This is the first comprehensive systematic study of the Middle Jurassic scleractinian corals from the Qiangtang block, based on 225 fossil coral specimens collected from the Buqu Formation in the Biluocuo area of northern Xizang (Tibet). Three species of three genera are identified: Montlivaltia zangbeiensis, Pseudocoenia slovenica, and Kobyastraea coquandi. The assemblage is dominated by solitary Montlivaltia (92.44%), with significantly fewer compound colonies of Pseudocoenia (4.89%) and Kobyastraea (2.67%). Comparative analysis reveals that the Qiangtang coral fauna shows strong affinities with contemporaneous Tethyan assemblages, particularly showing the closest similarities to coral communities from East-Central Iran. These findings provide compelling evidence for a close palaeobiogeographic connection between the Qiangtang block and the central Tethyan region during the Middle Jurassic.
{"title":"Scleractinian corals from the Middle Jurassic Buqu Formation, Qiangtang block and their palaeogeographic implications","authors":"Xiu-Ping Zhu , Kun Liang , Wei-Hua Liao , Jia-Run Yin , Xin Rao , Yi-Chun Zhang","doi":"10.1016/j.palwor.2025.200978","DOIUrl":"10.1016/j.palwor.2025.200978","url":null,"abstract":"<div><div>This is the first comprehensive systematic study of the Middle Jurassic scleractinian corals from the Qiangtang block, based on 225 fossil coral specimens collected from the Buqu Formation in the Biluocuo area of northern Xizang (Tibet). Three species of three genera are identified: <em>Montlivaltia zangbeiensis</em>, <em>Pseudocoenia slovenica</em>, and <em>Kobyastraea coquandi</em>. The assemblage is dominated by solitary <em>Montlivaltia</em> (92.44%), with significantly fewer compound colonies of <em>Pseudocoenia</em> (4.89%) and <em>Kobyastraea</em> (2.67%). Comparative analysis reveals that the Qiangtang coral fauna shows strong affinities with contemporaneous Tethyan assemblages, particularly showing the closest similarities to coral communities from East-Central Iran. These findings provide compelling evidence for a close palaeobiogeographic connection between the Qiangtang block and the central Tethyan region during the Middle Jurassic.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"35 1","pages":"Article 200978"},"PeriodicalIF":1.7,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-26DOI: 10.1016/j.palwor.2025.200979
Shu-Ran Tang , Qi-Jia Li , Hui Jia , Jian-Hua Jin , Cheng Quan
Plant development is highly influenced by ecological conditions, with different latitudes hosting vegetation with distinct component and ecological strategies. However, the ecological strategies of low-latitude plants in deep time remain poorly understood. In this study, we examine well-preserved fossil leaves from the upper Miocene of Beihai, low-latitude China, and describe three species of Calophyllum (Calophyllaceae) based on morphological and anatomical characteristics. Using leaf economic concepts, the ecological strategy of Calophyllum during the late Miocene is also evaluated. Our results suggest that all the three fossil species have leaf mass per area (LMA) higher than their nearest living relatives. It appears that the longer leaf lifespan driven by longer growing season likely contributed to the high LMA and hence the slow-return ecological strategy of Calophyllum in the late Miocene hereof. This study highlights the leaf lifespan in regulation of plant ecological strategies and provides insights into the palaeoecology of low-latitude vegetation during the late Miocene.
