Marine Micropaleontology最新文献

Marine benthic foraminifera diversity in extreme environments: A case study from the Edisto Bay (Ross Sea, Antarctica) 极端环境下的海洋底栖有孔虫多样性：以南极洲罗斯海埃迪斯托湾为例

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2026-01-22 DOI: 10.1016/j.marmicro.2026.102553

F. Caridi , L. Langone , A. Sartini , C. Morigi , G. Galli , P. Giordano , M. Bensi , V. Kovacevic , L. Ursella , N. Krauzig , A. Sabbatini

引用次数: 0

Gradual turnover in the composition of benthic foraminiferal assemblages across the Sinemurian/Pliensbachian boundary in the Transcarpathian Ukraine (Pieniny Klippen Belt, Eastern Carpathians) 乌克兰外喀尔巴阡山脉Sinemurian/Pliensbachian边界上底栖有孔虫组合的逐渐转换（东喀尔巴阡山脉Pieniny Klippen带）

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2026-01-17 DOI: 10.1016/j.marmicro.2026.102551

Štefan Józsa , Adam Tomašových , Ján Schlögl , Christian Meister , Vladimír Šimo

The Sinemurian/Pliensbachian boundary interval in the eastern part of the Pieniny Klippen Belt (Eastern Carpathians, Ukraine) is preserved in a succession formed by a marl-limestone alternation that was deposited in a low-energy, outer shelf environment on the NW margin of the Tethys shelf (Euroboreal Province). Assemblages with benthic foraminifers are diverse, with fifteen agglutinated species and 64 calcareous species. Although most species range across the Sinemurian/Pliensbachian boundary, the assemblages of agglutinated and calcareous benthic foraminifers exhibit a gradual and protracted change in abundance of species, genera, and functional morphogroups during this time interval. The increase in abundance of lenticular (C8) and elongated-flattened (C6) morphogroups and the decline in abundance of elongated morphogroups with a straight periphery (C8) across the boundary is gradual. This turnover in taxonomic and functional composition can be related to an increase in ventilation and bottom currents that decreased any incidences of oxygen depletion, reduced organic matter preservation, and allowed the onset of sponge biostromes during the earliest Pliensbachian. In contrast to stratigraphic changes in abundance of individual species, alpha species (mean = 21) and genus (mean = 11) diversity remains rather constant across the S/P boundary and the overall assemblage composition is persistently dominated by deposit-feeders and grazing omnivores both in the uppermost Sinemurian and the lowermost Pliensbachian. Therefore, although the overall shallowing-up trend in outer-shelf habitats contributed to directional changes in abundance of some species, genera and morphogroups, they did not induce any major turnover, extirpation or immigration at species or genus level.

Pieniny Klippen带（乌克兰东喀尔巴阡山脉）东部的Sinemurian/Pliensbachian边界段保存在一个由泥灰岩交替形成的序列中，该序列沉积在特提斯大陆架（欧洲北方省）西北缘的低能量外大陆架环境中。底栖有孔虫的组合是多样的，有15个凝集种和64个钙质种。虽然大多数物种分布在Sinemurian/Pliensbachian界线上，但在这段时间间隔内，黏结和钙质底栖有孔虫的种类、属和功能形态群的丰度表现出逐渐和持久的变化。透镜状（C8）和细长扁平（C6）形态群的丰度逐渐增加，边缘呈直线的细长型（C8）形态群的丰度逐渐下降。这种分类和功能成分的转换可能与通风和底流的增加有关，这减少了氧气消耗的发生率，减少了有机物的保存，并使海绵生物层在最早的Pliensbachian时期出现。与个体物种丰度的地层变化相反，α种（平均21种）和属（平均11种）多样性在S/P界线上保持相当稳定，总体组合组成在最上层的Sinemurian和最下层的Pliensbachian中都持续以沉积物食性动物和放牧杂食动物为主。因此，尽管陆架外生境的总体浅化趋势导致了某些物种、属和形态群丰度的方向性变化，但它们并未在种或属水平上引起任何重大的更替、灭绝或迁移。

