Fish Teeth Research Articles

Freshwater exploitation at Ajvide - Pitted ware culture fishing practises investigated through laser ablation facilitated strontium isotope analyses

The importance of marine resources for the Neolithic hunter-fisher-gathers of the Pitted Ware Culture of Gotland, Sweden, is well documented through zooarchaeological analyses and diet studies of human remains. Terrestrial areas were important for living and supplementing the diet but the extent of the terrestrial territories and regions of land use for different groups is largely unknown. The presence of euryhaline species in recovered zooarchaeological assemblages indicates that freshwater fishing or fishing in the brackish estuaries of the Baltic Sea was part of the subsistence practises. To explore if the inland freshwaters of Gotland were used and, if exploited, where they were located, 18 teeth from euryhaline fish from the Pitted Ware Culture site Ajvide on Gotland were selected. The 87Sr/86Sr isotope ratios in the fish teeth were analysed using laser ablation-multi collector-inductively coupled plasma-mass spectrometry and correlated with an updated bioavailable baseline of Gotlandic water sources. Through this approach, the habitational origin of the fish was shown to primarily stem from at least six freshwater sources located in the west-central area of Gotland, in close relation to the site, with a few individuals originating from within the Baltic Sea. The study highlights the significance of ichthyoarchaeological analysis in understanding the territorial practice of past foraging societies and recommends further studies on euryhaline species to expand our knowledge of fish habitat, human resource utilization and land use.

Uptake time and enrichment mechanism of rare earth elements in deep-sea bioapatite

Bioapatite is widely recognized as the primary carrier for rare earth elements and yttrium (REY) in deep-sea REY-rich muds. The incorporation of REY into bioapatite occurs at the water-sediment interface, which has the potential to serve as a proxy for reconstructing paleoenvironmental conditions. The timing of REY uptake and the fractionation of rare earth elements (REEs) within bioapatite are crucial factors to understanding the application of these proxies. In this study, we present in-situ geochemical data for bioapatite obtained from surface sediments in the high sedimentation rate Somali Basin of the northwestern Indian Ocean (NWIO), as well as fish teeth within nodules from the low sedimentation rate in the northwestern Pacific Ocean (NWPO). Our findings indicate that the uptake time of REY occurred rapidly, with the ΣREY content reaching 7265 μg/g in bioapatite from the surface sediments in the NWIO within several thousand years. The bone fragments exhibited a high ΣREY content, which was primarily attributed to substitution processes. This led to a notably elevated proportion of middle rare earth elements (MREE) compared to fish teeth. In contrast, the adsorption and substitution mechanisms responsible for REY incorporation decreased from the root to the tip in fish teeth, resulting in a pronounced decline in ΣREY content. The adsorption mechanism was identified as the primary process responsible for REY uptake in the fish teeth within the studied nodules from the NWPO. The fractionation pattern of REEs in these teeth exhibited similarities to that of fish teeth from the NWIO. Therefore, we inferred that the fish teeth within the studied nodules may preserve the original information during late diagenesis. The variation of REY contents in the nodules was influenced by the redox environment, and there is no evidence to support the migration of REY from the nodules into the fish teeth.

Rare earth element enrichment process of bioapatite in deep-sea REY-rich sediments

Rare earth element and yttrium (REY) compositions of bioapatite (e.g., fish tooth and bone) can serve as potential paleoceanographic indicators. However, the REY enrichment of bioapatite and REY transfer from FeMn micronodule to bioapatite remain unclear owing to a lack of comparative study on these processes under variable redox conditions (oxic vs. suboxic), which hampers the utility of these indicators. To address these uncertainties, we conducted in situ geochemical analyses of fish teeth and FeMn micronodules from two REY-rich sediment cores (GC01 and GC02) collected from the Clarion–Clipperton fracture zone in the central equatorial Pacific. We found that the Ce/Ce* ratios of fish teeth from GC01 (sediments ΣREY = 723 ± 274 ppm) and GC02 (sediments ΣREY = 506 ± 65 ppm) gradually increased with depth under oxic conditions, with calculated oxic pore water-derived REY increasing from ∼0–3% on the surface to ∼11–24% at 200 cmbsf. In deep sediment columns (>200 cmbsf), the suboxic pore water contributed a small amount of REY (∼4% to ∼13%) to fish teeth, as evidenced by sharp increases in Ce/Ce* ratios of fish teeth and decreases in Ce/Ce* ratios and increases in YN/HoN ratios of micronodules. Therefore, the REY-patterns of fish teeth in core-deep samples were overprinted by oxic–suboxic pore waters may be unreliable archives of ancient bottom seawater.

