County, Virginia, USA, showing bite marks. The size and morphology of the coprolite is consistent with a crocodilian origin. Seven parallel, gently curving gouges, of biogenic origin, disrupt the surface of the coprolite. As it is a medium preserving bite marks, this coprolite qualifies as a morderolite. Furthermore, because of the presence of larger/deeper primary, and finer secondary gouges, which we interpreted as individual tooth marks, the identity of the vertebrate that bit the coprolite is most likely gar (Lepisosteidae). Because other comparable coprolites preserving similar sets of primary and secondary gouges are known, this unique trace fossil is given a new ichnotaxonomic name, Machichnus dimorphodon isp. nov. Many more much smaller markings, interpreted as feeding traces by smaller organisms (possibly invertebrates) also ornament the surface of the coprolite.

Ichnology and Sedimentology of the Lower Cretaceous Wabiskaw Member (Clearwater Formation) Alberta, Canada

Identifying facies and paleoenvironmental interpretation of the rock record is complicated due to the interplay of independent variables (i.e. wave-, river- and tidal-input) in marginal- and shallow-marine environments. This study integrates sedimentology and ichnology to characterize the depositional environments of the Lower Cretaceous Wabiskaw Member. The deltaic and strand plain shoreface-offshore deposits of Wabiskaw Member of Clearwater Formation of northeast Alberta provide an excellent case study to evaluate the ichnological and sedimentological characteristics associated with laterally and vertically variable stresses in wave-influenced nearshore settings. The Wabiskaw Member is studied using four sedimentary facies associations (Ten sedimentary facies). Facies association 1(FA-1) consists of massive, sharp-based mudstones and lenticular sandstone with small-scale soft-sediment deformation features, syneresis cracks and small-scale oscillation ripples. The ichnological suite mainly includes small grazing and deposit-feeding traces, representing the Phycosiphon Ichnofacies. Facies association 1(FA-1) is interpreted to record deposition in a prodeltaic setting. Facies association 2 (FA-2) is fine-to-medium-grained sandstone and thin mudstone with current, oscillation and combined flow ripples. The low angle and trough cross-beds, soft-sediment deformation structure, mud chips and coal debris are common. The trace fossil suite includes sporadically distributed deposit-feeding traces belonging to the Rosselia Ichnofacies. This facies association is interpreted to be deposited in the delta front to a mouth bar setting. Facies association 3 (FA-3) is gray to bluish-gray mudstone with minor sandstone interbeds (massive, planar parallel to hummocky cross-stratified). FA-3 is moderate to highly bioturbated. The ichnodiversity and abundance is high with dominant horizontal and subordinate vertical traces, including the dominance of deposit and detritus feeding traces representing the archetypal Cruziana Ichnofacies ichnological suite. Facies association 3 (FA-3) is interpreted as being deposited in a storm-influenced offshore environment. Facies association 4 (FA-4) is upper fine to fine-grained glauconitic sandstone with minor mudstone interbeds at the base. Physical sedimentary structures including massive and planar (horizontal and low angle), hummocky, and swaley crossing-stratification. FA-4 is heavily burrowed with a diverse suite of horizontal and vertical traces of deposit and detritus-feeding structures, representing a proximal expression of Cruziana Ichnofacies. Facies association 4 (FA-4) represents distal lower to middle shoreface deposition. The Wabiskaw Member deltaic (prodelta-delta front) deposits, producing characteristic sedimentological-ichnological signatures, distinguishing these deposits from related strand plains. In addition to characteristic deltaic traits (e.g. soft-sediment deformation structures, fluid mud and syneresis cracks), these deposits commonly contain comparably stressed low-diversity and diminutive trace-fossil suites. On the other hand, fully marine strand plain shoreface-offshore complexes are characterized by comparably robust trace fossils with high ichno-diversity and bioturbation intensities.