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引用次数: 0

The promise of sedimentary ancient DNA as a proxy to understand Arctic Ocean palaeoecology and palaeoenvironments 沉积古DNA有望作为了解北冰洋古生态和古环境的代用物

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2026-01-16 DOI: 10.1016/j.marmicro.2026.102543

Flore M.D. Wijnands , Matt O'Regan , Helen K. Coxall , Peter D. Heintzman

The Arctic Ocean is changing rapidly due to global warming, but how this will impact marine Arctic ecosystems remains uncertain. Several Pleistocene interglacials, like Marine Isotope Stages (MIS) 5e, 9 and 11 form potential analogues to a future warmer Arctic and can give important insights on how Arctic ecosystems may respond to climate warming. However, micro- and nannofossils are scarce in many Pleistocene marine sediment cores, and are often not in agreement with biomarker data. Sedimentary ancient DNA (sedaDNA) is an emerging method that does not require the preservation of fossils and can therefore be used to detect taxa without any hard body parts, like most protist groups and zooplankton. Thanks to this method, it is now possible to detect organisms from all trophic layers of marine ecosystems. SedaDNA provides us with new opportunities to reconstruct past sea ice conditions, changes to ocean currents, and borealisation of the Arctic Ocean. Developments in bioinformatics software and new techniques like shotgun metagenomics and hybridisation capture, now enable the study of ancient DNA from Middle and even Early Pleistocene sediments. Moreover, the marine sedaDNA field is working towards detecting within-species genetic variation, which can provide information on population bottlenecks, recolonisation histories, and may lead to important insights for marine conservation. Combined with traditional proxies, sedaDNA is a powerful tool for Arctic Ocean palaeo-environmental reconstructions and can help provide critical proxy data to facilitate climate model calibrations and ultimately improve climate and environmental predictions for the Arctic.

由于全球变暖，北冰洋正在迅速变化，但这将如何影响北极海洋生态系统仍不确定。几个更新世间冰期，如海洋同位素阶段（MIS） 5e、9和11，形成了未来变暖的北极的潜在类似物，可以为北极生态系统如何应对气候变暖提供重要的见解。然而，在许多更新世海洋沉积物岩心中，微化石和纳米化石很少，而且往往与生物标志物数据不一致。沉积古DNA （sedaDNA）是一种新兴的方法，它不需要保存化石，因此可以用来检测没有任何坚硬身体部位的分类群，比如大多数原生生物群体和浮游动物。由于这种方法，现在可以从海洋生态系统的所有营养层检测生物。SedaDNA为我们提供了重建过去海冰状况、洋流变化和北冰洋北方化的新机会。生物信息学软件的发展和新技术，如散弹枪宏基因组学和杂交捕获，现在可以研究中更新世甚至早更新世沉积物中的古代DNA。此外，海洋sedaDNA领域正致力于探测物种内的遗传变异，这可以提供关于种群瓶颈、再定居历史的信息，并可能为海洋保护提供重要的见解。sedaDNA是北冰洋古环境重建的有力工具，可以帮助提供关键的代理数据，促进气候模式校准，最终改善北极的气候和环境预测。

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引用次数: 0

Corrigendum to <‘Evolution of Neogene fossil ceratoliths (Coccolithophores) by duplication title of article’> <[Marine Micropaleontology 201 (2025) Article 102530]> 应改正的错误,

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2026-01-01 DOI: 10.1016/j.marmicro.2025.102539

Carlos Lancis , J.E. Tent-Manclús , Jorge Lancis , Antonio Estévez , José-Abel Flores

引用次数: 0

X-rays have little impact on estimates of biodiversity from marine sedimentary ancient DNA metabarcoding x射线对海洋沉积古DNA元条形码生物多样性的估计影响不大

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2026-01-01 DOI: 10.1016/j.marmicro.2025.102540

Danielle M. Grant , Cooper D. Stacey , Christopher F.G. Hebda , Evan Morien , Zhen Li , Tyler J. Murchie , McIntyre A. Barrera , Linda Y. Rutledge