Analysing Trophic Competition in †Otodus megalodon and Carcharodon carcharias through 2D-SEM Dental Microwear

The extinction of the massive apex predator †Otodus megalodon during the Pliocene is a subject of debate, with climate change and emergence of competitors as potential factors, such as Carcharodon carcharias. We explore trophic interactions of †O. megalodon and the C. carcharias by the analysis of dental microwear. For this purpose, high-resolution casts were made from ten megalodon teeth and six white shark teeth. Then, replicas were produced for examination using a Scanning Electron Microscope. Following a previous work on non-occlusal teeth of bony fishes, density and scratch length as well as mean vector were taken into account for the analysis. Our findings revealed that †O. megalodon shows a slight preference for less abrasive diets compared to C. carcharias. However, no significant differences were found in the dental microwear patterns of both species. These results provide additional evidence of a similar trophic spectrum between C. carchariasand †O. megalodon in the Mediterranean Sea basin, contrasting with previous data obtained through texture analysis. However, due to the inability to estimate sizes, we cannot rule out possible ontogenetic dietary differences. Therefore, future studies estimating sizes and incorporating data from other basins could provide more information.

Late Oligocene–Miocene evolution of deep-water circulation in the abyssal South China Sea: Insights from Nd isotopes of fossil fish teeth

Abstract A long-term neodymium isotope (εNd) record of fossil fish teeth was investigated to constrain the evolution of deep-water circulation in the abyssal South China Sea (SCS) during the late Oligocene–Miocene (27–10 Ma). Fish teeth samples were collected from the oceanic red beds at International Ocean Discovery Program Expedition 367 Site U1499 (water depth 3758 m). Seawater εNd values (from –7.1 to –4.8, average –6.1) prior to 15 Ma indicate that water masses in the abyssal SCS resulted from the mixing of more radiogenic Upper Circumpolar Deep Water (UCDW, average –4.5) and less radiogenic Lower Circumpolar Deep Water (LCDW, average –6.4). The general decrease in εNd values was attributed to an increasing influence of the unradiogenic LCDW at the studied site, consistent with the subsidence and the associated deepening of the SCS plain. After 15 Ma, seawater εNd dropped significantly to a range of –8.9 to –6.1 (average –7.5), indicating a slowdown in the hydrological connection between the deep-water masses in the SCS and the western Pacific Ocean. We argue that the formation of the Luzon Strait due to the uplift of the Luzon arc in the late Miocene led to the shallowing and narrowing of the SCS-Pacific channels. Consequently, penetration of LCDW was reduced and water masses in the abyssal SCS would have been less ventilated and strongly influenced by lithogenic input from the unradiogenic sediments of large Asian rivers draining the peri-Himalayan region.

The adsorption of cerium on synthetic δ-MnO2: Implications for Ce uptake behavior of hydrogenetic and early diagenetic ferromanganese nodules from the Western Pacific