{"title":"Calophyllum (Calophyllaceae) with high leaf mass per area from the upper Miocene of Beihai, low-latitude China","authors":"Shu-Ran Tang , Qi-Jia Li , Hui Jia , Jian-Hua Jin , Cheng Quan","doi":"10.1016/j.palwor.2025.200979","DOIUrl":"10.1016/j.palwor.2025.200979","url":null,"abstract":"<div><div>Plant development is highly influenced by ecological conditions, with different latitudes hosting vegetation with distinct component and ecological strategies. However, the ecological strategies of low-latitude plants in deep time remain poorly understood. In this study, we examine well-preserved fossil leaves from the upper Miocene of Beihai, low-latitude China, and describe three species of <em>Calophyllum</em> (Calophyllaceae) based on morphological and anatomical characteristics. Using leaf economic concepts, the ecological strategy of <em>Calophyllum</em> during the late Miocene is also evaluated. Our results suggest that all the three fossil species have leaf mass per area (LMA) higher than their nearest living relatives. It appears that the longer leaf lifespan driven by longer growing season likely contributed to the high LMA and hence the slow-return ecological strategy of <em>Calophyllum</em> in the late Miocene hereof. This study highlights the leaf lifespan in regulation of plant ecological strategies and provides insights into the palaeoecology of low-latitude vegetation during the late Miocene.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"34 6","pages":"Article 200979"},"PeriodicalIF":1.7,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-19DOI: 10.1016/j.palwor.2025.200977
Yun-Xia Jia , Wen-Chao Zhang , Li-Jun Tian , Zhi-Lin He , Zhao Wang , Qing-Chun Tian
The modern Asian environment comprises monsoon-dominated East Asia and the arid Asian interior. However, when and how the modern climatic environment of Asia evolved remains controversial. Quantitative and spatio-temporal paleovegetation reconstructions are crucial for addressing this issue. We compiled 10 well-dated pollen records across the northeastern Tibetan Plateau, stretching from western China into eastern China. We used the biomization method to generate a set of biome scores and landscape openness spanning the interval from the Eocene to Recent. Biome reconstructions reveal that five dominant vegetation types have attained the highest scores since ∼42 Ma, namely warm mixed forest, temperate deciduous forest, cool mixed forest, steppe, and desert. Spatially, our results reveal that the climate was predominantly wetter in the west than in the east during the Paleogene, as evidenced by the higher values of landscape openness in the west. Since ∼24 Ma this climate configuration has reversed. Temporally, our results reveal wet-dry climatic fluctuations during the Paleogene, as evidenced by the coexistence of open vegetation and forest vegetation. Then, our results reveal a reorganization of the climatic environment since ∼24 Ma, as evidenced by the presence of forest vegetation types in the east and decreasing trend of landscape openness in the west. Subsequently, our results reveal region-wide aridification since ∼8 Ma, as evidenced by the negative values of landscape openness in many regions. Together with previous paleoclimate records, we infer that the retreat of the Paratethys Sea was responsible for wet-dry fluctuations during the Paleogene. We also infer that the uplift of Central Xizang (Tibet) triggered the permanent reorganization of the Asian environment at the Oligocene/Miocene transition, and that global cooling promoted the subsequent aridification trend.
{"title":"Spatiotemporal pattern of vegetation evolution in northeastern Tibetan Plateau during the Cenozoic and its climatic significance","authors":"Yun-Xia Jia , Wen-Chao Zhang , Li-Jun Tian , Zhi-Lin He , Zhao Wang , Qing-Chun Tian","doi":"10.1016/j.palwor.2025.200977","DOIUrl":"10.1016/j.palwor.2025.200977","url":null,"abstract":"<div><div>The modern Asian environment comprises monsoon-dominated East Asia and the arid Asian interior. However, when and how the modern climatic environment of Asia evolved remains controversial. Quantitative and spatio-temporal paleovegetation reconstructions are crucial for addressing this issue. We compiled 10 well-dated pollen records across the northeastern Tibetan Plateau, stretching from western China into eastern China. We used the biomization method to generate a set of biome scores and landscape openness spanning the interval from the Eocene to Recent. Biome reconstructions reveal that five dominant vegetation types have attained the highest scores since ∼42 Ma, namely warm mixed forest, temperate deciduous forest, cool mixed forest, steppe, and desert. Spatially, our results reveal that the climate was predominantly wetter in the west than in the east during the Paleogene, as evidenced by the higher values of landscape openness in the west. Since ∼24 Ma this climate configuration has reversed. Temporally, our results reveal wet-dry climatic fluctuations during the Paleogene, as evidenced by the coexistence of open vegetation and forest vegetation. Then, our results reveal a reorganization of the climatic environment since ∼24 Ma, as evidenced by the presence of forest vegetation types in the east and decreasing trend of landscape openness in the west. Subsequently, our results reveal region-wide aridification since ∼8 Ma, as evidenced by the negative values of landscape openness in many regions. Together with previous paleoclimate records, we infer that the retreat of the Paratethys Sea was responsible for wet-dry fluctuations during the Paleogene. We also infer that the uplift of Central Xizang (Tibet) triggered the permanent reorganization of the Asian environment at the Oligocene/Miocene transition, and that global cooling promoted the subsequent aridification trend.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"34 6","pages":"Article 200977"},"PeriodicalIF":1.7,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-13DOI: 10.1016/j.palwor.2025.200970
Şükrü Acar, Alper Bozkurt
The Priabonian (Eocene) shallow-water carbonates of the Malatya region (eastern Türkiye) contain rich benthic foraminiferal assemblages. A new calcarinid genus (Hereceina n. gen.) with its type species (Hereceina spinigera n. gen. n. sp.) and two Borelis species (Borelis dizerae n. sp. and Borelis sozerii n. sp.) are systematically described from these deposits. A late Priabonian age, corresponding to SBZ 20, is assigned to the new taxa based on the co-occurrence of biostratigraphic markers such as Heterostegina gracilis and Spiroclypeus carpaticus. Based on microfacies studies, Hereceina spinigera n. gen. n. sp. is documented from inner to proximal middle ramp environments that were influenced by wave and current action. The introduction of these new Borelis species with Y-shaped septula from the upper Priabonian of the region provides new insights into the evolutionary history of the genus. This study highlights the significant potential of the new taxa that appeared during the Eocene–Oligocene marine extinctions to serve as valuable biostratigraphic markers at Tethyan localities.