Sedimentary ancient DNA (sedaDNA) recovered from marine sediments offers valuable insights into past ocean biodiversity through ecosystem reconstructions ranging from decadal to glacial-interglacial timescales. The current best-practice in ancient DNA research is to collect new sediment cores with clean sampling protocols in an effort to prevent modern DNA contamination and minimize post-collection DNA degradation. However, new core collection can pose a barrier to research due to the high costs associated with project-specific expeditions; it also excludes leveraging existing sediment core archives. In general, the recommendation is founded on an abundance of caution rather than evidence-based guidelines. Here, we present a comparative study on the impacts of X-Radiography sediment analysis and different extraction methods on marine sedaDNA outcomes in an archived core to help develop such guidelines. We found that exposure to standard X-ray imaging had no significant impact on sedaDNA recovery, co-extraction of inhibitors (e.g. humic acids), metabarcoding diversity metrics, community structure or composition. The extraction method, however, has a significant impact on sedaDNA recovery/inhibition, diversity metrics, community structure, and composition. Laboratory methodological design for marine sedaDNA studies is, therefore, a critical consideration for future research, whereas standard X-ray screening by marine geoscientists appears benign to the parameters measured. Our results support the use of archived sediments for prospective sedaDNA work, thus reducing a considerable barrier to the field.

从海洋沉积物中恢复的沉积古DNA （sedaDNA）通过从年代际到冰期-间冰期时间尺度的生态系统重建，为了解过去的海洋生物多样性提供了有价值的见解。目前古代DNA研究的最佳实践是用干净的采样协议收集新的沉积物岩心，以努力防止现代DNA污染，并尽量减少收集后的DNA降解。然而，由于与特定项目的考察相关的高成本，新的核心收集可能会对研究构成障碍；它也不包括利用现有的沉积物岩心档案。总的来说，这项建议是建立在大量谨慎的基础上，而不是基于证据的指导方针。在这里，我们提出了一项关于x射线沉积物分析和不同提取方法对存档岩心中海洋sedaDNA结果的影响的比较研究，以帮助制定此类指南。我们发现，暴露于标准x射线成像对sedaDNA的恢复、抑制剂（如腐植酸）的共同提取、元条形码多样性指标、群落结构或组成没有显著影响。然而，提取方法对sedaDNA的恢复/抑制、多样性指标、群落结构和组成有显著影响。因此，海洋sedaDNA研究的实验室方法设计是未来研究的关键考虑因素，而海洋地球科学家的标准x射线筛查似乎对测量的参数有利。我们的研究结果支持将存档沉积物用于未来的sedaDNA工作，从而减少了现场的相当大的障碍。

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引用次数: 0

Biostratigraphy and paleoecology of benthic foraminifers from the Oligocene–Miocene at the equatorial carbonate platform, Northeastern Amazon Coast, Brazil 巴西东北亚马逊海岸赤道碳酸盐台地渐新世-中新世底栖有孔虫生物地层学与古生态学

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2026-01-01 DOI: 10.1016/j.marmicro.2026.102542

Mónica Andrea Benavides Pérez , Anna Andressa Evangelista Nogueira , Juan Sebastian Gomez-Neita

Benthic foraminifers are widely used as indicators of paleoenvironmental and paleoecological conditions in carbonate systems. This study focuses on the Neogene carbonate succession of the Pirabas Formation, exposed along the northeastern Amazon coast of Brazil, which is characterized by abundant and diverse fossil assemblages and stratigraphic correlations with subsurface deposits of the Barreirinhas and Marajó basins. The formation comprises mixed carbonate–siliciclastic sediments deposited during transgressive–regressive cycles from the Chattian to the Burdigalian, reflecting major changes in the morphology of the northern Brazilian margin. A total of 27 samples from the FPR-192 drill core (Primavera, Pará) were analyzed to investigate benthic foraminiferal assemblages. Paleoenvironmental, paleoecological, and paleobiogeographic interpretations were based on multivariate statistics and planktonic/benthic (P/B) ratios. Six biofacies and three broader associations were identified, documenting depositional environments ranging from restricted lagoonal and estuarine settings to middle–outer carbonate platform conditions. Assemblage composition indicates varying degrees of sediment reworking and downslope transport across the platform. A local benthic foraminiferal biozonation is proposed, including five Interval Zones (Amphistegina lessonii, Heterolepa dutemplei, Elphidium crispum, Siphonina pulchra, and Bolivina subcompressa) and one Assemblage Zone (Buccella peruviana). Biostratigraphic constraints place the succession mainly within the Oligocene–Early Miocene. Overall, the Pirabas Formation highlights the value of benthic foraminifers for reconstructing environmental dynamics and stratigraphic frameworks in tropical carbonate platforms.

