Age-Related Patterns of Traumatic Facial Fractures in the Appalachian Tri-state Area: A Five-Year Retrospective Study.

Introduction Traumatic facial injuries, leading to facial fractures represent a significant subset of traumatic events, with age emerging as a crucial determinant influencing both their etiology and outcomes. Understanding the age-related patterns of traumatic facial fractures is essential for developing targeted prevention and management strategies. In this context, the Appalachian tri-state area stands as an underexplored region concerning this issue, necessitating comprehensive research to elucidate the nuances of age-related traumatic facial fractures within this geographic context. Methods This retrospective study delves into the age-related patterns of traumatic facial fractures within the Appalachian tri-state area, drawing upon patient records from Cabell Huntington Hospital and Saint Mary's Medical Center spanning a five-year period. The study cohort encompasses 623 patients categorized into three age groups: individuals aged <22 years, those aged 22-65 years, and individuals over 65 years. Data analysis involves meticulous examination of mechanisms of injury, injury severity scores (ISSs), hospital length of stay, and the prevalence of surgical interventions across different age cohorts. Results Out of 623 patients, 104 (16.7%) were under 22 years old, 367 (58.9%) were between 22 and 65 years old, and 152 (24.4%) were over 65 years old. The majority were male (70%). Falls were the most common cause of facial fractures in patients over 65 (78%), while assaults were predominant in the 22-65 age group (24%), and motor vehicle collisions (MCVs) in those under 22 (34%). The median ISS and hospital stay durations were similar across age groups. 28% of patients underwent surgery, with significant variation among age groups (p<0.001): 38% for <22 years, 33% for 22-65 years, and 11% for >65 years. Mandibular fractures were more prevalent in younger patients, with rates of 12% for <22 years compared to 5.3% for >65 years. Logistic regression analysis revealed that patients aged 22-65 had 4.10 times higher odds (95% CI=2.38, 7.45, p<0.001) of undergoing surgery, while those under 22 had 5.14 times higher odds (95% CI=2.73, 10.0, p<0.001) compared to those over 65. Significant associations were found for mandibular and bilateral mandibular outcomes in patients aged 22-65 years. Discussion These findings underscore the imperative for tailored prevention strategies and age-specific treatment protocols to optimize patient outcomes. Fall prevention initiatives for the elderly and interventions addressing sports-related injuries for younger individuals are paramount. Moreover, the study highlights the necessity of specialized care protocols for elderly patients to minimize hospital stay durations and manage age-related comorbidities effectively. Moving forward, further research should address limitations, validate findings, and explore the efficacy of specific interventions, thereby paving the way for enhanced preventive measures and management strategies tailored to the diverse age cohorts affected by traumatic facial fractures in the Appalachian region.

A Comparative American Board of Surgery In-Training Examination (ABSITE) Performance Analysis Between International vs. Domestic Graduates and Doctor of Medicine (MD) vs. Doctor of Osteopathic Medicine (DO) Medical Degrees.