Cerium (Ce) anomalies can be used to distinguish diagenetic and hydrogenetic nodules, making them an important discriminator for the genesis of marine ferromanganese nodules. To understand the enrichment and adsorption mechanisms of Ce in different types of ferromanganese nodules, we conducted mineralogical and geochemical studies on ferromanganese nodule layers formed through both hydrogenetic and early diagenetic processes as well as adsorption experiments on synthetic δ-MnO2 to monitor the Ce uptake during the different processes. The major and trace element contents of natural ferromanganese nodule layers were investigated by SEM, EPMA and LA-ICP-MS analysis. The marine nodule studied in this study consisted of a core of fish tooth and a rim that could be divided into the hydrogenetic (type I) and early diagenetic (type II) layers based on their mineralogy and Mn/Fe ratios. The Mn oxide mineral assemblage is composed of todorokite, buserite, birnessite, and vernadite (δ-MnO2) and occurred in both type I and II layers. The type I layer has laminated structures with a low Mn/Fe ratio (1.1–3.2; averaging at 1.7), and low Cu, Ni and Mg contents consistent with a hydrogenetic genesis. The type II layer has a columnar and stromatolitic structure with a high Mn/Fe ratio (5.1–54.0; averaging at 23.3) and high Cu, Ni and Mg contents that are similar to early diagenetic nodules. The ΣREE contents in type I and type II layers are 1405–3506 ppm (averaging at 2091 ppm) and 199–1232 ppm (averaging at 674 ppm), respectively, indicating that the REE is enriched in the hydrogenetic type I layers. Strong positive Ce anomalies are present type I layers ranging from 1.2 to 2.5 (averaging 1.9), but only slightly positive are seen in type II ranging from 0.4 to 2.4 (averaging at 1.0). Synthetic experiments to monitor the Ce uptake process show that Ce can be adsorbed onto δ-MnO2 with the XRD and FTIR patterns suggesting that the structure of δ-MnO2 did not change significantly, consistent with Ce behavior in hydrogenetic nodules. The results suggest that Ce is predominantly concentrated in hydrogenetic nodules in an oxic environment, whereas in the early diagenetic layer, there is less oxidation and fixation of Ce due to the suboxic conditions. Our findings are consistent with Ce anomalies in marine Fe-Mn nodules being the result of Mn oxide oxidation adsorption and then fixation (oxidation) after adsorption.

Early ray‐finned herbivores: the dental system of Eurynotoidiidae (Actinopterygii; middle–late Permian, European Russia) and implications for palaeobiology and palaeoecology

AbstractEurynotoidiformes are a little‐known group of actinopterygian fishes from the Permian of European Russia, characterized by the possession of multicuspid marginal teeth arranged in a single row. Morphologically, the teeth resemble those of Recent Cichlidae, Acanthuridae, Siganidae or Serrasalmidae, suggesting similar trophic adaptations related to herbivory. Tooth histology is similar to the majority of basal actinopterygians (composed of dentine, acrodin and collar enamel). Teeth are ankylosed in their attachment, and labial pleurodont in implantation, strengthening the tooth. The multicuspid tooth crowns derive from conical teeth of predatory or omnivorous ancestors, analogous to the evolution of multicuspid teeth in cichlid fishes. Tooth replacement in eurynotoidiforms is most comparable to an alternating pattern, with a possible simultaneous, unilateral replacement occurring in the whole jaw, similar to characiform fishes. Replacement teeth were formed extraosseously. Teeth of the inner dental arcade were conical. Based on comparisons with the teeth of extant actinopterygians specialized for herbivory, along with functional morphological analysis and consideration of wear patterns, we hypothesize that eurynotoidiforms represent the oldest known actinopterygians specialized for herbivory. Several strategies of herbivory in Recent actinopterygians were already realized by eurynotoidiforms as early as the Late Palaeozoic (middle and late Permian): grazing/cutting filamentous algae (Lapkosubia spp., Isadia suchonensis), browsing/biting off macrophyte fragments (Isadia aristoviensis), scraping/harvesting periphyton from hard substrates (Isadia opokiensis, I. arefievi). However, notable morphological differences in the jaws (elongate) and tooth arrangement (homodont along the jaw, functional teeth separated) suggest that this Permian experiment in herbivory followed different pathways compared to extant taxa.

Taphonomy of the middle Miocene regular echinoid spines from Cairo-Suez District, Egypt: Palaeoecological and palaeoenvironmental interpretations