{"title":"New larger foraminiferal taxa (Hereceina n. gen. and new Borelis species) from upper Priabonian of eastern Türkiye (Turkey): Biostratigraphic and paleoecological implications","authors":"Şükrü Acar, Alper Bozkurt","doi":"10.1016/j.palwor.2025.200970","DOIUrl":"10.1016/j.palwor.2025.200970","url":null,"abstract":"<div><div>The Priabonian (Eocene) shallow-water carbonates of the Malatya region (eastern Türkiye) contain rich benthic foraminiferal assemblages. A new calcarinid genus (<em>Hereceina</em> n. gen.) with its type species (<em>Hereceina spinigera</em> n. gen. n. sp.) and two <em>Borelis</em> species (<em>Borelis dizerae</em> n. sp. and <em>Borelis sozerii</em> n. sp.) are systematically described from these deposits. A late Priabonian age, corresponding to SBZ 20, is assigned to the new taxa based on the co-occurrence of biostratigraphic markers such as <em>Heterostegina gracilis</em> and <em>Spiroclypeus carpaticus</em>. Based on microfacies studies, <em>Hereceina spinigera</em> n. gen. n. sp. is documented from inner to proximal middle ramp environments that were influenced by wave and current action. The introduction of these new <em>Borelis</em> species with Y-shaped septula from the upper Priabonian of the region provides new insights into the evolutionary history of the genus. This study highlights the significant potential of the new taxa that appeared during the Eocene–Oligocene marine extinctions to serve as valuable biostratigraphic markers at Tethyan localities.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"34 6","pages":"Article 200970"},"PeriodicalIF":1.7,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145418149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-09DOI: 10.1016/j.palwor.2025.200969
Zhao-Yang Yi , Zhen Yan , Xin Wei , Kai Wang , Bing Shen , Jian-Bo Liu
The relationship between microbial calcification and atmospheric CO2 levels is a critical aspect of Earth’s biogeochemical evolution. This study presents the first detailed investigation of micro- and mesoscopic features of stromatolites from the 2.1 Ga Dashiling Formation of the Hutuo Group in Wutai area, North China, one of the best preserved microbialites during the Great Oxidation Event (GOE). The study identifies three types of microclots (microclots-1, -2 and -3) as key contributors to the formation of stromatolitic laminae in the Dashiling Formation. These microclots form layered, meshed, and dendritic microclotted laminae, characterized by alternation of light and dark laminae, with lighter laminae being sparsely distributed and darker laminae densely distributed. These alternations reflect the periodic growth and decay of microbial communities in response to dynamic environmental changes. The microclots and microclotted laminae in the Dashiling Formation exhibit evidence for microbial calcification, suggesting that atmospheric CO2 levels during the early Paleoproterozoic may have been lower than previously estimated. Previous studies have proposed that microbial calcification occurs extensively only when atmospheric CO2 declines to ∼10 times the present atmospheric level. The well-preserved microclots and calcified microbial structures in the Dashiling Formation suggest that atmospheric CO2 levels during the GOE may have approached or fallen below this threshold. While increased atmospheric O2 levels during the GOE may have influenced microbial calcification, our results indicate that declining CO2 levels played a more direct role in facilitating carbonate precipitation. These findings refine the understanding of the interplay between microbial activities, atmospheric CO2 decline, and carbonate saturation during the GOE, offering new insights into early Earth’s carbon cycle dynamics.