Introduction The American Board of Surgery (ABS) plays a pivotal role in certifying surgeons in the United States, with the American Board of Surgery In-Training Examination (ABSITE) serving as a critical assessment tool for general surgery residents aspiring for certification. The aim of this study is to compare the performance of international medical graduates (IMGs) to their domestic counterparts and assess the impact of different medical degrees on ABSITE scores. Notably, ABSITE scores often dictate the trajectory of a surgical career, including opportunities for fellowship placements in specialized fields such as plastic surgery. Methods This study focused on general surgery residents enrolled at Marshall University from 2014 to 2022. Data encompassing ABSITE scores, TrueLearn quiz percentages, and TrueLearn mock exam results were collected for analysis. Descriptive statistics summarized sample characteristics, and linear mixed models were employed to address correlations. Statistical analyses were conducted using the Statistical Analysis System (SAS) (version 9.4; SAS Institute Inc., Cary, NC, USA), with significance defined by a two-sided test with p < 0.05. Results Among the 48 participants, comprising 24 non-international medical graduates (nIMGs) and 24 IMGs, IMGs demonstrated superior performance across various metrics. They exhibited higher quiz percentages (67% vs. 61%; p = 0.0029), mock Exam 1 scores (64% vs. 58%; p = 0.0021), mock Exam 2 scores (66% vs. 58%; p = 0.0015), ABSITE scores (560 vs. 505; p = 0.010), and ABSITE percentages (74% vs. 68%; p = 0.0077) compared to nIMGs. Analysis between Doctor of Osteopathic Medicine (DO) and Doctor of Medicine (MD) participants revealed no statistically significant differences in performance metrics, highlighting the comparability of these medical degrees in the context of ABSITE scores and related assessments. Discussion/conclusion This study underscores the superior performance of IMGs over nIMGs in ABSITE examinations, shedding light on the critical role of ABSITE scores in shaping surgical careers. Higher scores correlate with enhanced opportunities for coveted fellowship placements, particularly in specialized fields like plastic surgery. Understanding these dynamics is crucial for resident training and navigating the competitive landscape of surgical sub-specialization. Future research endeavors can delve deeper into the factors influencing ABSITE performance, thereby facilitating the development of targeted interventions to support residents in achieving their career aspirations.

Breast Augmentation Patient Satisfaction in an Appalachian Region.

The prevalence of cosmetic plastic surgeries, including breast augmentation, has risen significantly, with breast augmentation being among the most sought-after procedures. However, there's a dearth of research on patient outcomes and satisfaction, particularly in rural areas like the Appalachian region. This retrospective study aimed to fill this gap by examining patient satisfaction and complications following breast augmentation surgery among rural Appalachian patients in the tri-state (West Virginia, Kentucky, and Ohio) area. A total of 63 patients who underwent primary breast augmentation at a regional referral center from June 2014 to December 2022 were included in the study. Patient records were reviewed and data on demographics, complications, re-operations, and satisfaction scores were analyzed. Results revealed no significant differences between rural and urban populations in terms of demographic characteristics, complication rates, re-operation rates, or satisfaction scores. Logistic regression models confirmed that rural/urban status did not significantly influence the likelihood of complications, re-operations, or satisfaction. Despite the study's limitations, including a small sample size and single-center design, the results indicate that rural Appalachian patients receive surgical care comparable to their urban counterparts and experience similar benefits from breast augmentation surgery. Recognizing the distinctive healthcare needs and obstacles faced by rural communities is essential for mitigating healthcare disparities and enhancing overall health outcomes. Future research and healthcare initiatives should prioritize improving access to care, fostering patient-centered approaches, and addressing systemic challenges in healthcare delivery across rural Appalachia.

Navigating the American Board of Surgery In-Training Examination (ABSITE) Success: Insights From Pre-assessment Practices in Preparing Surgical Residents for Competitive Sub-specialties.