The palaeoecology and palaeoenvironment of a dense cluster of regular echinoid spines that occur in an oyster-rich limestone layer are interpreted based on detailed taphonomic study. The paucispecific macrobenthic assemblage associated with these echinoid spines have been studied in the middle Miocene Geniefa Formation, Gebel Gharra, Cairo-Suez District of Egypt. Both echinoid spines and macrobenthic assemblages are dominated by moderately to well-preserved, moderately packed, highly disarticulated, moderately to poorly sorted, re-oriented, and moderately to highly fragmented specimens, confirming parautochthonous nature of this assemblage. The spines are commonly encrusted and bored. At least four taxonomic groups of encrusters are identified, including juvenile oysters, sheet-like cheilostome bryozoans, serpulids, and balanoid barnacles. The diversity of bioerosional ichnotaxa is moderate and includes Gastrochaenolites, Entobia, Maeandropolydora, Trypanites, and Spirolites. Moreover, some echinoid spines display distinct biting traces of fish, representing the first recorded of fish tooth bite marks on remains of regular echinoid spines from the Miocene deposits of Egypt. The faunal composition and trophic structure of the studied faunal assemblage indicate fully oxygenated and euhaline shallow-marine environment with meso- to eutrophic productivity level. The controlling environmental parameters include substrate consistency, bathymetry, water energy, surface-water productivity, and rate of sedimentation. Furthermore, two scenarios for sclerobionts colonisation and development of fish bite marks have been proposed. In the first syn vivo scenario, predatory fish either focused on the encrusting organisms attached to the spines or attacked the echinoid as a food source, resulting in the separation of spines from their original test during the echinoid’s life. In the second post-mortem scenario, disarticulated spines serve as a hard substrate for the colonisation of sclerobionts. Once again, the spines became subject to attacks by fish that fed on the encrusters, resulting in additional bite marks.

Testing alternative hypotheses for the decline of cichlid fish in Lake Victoria using fish tooth time series from sediment cores.

Lake Victoria is well known for its high diversity of endemic fish species and provides livelihoods for millions of people. The lake garnered widespread attention during the twentieth century as major environmental and ecological changes modified the fish community with the extinction of approximately 40% of endemic cichlid species by the 1980s. Suggested causal factors include anthropogenic eutrophication, fishing, and introduced non-native species but their relative importance remains unresolved, partly because monitoring data started in the 1970s when changes were already underway. Here, for the first time, we reconstruct two time series, covering the last approximately 200 years, of fish assemblage using fish teeth preserved in lake sediments. Two sediment cores from the Mwanza Gulf of Lake Victoria, were subsampled continuously at an intra-decadal resolution, and teeth were identified to major taxa: Cyprinoidea, Haplochromini, Mochokidae and Oreochromini. None of the fossils could be confidently assigned to non-native Nile perch. Our data show significant decreases in haplochromine and oreochromine cichlid fish abundances that began long before the arrival of Nile perch. Cyprinoids, on the other hand, have generally been increasing. Our study is the first to reconstruct a time series of any fish assemblage in Lake Victoria extending deeper back in time than the past 50 years, helping shed light on the processes underlying Lake Victoria's biodiversity loss.

An 800-year record of benthic foraminifer images and 2D morphometrics from the Santa Barbara Basin

The Santa Barbara Basin is an extraordinary archive of environmental and ecological change, where varved sediments preserve microfossils that provide an annual to decadal record of the dynamics of surrounding ecosystems. Of the microfossils preserved in these sediments, benthic foraminifera are the most abundant seafloor-dwelling organisms. While they have been extensively utilized for geochemical and paleoceanographic work, studies of their morphology are lacking. Here we use a high-throughput imaging method (AutoMorph) designed to extract 2D data from photographic images of fossils to produce a large image and 2D shape dataset of recent benthic foraminifera from two core records sampled from the center of the Santa Barbara Basin that span an ~800-year-long interval during the Common Era (1249–2008 CE). Information on more than 36,000 objects is included, of which more than 22,000 are complete or partially-damaged benthic foraminifera. The dataset also includes other biogenic microfossils including ostracods, pteropods, diatoms, radiolarians, fish teeth, and shark dermal denticles. We describe our sample preparation, imaging, and identification techniques, and outline potential data uses.

Focused ion beam-SEM 3D study of osteodentin in the teeth of the Atlantic wolfish Anarhichas lupus

The palette of mineralized tissues in fish is wide, and this is particularly apparent in fish dentin. While the teeth of all vertebrates except fish contain a single dentinal tissue type, called orthodentin, dentin in the teeth of fish can be one of several different tissue types. The most common dentin type in fish is orthodentin. Orthodentin is characterized by several key structural features that are fundamentally different from those of bone and from those of osteodentin. Osteodentin, the second-most common dentin type in fish (based on the tiny fraction of fish species out of ∼30,000 extant fish species in which tooth structure was so far studied), is found in most Selachians (sharks and rays) as well as in several teleost species, and is structurally different from orthodentin.Here we examine the hypothesis that osteodentin is similar to anosteocytic bone tissue in terms of its micro- and nano-structure. We use Focused Ion Beam-Scanning Electron Microscopy (FIB/SEM), as well as several other high-resolution imaging techniques, to characterize the 3D architecture of the three main components of osteodentin (denteons, inter-denteonal matrix, and the transition zone between them). We show that the matrix of osteodentin, although acellular, is extremely similar to mammalian osteonal bone matrix, both in general morphology and in the three-dimensional nano-arrangement of its mineralized collagen fibrils. We also document the presence of a complex network of nano-channels, similar to such networks recently described in bone. Finally, we document the presence of strings of hyper-mineralized small ‘pearls’ which surround the denteonal canals, and characterize their structure.