底栖有孔虫被广泛用作碳酸盐岩系统古环境和古生态条件的指示物。本研究以巴西亚马逊河东北部海岸的Pirabas组新近系碳酸盐岩序列为研究对象，该组化石组合丰富多样，并与Barreirinhas盆地和Marajó盆地的地下沉积具有地层对比特征。该地层由海侵-海退旋回期间沉积的碳酸盐-硅屑混合沉积物组成，反映了巴西北部边缘的主要形态变化。对27个FPR-192岩心样品（Primavera, par）进行了底栖有孔虫组合分析。古环境、古生态和古生物地理解释基于多元统计和浮游/底栖生物（P/B）比率。确定了6种生物相和3种更广泛的组合，记录了从受限制的泻湖和河口环境到中-外碳酸盐岩台地条件的沉积环境。组合组成表明了不同程度的沉积物改造和跨台地的下坡搬运。提出了一个局部底栖有孔虫生物带，包括5个间隔带（Amphistegina lessonii、Heterolepa dutemplei、Elphidium crispum、Siphonina pulchra和Bolivina subcompressa）和1个组合带（Buccella peruviana）。生物地层限制将演替范围限定在渐新世-早中新世。总的来说，Pirabas组突出了底栖有孔虫在重建热带碳酸盐台地环境动力学和地层格架方面的价值。

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引用次数: 0

Machine learning approach to pore-proxy in benthic foraminifera for paleo-reconstruction of dissolved oxygen in a Lagoon 基于机器学习的底栖有孔虫孔隙代理方法在泻湖溶解氧古重建中的应用

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-12-18 DOI: 10.1016/j.marmicro.2025.102541

Rohan Subba , Anupam Ghosh , Akira Tsujimoto , Punyasloke Bhadury

The pore patterns in benthic foraminifera serve as a proxy for dissolved oxygen (DO) and nitrates (NO₃) in oxygen minimum zones (OMZs); however, their applicability in marginal marine settings, such as lagoons, estuaries and fjords, remains understudied. Chilika Lagoon (India) is undergoing a decrease in DO concentration due to eutrophication. Therefore, a novel machine learning (ML) approach is proposed for the quantitative reconstruction of DO based on the pore patterns of Ammonia parkinsoniana (benthic foraminifera). Random forest regression (RFR) and support vector regression (SVR) models were trained on the modern dataset of A. parkinsoniana (Rose Bengal-stained) for pore calibration. The SVR with a prediction accuracy of 87 % performed marginally better than the RFR (85 %). Subsequently, the SVR model was applied to the core sample for predicting DO across the period 1941–2023 CE. The predicted DO varies between 5.68 and 6.25 mgL⁻¹ (high oxic condition) with a model uncertainty of ±1.066 mgL⁻¹ for high oxic (3–6 mgL⁻¹) and ± 0.589 mgL⁻¹ for very high oxic (> 6 mgL⁻¹) conditions. The predicted DO has been verified with multi-proxy records from foraminifera (pore patterns and abundance) and sediment geochemistry (Total organic C, Mn and Cd). Among pore size, porosity % and circularity index, pore density (r = 0.84, p ≤ 0.001) is the main controlling factor on DO, which confirms pores as a reliable proxy for DO. The outcomes of this research also include the development of ForCAST (https://forcast-app.streamlit.app/), which is a freely accessible ML-based web application for DO predictions.