Introduction The American Board of Surgery In-Training Examination (ABSITE) is a critical tool in assessing surgical residents' readiness for board certification and clinical practice. While various factors influencing ABSITE performance have been examined, the impact of innovative educational resources, such as TrueLearn, remains underexplored. TrueLearn's adaptive learning algorithms and comprehensive question banks offer a promising adjunct to traditional study methods. This study investigates the relationship between TrueLearn utilization and ABSITE performance among general surgery residents. Methods This retrospective study, ethically approved by the Marshall University Institutional Review Board (IRB No. 2097669-1), analyzed the performance of general surgery residents at Marshall University from 2014 to 2022. Data were collected on ABSITE scores. Additionally, quiz percentages (Quiz %) and scores from two mock exams (Exam 1 and Exam 2), all provided by the TrueLearn platform, were included in the analysis. Descriptive statistics summarized the sample characteristics. Linear mixed models were employed to examine the associations between TrueLearn engagement and ABSITE performance, accounting for the correlated nature of the data and addressing any missing data at random. Statistical analyses were conducted using the Statistical Analysis System (SAS, version 9.4; SAS Institute Inc., Cary, NC), with significance defined as a p-value < 0.05. Results The study cohort included 58 residents from 2016 to 2022. Linear mixed model analysis revealed significant positive correlations between TrueLearn Quiz %, Exam 1 scores, and Exam 2 scores with ABSITE performance. A 1% increase in Quiz % was associated with a 0.77-point rise in ABSITE scores (95% CI: 0.65, 0.89; p < 0.0001). For Exam 1, each point increase corresponded to a 6.36-point increase in ABSITE scores (95% CI: 5.01, 7.7; p < 0.0001), while Exam 2 scores showed a 3.8-point increase per point (95% CI: 2.74, 4.86; p < 0.0001). Discussion and conclusion Our findings underscore the significant impact of TrueLearn engagement on ABSITE performance, with higher quiz percentages and mock exam scores predictive of better ABSITE outcomes. This suggests that regular use of TrueLearn's educational resources enhances residents' knowledge and exam readiness. These results advocate for the integration of innovative educational tools such as TrueLearn into surgical training programs to optimize study strategies and improve exam performance. However, the study's retrospective design and single-institution focus limit the generalizability of the findings. Future research should explore these relationships in diverse settings and specialties and consider additional factors influencing ABSITE performance. This study highlights the positive association between TrueLearn utilization and ABSITE performance among general surgery residents, emphasizing the importance of innovative educational resources in surgical training. By enhancing engagement with platforms such as TrueLearn, surgical programs can improve residents' readiness for high-stakes examinations, ultimately contributing to the development of proficient surgical practitioners.

Burn Mortality in an Appalachian Referral Center: An Examination of Mortality Prediction Scores in a 13-Year Retrospective Study.

Introduction Burn injuries have profound implications, prompting the use of various mortality scoring systems. This study aimed to evaluate their effectiveness within our Appalachian burn referral center, which serves as the sole burn center in the state of West Virginia. Given this unique status, understanding the efficacy of mortality scoring systems within our center is crucial for resource allocation and optimizing patient outcomes in our region. Methods A retrospective analysis of patients admitted to Cabell Huntington Hospital Burn Intensive Care Unit (BICU) from January 2010 to June 2023 was conducted, assessing Baux (B), revised Baux (rB), Belgian Outcome in Burn Injury (BOBI), and Abbreviated Burn Severity Index (ABSI) scores. Logistic regression and receiver operating characteristic analysis were employed to examine survival status and determine optimal cut points. Results Among 1,104 patients, 57 died (5% mortality rate). Deceased patients had significantly higher B/rB/BOBI scores (mean: 98/98/92) than survivors (45/46/4.19) (p < 0.001), with ABSI showing no significance (p = 0.079). Each one-point increase in B/rB/BOBI scores correlated with a 1.09/1.09/2.34 times higher mortality risk (p < 0.001). The AUC for B score in predicting mortality was 0.926 (95% CI: 0.890, 0.962), with sensitivity and specificity values of 0.789 and 0.92, respectively, and an optimal cutoff point of 79. The AUC for the rB score was 0.927 (95% CI: 0.892, 0.962), with sensitivity and specificity values of 0.789 and 0.926, respectively, and an optimal cutoff point of 80. The AUC for the BOBI score was 0.901 (95% CI: 0.865, 0.937), with sensitivity and specificity values of 0.895 and 0.775, respectively, and an optimal cutoff point of 2. For patients with B scores above 79, their odds of mortality were 42.6 times higher than those with B scores of 79 or lower (95% CI: 22.6, 85.6, p < 0.001). Similarly, for patients with rB scores exceeding 80, their odds of mortality were 42.9 times higher than those with rB scores of 80 or lower (95% CI: 22.9, 84.8, p < 0.001). Finally, for patients with BOBI scores greater than 2, their odds of mortality were 17.8 times higher than those with BOBI scores of 2 or lower (95% CI: 9.88, 33.4, p < 0.001). Conclusion Our study underscores the vital role of mortality scoring systems in guiding clinical decision-making and resource allocation for burn patients, particularly within the Appalachian region served by the Cabell Huntington Hospital BICU. By leveraging tools such as the Baux, revised Baux, and BOBI scores, healthcare providers can identify high-risk patients early in their treatment course, facilitating personalized interventions and improving overall patient outcomes. Moreover, our findings highlight the significance of age and total body surface area burned as key determinants of mortality risk, emphasizing the need for tailored approaches to care for elderly patients and those with extensive burns. Continued research and refinement of mortality scoring systems are essential to further enhance their effectiveness and ensure optimal patient care in the challenging field of burn management.