Applicability of Object Detection to Microfossil Research: Implications From Deep Learning Models to Detect Microfossil Fish Teeth and Denticles Using YOLO‐v7

AbstractMicrofossils of fish teeth and denticles, referred to as ichthyoliths, provide critical information for depositional ages, paleo‐environments, and marine ecosystems, especially in pelagic realms. However, owing to their small size and rarity, it is time‐consuming and difficult to analyze large numbers of ichthyoliths from sediment samples, limiting their use in scientific studies. Here, we propose a method to automatically detect ichthyoliths from microscopic images using a deep learning technique. We applied YOLO‐v7, one of the latest object detection architectures, and trained several models under different conditions. The model trained under appropriate conditions with an original data set achieved an F1 score of 0.87. We then enhanced the data set efficiently using the pre‐trained model. We validated the practical applicability of the model by comparing the number of ichthyoliths detected by the model with those counted manually. This revealed that the best model can predict the number of triangular teeth, denticles and irregularly shaped teeth with minimal human intervention. This object detection method can extend the applicability of deep learning to a wider array of microfossils and has the potential to dramatically increase the spatiotemporal resolution of ichthyolith records for applications across disciplines.

Migration and exchange of rare earth elements between phosphate and iron manganese phase: A case study from fish tooth-bearing nodules

Deep-sea sediments that are widely distributed in the Pacific Ocean could be an important future resource for rare earth element (REE) and yttrium (REY) due to their high concentrations of REY. Bioapatite fossils as well as Fe-Mn (oxyhydr) oxides (e.g., micronodules) are recognized as significant carriers of REY in deep-sea sediments. Notably, bioapatite fossils, account for more than 60% of the total REY content in bulk sediments, underscoring their significance as primary host for REY. However, the mechanisms of REY enrichments, variations in Ce anomalies, and REY substitution in bioapatite fossils remain under explained. In this study, we performed detailed in situ geochemical, isotope geochemical and chemical imaging analyses on fish tooth-bearing nodules.Our results indicate that fish teeth are mainly composed of Ca, P, F and Na, which accounting for over 95 % of the total composition of these teeth. On the one hand, the concentrations of Ca, P and F exhibit strong positive correlations with each other: their contents increase from the inside to the outside of the dentine shell. On the other hand, Na concentration display a different trend that the highest concentration is found in the center part of shark teeth. Despite the theoretical nearly absence of seawater as potential transport media, REYs migrated from the ferromanganese oxides phase to phosphate phase, and their contents decreased from inside layers to outside layers of dentine. During the long-term substitution processes in geological time, a portion of Ce3+ would be oxidized into immobile Ce4+ under oxic conditions, resulting in less incorporation of Ce3+ into the outer layers of dentine compared to other REY3+. As a consequence, stronger negative Ce anomalies were observed in the inside layers than in outside layers of dentine. The laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) mapping together with the in-situ geochemistry results indicate the negligible participation of Si in REY substitution, whereas Na exhibits a pronounced preference for substituting Ca2+ with REY3+. Therefore, we propose the following substitution scheme for incorporating REY into the crystal lattice of fish teeth: REY3+ + Na+↔ 2Ca2+. Our study clarified the fraction of REY during their migration from the Fe-Mn phase to the phosphate phase, and also contributes to a deeper understanding of the REY enrichment mechanism in pelagic sediments.