底栖有孔虫的孔隙形态代表了溶解氧（DO）和硝酸盐（NO3）在氧最小带（OMZs）中的分布；然而，它们在边缘海洋环境中的适用性，如泻湖、河口和峡湾，仍然没有得到充分的研究。由于富营养化，Chilika泻湖（印度）的DO浓度正在下降。因此，提出了一种新的机器学习（ML）方法，用于基于氨帕金森虫（底栖有孔虫）孔隙模式的定量重建DO。随机森林回归（RFR）和支持向量回归（SVR）模型在现代帕金萨娜（Rose Bengal-stained）数据集上进行校正。预测准确率为87%的SVR略好于RFR（85%）。随后，将SVR模型应用于核心样本，用于预测1941-2023 CE期间的DO。预测的DO在5.68和6.25 mgL−1（高氧条件）之间变化，高氧条件（3-6 mgL−1）的模型不确定度为±1.066 mgL−1，高氧条件（> 6 mgL−1）的模型不确定度为±0.589 mgL−1。通过有孔虫（孔隙模式和丰度）和沉积物地球化学（总有机C、Mn和Cd）的多重代理记录验证了预测的DO。孔径、孔隙率%和圆度指数中，孔隙密度（r = 0.84, p≤0.001）是影响DO的主要因素，证实了孔隙是DO的可靠指标。这项研究的成果还包括ForCAST （https://forcast-app.streamlit）的发展。app/)，这是一个免费访问的基于ml的web应用程序，用于DO预测。

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引用次数: 0

History of current circulation and bottom redox conditions in the central Okinawa Trough over the last 19 ka: Foraminiferal and element geochemical records 近19ka来冲绳海槽中部环流和底部氧化还原条件的历史：有孔虫和元素地球化学记录

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-12-04 DOI: 10.1016/j.marmicro.2025.102538

Feifei Wang , Bangqi Hu , Jingtao Zhao , Deqing Weng , Jianwei Guo , Xue Ding

The Okinawa Trough (OT) is a critical archive of western Pacific paleoceanography, yet the glacial-interglacial evolution of its circulation and bottom-water redox conditions remain poorly constrained. This study provides a multi-proxy reconstruction from core CS2 in the central OT, revealing a 19-ka history of Kuroshio Current (KC) and intermediate water ventilation for bottom-water oxygenation. Our results show that during the last glaciation, lower sea levels isolated the trough, reducing KC inflow as evidenced by decreased abundances of tropical-subtropical planktonic foraminifera and a shoaled thermocline. Concurrently, bottom-water hypoxia developed, indicated by elevated infaunal benthic foraminifera, lower Mn/Al ratios, and reduced CaCO₃ content, collectively suggesting that the absence or shift of KC was the primary driver of poor ventilation. Furthermore, an anti-phase relationship between hypoxia intensity and North Pacific Intermediate Water (NPIW) ventilation can be observed: enhanced NPIW ventilation (Heinrich Stadial 1 and Younger Dryas) corresponded to weakened hypoxia, whereas reduced ventilation during the Bølling/Allerød intensified hypoxia. The consistently low CaCO₃ content precluded the possibility of hypoxia caused by organic matter consumption, further supporting the conclusion that glacial NPIW ventilation might be another modulator of bottom water oxygenation. During the postglacial period, the return of the KC into the OT improved bottom-water ventilation by reducing stratification and alleviated hypoxia. This study elucidates the evolution of circulation and bottom-water redox conditions to better understand organic carbon burial in the OT. Furthermore, the redox history provides a key mid-latitude archive for assessing the influence of glacial NPIW.

冲绳海槽（OT）是西太平洋古海洋学的重要档案，但其环流和底水氧化还原条件的冰期-间冰期演化仍不清楚。本研究通过对东部中部CS2岩心的多代理重建，揭示了黑潮（KC）的19 ka历史和中水通气的底水氧合。结果表明，在末次冰期，较低的海平面隔离了海槽，减少了KC流入，热带-亚热带浮游有孔虫丰度减少，温跃层变浅。同时，底水缺氧发展，表现为底部底栖有孔虫数量增加，Mn/Al比降低，CaCO3含量降低，共同表明KC的缺失或转移是通风不良的主要驱动因素。此外，缺氧强度与北太平洋中水（NPIW）通气之间存在反相位关系：NPIW通气增强（Heinrich Stadial 1和Younger Dryas）对应于缺氧减弱，而Bølling/ allerd期间通气减少则强化了缺氧。持续的低CaCO3含量排除了有机物消耗引起缺氧的可能性，进一步支持了冰川NPIW通气可能是底水氧合的另一个调节剂的结论。在冰期后，KC返回到OT通过减少分层和缓解缺氧改善了底水通风。本研究阐明了循环演化和底水氧化还原条件，以更好地了解第三系有机碳埋藏。此外，氧化还原历史为评估冰川NPIW的影响提供了一个关键的中纬度档案。