{"title":"Microclots in early Paleoproterozoic stromatolites from Dashiling Formation, Wutai, North China: Implications for microbial calcification and atmospheric CO2 levels during Great Oxidation Event","authors":"Zhao-Yang Yi , Zhen Yan , Xin Wei , Kai Wang , Bing Shen , Jian-Bo Liu","doi":"10.1016/j.palwor.2025.200969","DOIUrl":"10.1016/j.palwor.2025.200969","url":null,"abstract":"<div><div>The relationship between microbial calcification and atmospheric CO<sub>2</sub> levels is a critical aspect of Earth’s biogeochemical evolution. This study presents the first detailed investigation of micro- and mesoscopic features of stromatolites from the 2.1 Ga Dashiling Formation of the Hutuo Group in Wutai area, North China, one of the best preserved microbialites during the Great Oxidation Event (GOE). The study identifies three types of microclots (microclots-1, -2 and -3) as key contributors to the formation of stromatolitic laminae in the Dashiling Formation. These microclots form layered, meshed, and dendritic microclotted laminae, characterized by alternation of light and dark laminae, with lighter laminae being sparsely distributed and darker laminae densely distributed. These alternations reflect the periodic growth and decay of microbial communities in response to dynamic environmental changes. The microclots and microclotted laminae in the Dashiling Formation exhibit evidence for microbial calcification, suggesting that atmospheric CO<sub>2</sub> levels during the early Paleoproterozoic may have been lower than previously estimated. Previous studies have proposed that microbial calcification occurs extensively only when atmospheric CO<sub>2</sub> declines to ∼10 times the present atmospheric level. The well-preserved microclots and calcified microbial structures in the Dashiling Formation suggest that atmospheric CO<sub>2</sub> levels during the GOE may have approached or fallen below this threshold. While increased atmospheric O<sub>2</sub> levels during the GOE may have influenced microbial calcification, our results indicate that declining CO<sub>2</sub> levels played a more direct role in facilitating carbonate precipitation. These findings refine the understanding of the interplay between microbial activities, atmospheric CO<sub>2</sub> decline, and carbonate saturation during the GOE, offering new insights into early Earth’s carbon cycle dynamics.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"34 5","pages":"Article 200969"},"PeriodicalIF":1.7,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-06DOI: 10.1016/j.palwor.2025.200968
Zainab M. El-Noamani, Wagieh E. El-Saadawi, Marwah M. Kamal El-Din, Nermeen A. Ziada
This study examines 12 well-preserved specimens collected from the Miocene Moghra and Gebel Khashab formations at six sites in the northern part of the Western Desert of Egypt. The results reveal distinct anatomical features for each of the four morphospecies (namely Palmoxylon aschersoni Schenk, P. cf. aschersoni Schenk, P. lacunosum (Unger) Felix, and P. libycum (Stenzel) Kräusel), confirming their identification and classification within the subfamily Coryphoideae. The paleoclimatic conditions for each species are interpreted based on key ecologically-based anatomical traits, such as the number of metaxylem elements and the nature of ground tissue. These findings indicate that the four recorded species reflect different paleoenvironments and depositional conditions, suggesting that they were transported by water from their original growth sites to their current locations, resulting in an intermingling of forest forms in the northern Western Desert. An overview of the fossil record of the subfamily Coryphoideae in Africa is also provided.