Taphonomic analysis of microfossil bonebeds from Western Gondwana: a case study from the late Permian Corumbataí Formation (Paraná Basin, Brazil)

ABSTRACT Storm deposits are common in geological records and encompass a variety of fossil assemblages affected by taphonomic processes that can biased fossil preservation. Here, we describe a microfossil bonebed to demonstrate the role played by certain filters in the final composition of storm-generated fossil accumulations. These layers are recurrent in the Paraná Basin and possibly in other localities of Gondwana, outcropping over 1000 km in the Permian units of the basin. Thirty samples were systematically collected from the state of São Paulo and their components were analysed. These samples consisted of clay matrix, coprolites, scales, and teeth of lower actinopterygian (Palaeonisciformes) and Xenacanthiformes fish. The taphonomic signatures demonstrated that the layer formed as a lag deposit in a distal aquatic environment. Two major taphonomic filters were recognised. The first filter selected bioclasts according to size and density, whereas the second filter preserved only the original phosphatic elements. The third and minor filter were related to breakage, which occured during reworking and diagenesis, respectively. All of these processes contributed to the generation of an assemblage with limited composition and species richness. Thus, distal tempestites might not be useful for estimating palaeodiversity, but may still offer some valuable information about intraspecies variation.

3D relationship between hierarchical canal network and gradient mineralization of shark tooth osteodentin.

Osteodentin is a dominant mineralized collagenous tissue in the teeth of many fishes, with structural and histological characteristics resembling those of bone. Osteodentin, like bone, comprises osteons as basic structural building blocks, however, it lacks the osteocytes and the lacuno-canalicular network (LCN), which are known to play critical roles in controlling the mineralization of the collagenous matrix in bone. Although numerous vascular canals exist in osteodentin, their role in tooth maturation and the matrix mineralization process remain poorly understood. Here, high resolution micro-computed tomography (micro-CT) and focused ion beam-scanning electron microscopy (FIB-SEM) were used to obtain 3D structural information of osteodentin in shark teeth at multiple scales. We observed a complex 3D network of primary canals with a diameter ranging from ∼10 µm to ∼120 µm, where the canals are surrounded by osteon-like concentric layers of lamella, with 'interosteonal' tissue intervening between neighboring osteons. In addition, numerous hierarchically branched secondary canals extended out radially from the primary canals into the interosteonal tissue, with a decreasing diameter from ∼10 µm to hundreds of nanometers. Interestingly, the mineralization degree increases from the periphery of primary canals to the interosteonal tissue, suggesting that mineralization begins in the interosteonal tissue. Correspondingly, the hardness and elastic modulus of the interosteonal tissue is higher than those of the osteonal tissue. These results demonstrate that the 3D hierarchical canal network is positioned to play a critical role in controlling the gradient mineralization of osteodentin, also providing valuable insight into the formation of mineralized collagenous tissue without osteocytes and LCN. STATEMENT OF SIGNIFICANCE: : Bone is a composite material with versatile mechanical properties. Osteocytes and lacuno-canalicular network (LCN) are kown to play critical roles during formation of human bone. However, the skeleton of many fishes, including bone and osteodentin, although lacking osteocytes and LCN, could exhibit similar osteon-like structure and mechanical functions. Here, using various high resolution 3D characterization techniques, we reveal that the 3D network of primary canals and numerous hierarchically branched secondary canals correlate with the mineralization gradient and micromechanical properties of osteonal and interosteonal tissues of shark tooth osteodentin. This work significantly improves our understanding of the construction of bone-like mineralized tissue without osteocytes and LCN, and provides inspirations for the fabrication of functional materials with hierarchical structure.

A marine microvertebrate fauna from a temporary exposure of the Atherfield Clay Formation, Reigate, Surrey

A temporary exposure of the nearshore marine Atherfield Clay (Lower Greensand Formation, Aptian, Early Cretaceous) in the Reigate area (Wonham Mill) of Surrey was sampled for microvertebrate remains in Autumn 2013. Samples amounting to 858 kg of sediment were washed, dried, and sieved to 0.325 mm and the residue searched for all fossil content. This is the first definitive study of the Atherfield Clay chondrichthyan fauna of Surrey. The samples yielded teeth of hybodont sharks (Planohybodus ensis, Lonchidion breve), neoselachian sharks (Heterodontus sulcatus, Cretascyllium hassei, Protospinax sp., Protolamna sokolovi, Lamnid indet., Scyliorhinus muelleri, Scyliorhinus gen. et sp. indet., Protoscyliorhinus sp.) and batoids (Belemnobatis picteti, Squatirhina sp.). The neoselachian sharks and rays all constitute the first confident records for the various genera in the Atherfield Clay of the United Kingdom. Dermal denticles and bony fish teeth are also present in the samples, which also yielded small numbers of invertebrates (ammonite and crustacean), microcoprolites (Tomaculopsis tomaculopsis) and plant remains (fern indusia). The state of preservation of the chondrichthyan material suggests that none of the specimens are derived from older strata; the fauna is indigenous. The Surrey Atherfield Clay fauna is distinct from that recorded from the Atherfield Bone Bed on the Isle of Wight and the roughly coeval boreal fauna of the Speeton Clay.