A Rare Case of Extensive Basal Cell Carcinoma With Invasion of the Humerus: Excision and Immediate Reconstruction With Fibula Allograft, Plating, and Latissimus Dorsi Flap.

Basal cell carcinoma (BCC) is the most common skin cancer, and most of the reports have involved the head and neck, but it is rare for it to be highly invasive, with an invasion of long bone being extremely rare. A 73 year old woman presented with a giant BCC on her right arm. Magnetic resonance imaging suggested the involvement of the right humerus. Biopsy confirmed the nodular type of BCC. The patient underwent BCC excision including hemicortical humerus excision with fibula allograft and latissimus dorsi flap with a split-thickness skin graft. Excluding a transient radial nerve palsy, the patient's postoperative course was otherwise uncomplicated. Although BCC invasion into the long bone is extremely rare, the gold standard treatment is, as a rule, en bloc surgical resection with a wide variety of reconstructive techniques. This treatment is only possible through the collaboration of general surgery, orthopedics, and plastic surgery.

Global record of "ghost" nannofossils reveals plankton resilience to high CO2 and warming.

Predictions of how marine calcifying organisms will respond to climate change rely heavily on the fossil record of nannoplankton. Declines in calcium carbonate (CaCO3) and nannofossil abundance through several past global warming events have been interpreted as biocalcification crises caused by ocean acidification and related factors. We present a global record of imprint-or "ghost"-nannofossils that contradicts this view, revealing exquisitely preserved nannoplankton throughout an inferred Jurassic biocalcification crisis. Imprints from two further Cretaceous warming events confirm that the fossil records of these intervals have been strongly distorted by CaCO3 dissolution. Although the rapidity of present-day climate change exceeds the temporal resolution of most fossil records, complicating direct comparison with past warming events, our findings demonstrate that nannoplankton were more resilient to past events than traditional fossil evidence suggests.

The Importance of the Institution of a Robotic Curriculum on Resident Training and Performance.

In 2018, general surgery topped the number of robotic cases. Over 90% of residents participate, but only 65% of programs have a formal curriculum, and less than half track progress. Many are insufficient at training due to an observational role. This paper reviews Marshall University General Surgery Residency program's robotic curriculum, which started in 2018. The curriculum consists of a weekend course and simulations, enabling residents obtain certification. Residents participated in Intuitive's Resident Robotic Olympics with first place in 2019 and second and third place in 2020. For the 2021 year, the robotic curriculum was revised into phases based on year. Deadlines and forms help improve and track progress. It is important to develop a curriculum with a protocol for training, monitoring, and credentialing to ensure proficiency. Marshall University General Surgery robotic curriculum has been successful at improving robotic skill, enabling residents to obtain a robotic surgery certification upon graduation.

Algal plankton turn to hunting to survive and recover from end-Cretaceous impact darkness.

The end-Cretaceous bolide impact triggered the devastation of marine ecosystems. However, the specific kill mechanism(s) are still debated, and how primary production subsequently recovered remains elusive. We used marine plankton microfossils and eco-evolutionary modeling to determine strategies for survival and recovery, finding that widespread phagotrophy (prey ingestion) was fundamental to plankton surviving the impact and also for the subsequent reestablishment of primary production. Ecological selectivity points to extreme post-impact light inhibition as the principal kill mechanism, with the marine food chain temporarily reset to a bacteria-dominated state. Subsequently, in a sunlit ocean inhabited by only rare survivor grazers but abundant small prey, it was mixotrophic nutrition (autotrophy and heterotrophy) and increasing cell sizes that enabled the eventual reestablishment of marine food webs some 2 million years later.