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引用次数: 0

Linkages between modern benthic foraminiferal assemblages and environmental conditions at continental slope depths: From Baffin Bay to the Labrador Sea 现代底栖有孔虫组合与大陆斜坡深度环境条件之间的联系：从巴芬湾到拉布拉多海

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-12-01 DOI: 10.1016/j.marmicro.2025.102527

Joanna Davies , Anne Jennings , Alice Carter-Champion , William J. D'Andrea , Cara Fritz , Erin E. Gregory , David J. Harning , Robert Kelleher , Alan C. Mix , Katherine Stelling , Joseph S. Stoner , Maureen H. Walczak , Shannon Klotsko , Robert G. Hatfield , Brendan Reilly

Analysis of benthic foraminiferal assemblages and lipid biomarkers from surface sediments at 10 sites along the Greenland margin in Baffin Bay, in the Davis Strait, and Labrador Sea, spanning both shallow (<1000 m) and deep (>1000 m) water depths, reveals key differences related to environmental gradients. The relative abundance of calcareous and agglutinated foraminifera differentiates sites; deeper Baffin Bay sites are dominated by agglutinated taxa, while shallower Baffin Bay sites and a site in the Labrador Sea are characterised by calcareous taxa. Correlations amongst calcareous species and environmental parameters, specifically bottom water temperature and salinity from CTD casts, sea ice, open water phytoplankton biomarker concentrations and total organic carbon, suggest that carbonate dissolution is associated with seasonal sea-ice formation, cold and less saline bottom waters, and high primary productivity. Cassidulina neoteretis and Cassidulina reniforme are abundant at almost all sites, reflecting the presence of chilled Atlantic sourced water. In eastern Davis Strait, sea ice is absent for much of the year and the faunal assemblage is dominated by calcareous taxa, specifically Nonionellina labradorica, Elphidium clavatum, Epistominella arctica and Melonis barleeanus. In the Labrador Sea, which is characterised by warmer bottom waters and less seasonal sea-ice, the fauna differs from Baffin Bay, dominated by Buccella frigida and Nonionella iridea. Agglutinated taxa, particularly Portatrochammina bipolaris, Hormosinelloides guttifera, Lagenammina difflugiformis and Recurvoides turbinatus, dominate Baffin Bay sites, where cold, sea-ice-influenced bottom waters prevail. Linking faunal assemblages, including agglutinated taxa, to environmental datasets is critical for paleoenvironmental reconstructions, especially in regions where calcareous foraminifera are poorly preserved.

对巴芬湾格陵兰边缘、戴维斯海峡和拉布拉多海10个地点的表层沉积物中底栖有孔虫组合和脂质生物标志物的分析，跨越了浅（<1000 m）和深（>1000 m）水深，揭示了与环境梯度相关的关键差异。钙质有孔虫和凝集有孔虫的相对丰度不同；较深的巴芬湾遗址以粘连类群为主，而较浅的巴芬湾遗址和拉布拉多海的一个遗址以钙质类群为特征。钙质种类与环境参数的相关性，特别是CTD cast的底水温和盐度、海冰、开放水域浮游植物生物标志物浓度和总有机碳，表明碳酸盐溶解与季节性海冰形成、寒冷和低盐底水以及高初级生产力有关。几乎在所有的地点都有大量的小木犀草（Cassidulina neteretis）和长形木犀草（Cassidulina reniforme），这反映了来自大西洋的冷水的存在。在戴维斯海峡东部，海冰常年不存在，动物群以钙质类群为主，特别是Nonionellina labradorica、Elphidium clavatum、Epistominella arctica和Melonis barleeanus。在拉布拉多海，其特点是温暖的底部海水和较少的季节性海冰，动物群不同于巴芬湾，主要是Buccella frigida和Nonionella iridea。凝集的类群，特别是双极紫菀、花叶草、散斑紫菀和turbinatus，主导着巴芬湾的地点，在那里，寒冷，海冰影响的底部水占优势。将动物组合（包括凝集类群）与环境数据集联系起来对于古环境重建至关重要，特别是在钙质有孔虫保存较差的地区。