A new composite fabricated from hydroxyapatite, gelatin-MgO microparticles, and compatibilized poly(butylene succinate) with osteogenic functionality

In this study, thermally processed recycled fish teeth (FT) and fish scales, magnesium oxide (MgO), and biobased polyesters were fabricated into new bioactive and environmentally friendly composites. The magnesium oxide was encapsulated into laboratory-made fish scale-derived gelatin to form gelatin-MgO microparticles. Hydroxyapatite (HA) and gelatin were obtained by heat-treating FTs and fish scales, respectively. Compatibilized poly(butylene succinate) (CPBS), i.e., poly(butylene succinate) (PBS) to which had been added acrylic acid-grafted PBS (PBS-g-AA) compatibilizer, was combined with HA/gelatin-MgO (GHA) to form CPBS/GHA composites. The structure and tensile properties of the composites were investigated. The CPBS/GHA composites improved the adhesion and proliferation of osteoblast cells. Osteoblast growth, osteoclast growth inhibition, and the antibacterial effect of CPBS/GHA composites were primarily due to the slow release of magnesium ions into the environment from the gelatin-MgO microparticles. Higher levels of calcium and phosphorus species were observed for various PBS/HA and CPBS/GHA composites immersed in simulated body fluid. Mineralization measurements indicated that calcium and phosphate ions precipitated in osteoblasts placed on PBS/HA and CPBS/GHA composites. The study successfully developed a new composite material containing 5 wt% gelatin/MgO (phr), CPBS/HA 10 wt% and 1.0 % gelatin/MgO (an optimum formula of MgO). This composite exhibited superior tensile strength, antibacterial effect, osteoclast growth enhancement, and osteoclast growth reduction. These results suggest that the composites may facilitate the formation of new bone formation in vivo. The CPBS/GHA composites displayed good bone tissue repair ability in engineering applications.

A climate perturbation at the Middle –Late Jurassic Transition? Evaluating the isotopic evidence from south-central England

The Jurassic greenhouse is punctuated by short cooling intervals. Some published oxygen isotope records of belemnite rostra and fish teeth have been interpreted to reveal a prominent decrease in seawater temperature during the Late Callovian–Early Oxfordian. This is in part the basis for a proposed an ice age at the Middle-Late Jurassic Transition. In contrast relatively constant oxygen isotope records and therefore seawater temperatures as well as carbon isotope values characterized by significant scatter but showing more positive values during the middle and late Callovian have been reported from elsewhere. This research has constructed a stable isotope stratigraphy (from belemnites, Gryphaea and oysters) principally from the Callovian-Oxfordian interval (from southern England) and integrated these data with existing data to assess the pattern of carbon and oxygen isotopic change. Our marine macrofossil record reveals isotopic patterns that are generally comparable with other European basins. Carbon isotopic trends are consistent with bulk carbonate carbon isotope records displaying systematic fluctuations, the largest of which (Middle Callovian, Calloviense/Jason Zones to Early Oxfordian, Mariae Zone) corresponds to previously identified phases of environmental perturbation. Such a trend may have resulted from enhanced burial and preservation of organic matter, leaving the seawater enriched in the heavy carbon isotope. Inferred cooling, derived from our oxygen isotope data from southern England, occurs within the Late Callovian and the Early Oxfordian (Athleta to Mariae zones). Cooling post-dates this positive carbon isotope excursion. Enhanced carbon burial and atmospheric carbon dioxide draw down may have induced cooling. In this study the analysis of a single region (southern England) allows critical factors controlling the oxygen isotopic composition of the carbonates (e.g. temperature and the oxygen isotopic composition of the solution from which the carbonates precipitated) to be more comparable. If Jurassic polar climates were truly warm such a degree of cooling would undoubtedly lead to cooler polar temperatures – but only with seasonal ice.