On impact and volcanism across the Cretaceous-Paleogene boundary.

The cause of the end-Cretaceous mass extinction is vigorously debated, owing to the occurrence of a very large bolide impact and flood basalt volcanism near the boundary. Disentangling their relative importance is complicated by uncertainty regarding kill mechanisms and the relative timing of volcanogenic outgassing, impact, and extinction. We used carbon cycle modeling and paleotemperature records to constrain the timing of volcanogenic outgassing. We found support for major outgassing beginning and ending distinctly before the impact, with only the impact coinciding with mass extinction and biologically amplified carbon cycle change. Our models show that these extinction-related carbon cycle changes would have allowed the ocean to absorb massive amounts of carbon dioxide, thus limiting the global warming otherwise expected from postextinction volcanism.

Diversity decoupled from ecosystem function and resilience during mass extinction recovery.

The Chicxulub bolide impact 66 million years ago drove the near-instantaneous collapse of ocean ecosystems. The devastating loss of diversity at the base of ocean food webs probably triggered cascading extinctions across all trophic levels1-3 and caused severe disruption of the biogeochemical functions of the ocean, and especially disrupted the cycling of carbon between the surface and deep sea4,5. The absence of sufficiently detailed biotic data that span the post-extinction interval has limited our understanding of how ecosystem resilience and biochemical function was restored; estimates6-8 of ecosystem 'recovery' vary from less than 100 years to 10 million years. Here, using a 13-million-year-long nannoplankton time series, we show that post-extinction communities exhibited 1.8 million years of exceptional volatility before a more stable equilibrium-state community emerged that displayed hallmarks of resilience. The transition to this new equilibrium-state community with a broader spectrum of cell sizes coincides with indicators of carbon-cycle restoration and a fully functioning biological pump9. These findings suggest a fundamental link between ecosystem recovery and biogeochemical cycling over timescales that are longer than those suggested by proxies of export production7,8, but far shorter than the return of taxonomic richness6. The fact that species richness remained low as both community stability and biological pump efficiency re-emerged suggests that ecological functions rather than the number of species are more important to community resilience and biochemical functions.

Warm plankton soup and red herrings: calcareous nannoplankton cellular communities and the Palaeocene-Eocene Thermal Maximum.

Past global warming events such as the Palaeocene-Eocene Thermal Maximum (PETM-56 Ma) are attributed to the release of vast amounts of carbon into the ocean, atmosphere and biosphere with recovery ascribed to a combination of silicate weathering and organic carbon burial. The phytoplanktonic nannoplankton are major contributors of organic and inorganic carbon but their role in this recovery process remains poorly understood and complicated by their contribution to marine calcification. Biocalcification is implicated not only in long-term carbon burial but also both short-term positive and negative climatic feedbacks associated with seawater buffering and responses to ocean acidification. Here, we use exceptional records of preserved fossil coccospheres to reconstruct cell size distribution, biomass production (particulate organic carbon, POC) and (particulate) inorganic carbon (PIC) yields of three contrasting nannoplankton communities (Bass River-outer shelf, Maud Rise-uppermost bathyal, Shatsky Rise-open ocean) through the PETM onset and recovery. Each of the sites shows contrasting community responses across the PETM as a function of their taxic composition and total community biomass. Our results indicate that nannoplankton PIC:POC had no role in short-term climate feedback and, as such, their importance as a source of CO2 to the environment is a red herring. It is nevertheless likely that shifts to greater numbers of smaller cells at the shelf site in particular led to greater carbon transfer efficiency, and that nannoplankton productivity and export across the shelves had a significant modulating effect on carbon sequestration during the PETM recovery.This article is part of a discussion meeting issue 'Hyperthermals: rapid and extreme global warming in our geological past'.

Uremic Toxins Activates Na/K-ATPase Oxidant Amplification Loop Causing Phenotypic Changes in Adipocytes in In Vitro Models.