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引用次数: 0

Evolution of Neogene fossil ceratoliths (Coccolithophores) by duplication 新近系角藻化石（球石藻）的复制演化

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-12-01 DOI: 10.1016/j.marmicro.2025.102530

Carlos Lancis , J.E. Tent-Manclús , Jorge Lancis , Antonio Estévez , José-Abel Flores

The calcareous nannofossils of the genus Ceratolithus, known for their horseshoe shape (referred to as ceratolith), evolved from the Orthorhabdus rugosus, a rod-shape nannolith with three rodded blades (sinistral, median, and dextral). The sinistral and median blades gave rise to the sinistral and dextral arms of the ceratolith, while the dextral blade was reduced to a keel. The first species of the Ceratolithus genus branch is Ceratolithus finifer, which rapidly evolved into Ceratolithus acutus. Around at the same time, the merging of three duplicated, delicate horseshoe-shaped structures derived from C. finifer - two equivalent and one a mirror image of the other- resulted in the short-lived Poralithus atlanticus (5.32 to 5.17 Ma). Later on, two duplicated horseshoe-shaped structures oriented at an angle of approximately 45° and fused at the horseshoe's close side, produced Amaurolithus tricorniculatus (5.30 to 4.86 Ma). The crystallographic features of A. tricorniculatus points to a possible origin by two duplicated Ceratolithus-type horseshoes (birefringent in its stable layout) and derived from C. finifer. Being the type species of the Amaurolithus genus and also evolving from the Ceratolithus branch, then the early ‘Amaurolithus’, which evolved from O. rugosus, have been placed in a newly defined Protoamaurolithus genus, as Protoamaurolithus primus and Protoamaurolithus delicatus. Best-preserved Amaurolithus tricorniculatus specimens are observed to show birefringence and the broken and poor-preserved use to be slightly or not birefringence. Poralithus atlanticus and Amaurolithus tricorniculatus appeared instantly in the geologic record, indicative of instantaneous speciation, resulting from horseshoe-structure duplication process.

角鼻石属的钙质纳米化石，以其马蹄形而闻名（称为角鼻石），由Orthorhabdus rugosus进化而来，Orthorhabdus rugosus是一种杆状的纳米石，有三个杆状的叶片（左旋、中旋和右旋）。左旋和中旋叶片形成了角状石的左旋和右旋臂，而右旋叶片则退化为龙骨。角鼻蠓属分支的第一个种是尖角角蠓，并迅速进化为尖角蠓。大约在同一时间，来自C. finifer的三个重复的、精致的马蹄形结构的合并——两个相同，一个是另一个的镜像——产生了寿命较短的大西洋Poralithus（5.32至5.17 Ma）。后来，两个重复的马蹄形结构以约45°的角度定向，并在马蹄形的近侧融合，产生了Amaurolithus tricorniculatus（5.30至4.86 Ma）。a . tricorniculatus的晶体学特征表明其可能来源于C. finifer的两个重复的ceratolithus型马蹄铁（其稳定的双折射结构）。作为毛毛蜥属的模式种，也是由角鼻蜥分支进化而来的，因此早期的“毛毛蜥”从O. rugosus进化而来，被置于一个新定义的原毛毛蜥属，即原毛毛蜥primus和原毛毛蜥delicatus。保存较好的三环蛇标本显示双折射，而破损和保存较差的标本显示轻微或无双折射。在地质记录中，大西洋Poralithus atlanticus和三环蛇amaurollithus tricorniculatus是瞬时出现的，表明它们是由马蹄形结构复制过程产生的瞬时物种形成。

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引用次数: 0