Early diagenetic REE migration from Fe-Mn nodules to fish teeth in deep sea sediments

In deep sea sediments, rare earth elements and yttrium (REYs) are predominantly carried by bioapatite and Fe-Mn (oxyhydr)oxides. According to recent studies, REYs can migrate into bioapatite after the dissolution of Fe-Mn (oxyhydr)oxides. However, the REY migration mechanism from Fe-Mn (oxyhydr)oxides to bioapatite are still unclear. Here, we integrated in situ trace element and Nd isotope analyses to elucidate the geochemical characteristics of fish tooth-bearing Fe-Mn nodules from the Northwest Pacific Ocean. Our Fe-Mn nodule samples can be classified into different morphological and geochemical types of the different periods in early diagenesis: (I) completely overgrown around bioapatite; II) overgrown around half of the bioapatite. Type I nodules grow around a bioapatite core, which has high LaN/SmN (0.41–0.50, avg. 0.46) and LaN/YbN (0.49–0.90, avg. 0.62). The ΣREY content is non-uniform in the two bioapatite types (WP-01 & WP-02) in Type I nodules, i.e., 475–2150 ppm and 272–431 ppm, respectively. The REY results show that the bioapatite is mainly adsorbed REY in early diagenesis. Type II nodules were covered both inside and at the tip of the tooth. The LaN/SmN (0.34–0.38, avg. 0.36) and LaN/YbN (0.26–0.61, avg. 0.37) ratios of the bioapatite samples are relatively low. Meanwhile, the ΣREY content is very uneven (229–3521 ppm). The REY data show that the bioapatite is mainly substituted during strong early diagenesis. The intercrystalline pores in some authigenic apatite may have closed upon recrystallization, causing REY redistribution and fractionation. The Y/Ho vs. ΣREE/Th plot shows a higher REY proportion from pore water in type II nodules than in type I ones. The widespread distribution of high Mn content and the gradual decrease of REY content from the nodule rim to core reflect the transport of REY from dissolved Fe-Mn (oxyhydr)oxides to bioapatite during early diagenesis under suboxic conditions. From type I to type II nodules, the mean εNd value of bioapatite increases from −6.69 to −5.56. The comparison of εNd values between REY-rich mud and bioapatite indicate that the REYs were derived from the bottom water and pore water in deep sea sediments. Our findings comprehensively document the transport and enrichment mechanisms of REY in early diagenetic processes from Fe-Mn (oxyhydr)oxides to bioapatite, which we argued to be relatively localized.

In situ Strontium isotope stratigraphy of fish teeth in deep-sea sediments from the western Clarion-Clipperton Fracture Zone, eastern Pacific Ocean

The geochronology of deep-sea sediments beneath the carbonate compensation depth (CCD) presents a challenge due to the calcareous microfossils dissolution, low sedimentation rates, sedimentary hiatus, and redeposition. Fish teeth, commonly found in deep-sea sediments, have been utilized for Sr isotope stratigraphic dating. However, continuous Sr isotope exchange with pore water limits the utility of fish teeth in this context.In this study, we employed laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS), scanning electron microscopy (SEM), and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to obtain accurate stratigraphic chronology results from rare earth element and yttrium (REY)-rich sediments in the Clarion-Clipperton Fracture Zone (CCFZ) of the Pacific Ocean.Our analysis indicated that a fish tooth characterized by a dense structure and low La content exhibited a relatively initial 87Sr/86Sr ratio. Additionally, La contents at the same depth displayed a strong positive correlation with 87Sr/86Sr ratios, suggesting that Sr isotopes exchange with pore water during early diagenesis when La and other elements entered the fish teeth. However, certain fish teeth were able to resist early diagenesis alteration due to their dense structure.Based on in situ Sr-isotope stratigraphy results, we estimated the REY-rich layer age in core GC1901 to be 24–32 Ma, consistent with the REY-rich layers of DSDP/ODP in the CCFZ. Our study thus provides a new method for in situ Sr isotope analysis of fish teeth, which improves the accuracy of Sr isotope stratigraphy of pelagic sediments and could be widely used in deep-sea exploration.