BACKGROUND: Oxidant stress plays a key role in the development of chronic kidney disease (CKD). Experimental CKD leads to accumulation of uremic toxins (UT) in the circulation resulting in increased ROS production, which in turn, is known to activate the Na/K-ATPase/ROS amplification loop. Studies in a murine model of obesity have shown that increased oxidative stress in plasma is due to increased ROS and cytokine production from dysfunctional adipocytes. Therefore, we hypothesized that adipocytes exposed to UTs will activate the Na/K-ATPase oxidant amplification loop causing redox imbalance and phenotypic alterations in adipocytes. We also aimed to demonstrate that the Na/K-ATPase signaling antagonist, pNaKtide, attenuates these pathophysiological consequences. METHODS: In the first set of experiments, 3T3-L1 murine pre-adipocytes were treated with varying concentrations of UTs, indoxyl sulfate (IS) (50, 100 and 250 µM) and p-cresol (50, 100 and 200 µM), with or without pNaKtide (0.7 µM) for five days in adipogenic media, followed by Oil Red O staining to study adipogenesis. RT-PCR analysis was performed to study expression of adipogenic, apoptotic and inflammatory markers, while DHE staining evaluated the superoxide levels in UT treated cells. In a second set of experiments, visceral fat was obtained from the West Virginian population. MSCs were isolated and cultured in adipogenic media for 14 days, which was treated with indoxyl sulfate (0, 25, 50 and 100 µM) with or without pNaKtide (1 µM). MSC-derived adipocytes were evaluated for morphological and molecular analysis of the above markers. RESULTS: Our results demonstrated that 3T3-L1 cells and MSCs-derived adipocytes, treated with UTs, exhibited a significant decrease in adipogenesis and apoptosis through activation of the Na/K-ATPase/ROS amplification loop. The treatment with pNaKtide in 3T3-L1 cells and MSC-derived adipocytes negated the effects of UTs and restored cellular redox in adipocytes. We noted a varying effect of pNaKtide, in adipocytes treated with UTs, on inflammatory markers, adipogenic marker and superoxide levels in 3T3-L1 cells and MSC-derived adipocytes. CONCLUSIONS: This study demonstrates for the first time that the Na/K-ATPase/ROS amplification loop activated by elevated levels of UTs has varying effect on phenotypic alterations in adipocytes in various in vitro models. Thus, we propose that, if proven in humans, inhibition of Na/K-ATPase amplification of oxidant stress in CKD patients may ultimately be a novel way to combat adipocyte dysfunction and metabolic imbalance in these patients.

Orbitally Forced Hyperstratification of the Oligocene South Atlantic Ocean.

Pelagic sediments from the subtropical South Atlantic Ocean contain geographically extensive Oligocene ooze and chalk layers that consist almost entirely of the calcareous nannofossil Braarudosphaera. Poor recovery and the lack of precise dating of these horizons in previous studies has limited the understanding of the number of acmes, their timing and durations, and therefore their likely cause. Here we present a high-resolution, astronomically tuned stratigraphy of Braarudosphaera oozes (29.5-27.9 Ma) from Ocean Drilling Program Site 1264 in the southeastern Atlantic Ocean. We identify seven episodes with highly abundant Braarudosphaera. Four of these acme events coincide with maxima and three with minima in the ~110 and 405-kyr paced eccentricity cycles. The longest lasting acme event corresponds to a pronounced minimum in the ~2.4-Myr eccentricity cycle. In the modern ocean, Braarudosphaera occurrences are limited to shallow marine and neritic settings, and the calcified coccospheres of Braarudosphaera are probably produced during a resting stage in the algal life cycle. Therefore, we hypothesize that the Oligocene acmes point to extensive and episodic (hyper) stratified surface water conditions, with a shallow pycnocline that may have served as a virtual seafloor and (partially/temporarily) prevented the coccospheres from sinking in the pelagic realm. We speculate that hyperstratification was either extended across large areas of the South Atlantic basin, through the formation of relatively hyposaline surface waters, or eddy contained through strong isopycnals at the base of eddies. Astronomical forcing of atmospheric and/or oceanic circulation could have triggered these conditions through either sustained rainfall over the open ocean and adjacent land masses or increased Agulhas Leakage.

Why marine phytoplankton calcify.

Calcifying marine phytoplankton-coccolithophores- are some of the most successful yet enigmatic organisms in the ocean and are at risk from global change. To better understand how they will be affected, we need to know "why" coccolithophores calcify. We review coccolithophorid evolutionary history and cell biology as well as insights from recent experiments to provide a critical assessment of the costs and benefits of calcification. We conclude that calcification has high energy demands and that coccolithophores might have calcified initially to reduce grazing pressure but that additional benefits such as protection from photodamage and viral/bacterial attack further explain their high diversity and broad spectrum ecology. The cost-benefit aspect of these traits is illustrated by novel ecosystem modeling, although conclusive observations remain limited. In the future ocean, the trade-off between changing ecological and physiological costs of calcification and their benefits will ultimately decide how this important group is affected by ocean acidification and global warming.

Coccolithophore calcification response to past ocean acidification and climate change.

Anthropogenic carbon dioxide emissions are forcing rapid ocean chemistry changes and causing ocean acidification (OA), which is of particular significance for calcifying organisms, including planktonic coccolithophores. Detailed analysis of coccolithophore skeletons enables comparison of calcite production in modern and fossil cells in order to investigate biomineralization response of ancient coccolithophores to climate change. Here we show that the two dominant coccolithophore taxa across the Paleocene-Eocene Thermal Maximum (PETM) OA global warming event (~56 million years ago) exhibited morphological response to environmental change and both showed reduced calcification rates. However, only Coccolithus pelagicus exhibits a transient thinning of coccoliths, immediately before the PETM, that may have been OA-induced. Changing coccolith thickness may affect calcite production more significantly in the dominant modern species Emiliania huxleyi, but, overall, these PETM records indicate that the environmental factors that govern taxonomic composition and growth rate will most strongly influence coccolithophore calcification response to anthropogenic change.

Evidence for global cooling in the Late Cretaceous.

The Late Cretaceous 'greenhouse' world witnessed a transition from one of the warmest climates of the past 140 million years to cooler conditions, yet still without significant continental ice. Low-latitude sea surface temperature (SST) records are a vital piece of evidence required to unravel the cause of Late Cretaceous cooling, but high-quality data remain illusive. Here, using an organic geochemical palaeothermometer (TEX86), we present a record of SSTs for the Campanian-Maastrichtian interval (~83-66 Ma) from hemipelagic sediments deposited on the western North Atlantic shelf. Our record reveals that the North Atlantic at 35 °N was relatively warm in the earliest Campanian, with maximum SSTs of ~35 °C, but experienced significant cooling (~7 °C) after this to <~28 °C during the Maastrichtian. The overall stratigraphic trend is remarkably similar to records of high-latitude SSTs and bottom-water temperatures, suggesting that the cooling pattern was global rather than regional and, therefore, driven predominantly by declining atmospheric pCO2 levels.

Exceptionally well-preserved Cretaceous microfossils reveal new biomineralization styles.

Calcareous microplankton shells form the dominant components of ancient and modern pelagic sea-floor carbonates and are widely used in palaeoenvironmental reconstructions. The efficacy of these applications, however, is dependent upon minimal geochemical alteration during diagenesis, but these modifying processes are poorly understood. Here we report on new biomineralization architectures of previously unsuspected complexity in calcareous cell-wall coverings of extinct dinoflagellates (pithonellids) from a Tanzanian microfossil-lagerstätte. These Cretaceous 'calcispheres' have previously been considered biomineralogically unremarkable but our new observations show that the true nature of these tests has been masked by recrystallization. The pristine Tanzanian fossils are formed from fibre-like crystallites and show archeopyles and exquisitely constructed opercula, demonstrating the dinoflagellate affinity of pithonellids, which has long been uncertain. The interwoven fibre-like structures provide strength and flexibility enhancing the protective function of these tests. The low-density wall fabrics may represent specific adaptation for oceanic encystment life cycles, preventing the cells from rapid sinking.

A Cenozoic record of the equatorial Pacific carbonate compensation depth.

Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.