这项研究检查了在埃及西部沙漠北部的六个地点从中新世Moghra和Gebel Khashab地层收集的12个保存完好的标本。结果揭示了四个形态种(Palmoxylon aschersoni Schenk， P. cf. aschersoni Schenk， P. lacunosum （Unger) Felix和P. libycum (Stenzel) Kräusel）各自的解剖特征，证实了它们在蕨亚科中的鉴定和分类。每个物种的古气候条件都是基于关键的生态解剖学特征来解释的，比如韧皮部元素的数量和地面组织的性质。这些发现表明，这四种记录物种反映了不同的古环境和沉积条件，表明它们被水从原始生长地点转移到现在的位置，导致西部沙漠北部森林形式的混合。本文还概述了非洲斑蝶亚科的化石记录。
{"title":"Anatomy and paleoclimatic implications of Cenozoic Coryphoideae palm wood species in Egypt","authors":"Zainab M. El-Noamani, Wagieh E. El-Saadawi, Marwah M. Kamal El-Din, Nermeen A. Ziada","doi":"10.1016/j.palwor.2025.200968","DOIUrl":"10.1016/j.palwor.2025.200968","url":null,"abstract":"<div><div>This study examines 12 well-preserved specimens collected from the Miocene Moghra and Gebel Khashab formations at six sites in the northern part of the Western Desert of Egypt. The results reveal distinct anatomical features for each of the four morphospecies (namely <em>Palmoxylon aschersoni</em> Schenk, <em>P</em>. cf. <em>aschersoni</em> Schenk, <em>P</em>. <em>lacunosum</em> (Unger) Felix, and <em>P</em>. <em>libycum</em> (Stenzel) Kräusel), confirming their identification and classification within the subfamily Coryphoideae. The paleoclimatic conditions for each species are interpreted based on key ecologically-based anatomical traits, such as the number of metaxylem elements and the nature of ground tissue. These findings indicate that the four recorded species reflect different paleoenvironments and depositional conditions, suggesting that they were transported by water from their original growth sites to their current locations, resulting in an intermingling of forest forms in the northern Western Desert. An overview of the fossil record of the subfamily Coryphoideae in Africa is also provided.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"34 5","pages":"Article 200968"},"PeriodicalIF":1.7,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-06DOI: 10.1016/j.palwor.2025.200967
E. Kristal Rueda , Guillermo L. Albanesi , Gladys Ortega
This contribution reports a new species, Trapezognathus morenensis n. sp., from the upper levels of the Acoite Formation outcropping in the El Moreno area of the Cordillera Oriental, northwestern Argentina. This species occurs together with Trapezognathus diprion, Costiconus sp., Drepanodus arcuatus, Drepanoistodus costatus, D. forceps, D. pitjanti, Erraticodon patu, Gothodus costulatus, G. andinus, Kallidontus sp., Paltodus subaequalis, Parapanderodus cf. striatus, Paroistodus parallelus, Protopanderodus rectus, Zentagnathus argentinensis, Gothodus spp., and Drepanoistodontid gen. et sp. indet. Trapezognathus morenensis n. sp. exhibits intermediate characteristics between T. diprion and T. quadrangulum, and also displays a close relationship with early species of the genus Baltoniodus. The conodont assemblage allows for the identification of the Gothodus andinus and Trapezognathus diprion zones, indicating a middle to late Floian (Early Ordovician) age. In addition, the boundary between the Gothodus andinus Zone and the succeeding Trapezognathus diprion Zone is defined by the first occurrence datum of Trapezognathus diprion within the same stratigraphic section, representing the first documented instance of this boundary. The revision of associated taxa with reported Trapezognathus spp. suggests that the definition of the Floian–Dapingian boundary still requires verification in the Cordillera Oriental of Argentina.
{"title":"New conodont fauna from the Floian (Lower Ordovician) Acoite Formation, Cordillera Oriental, Argentina","authors":"E. Kristal Rueda , Guillermo L. Albanesi , Gladys Ortega","doi":"10.1016/j.palwor.2025.200967","DOIUrl":"10.1016/j.palwor.2025.200967","url":null,"abstract":"<div><div>This contribution reports a new species, <em>Trapezognathus morenensis</em> n. sp., from the upper levels of the Acoite Formation outcropping in the El Moreno area of the Cordillera Oriental, northwestern Argentina. This species occurs together with <em>Trapezognathus diprion</em>, <em>Costiconus</em> sp., <em>Drepanodus arcuatus</em>, <em>Drepanoistodus costatus</em>, <em>D</em>. <em>forceps</em>, <em>D</em>. <em>pitjanti</em>, <em>Erraticodon patu</em>, <em>Gothodus costulatus</em>, <em>G</em>. <em>andinus</em>, <em>Kallidontus</em> sp., <em>Paltodus subaequalis</em>, <em>Parapanderodus</em> cf. <em>striatus</em>, <em>Paroistodus parallelus</em>, <em>Protopanderodus rectus</em>, <em>Zentagnathus argentinensis</em>, <em>Gothodus</em> spp., and Drepanoistodontid gen. et sp. indet. <em>Trapezognathus morenensis</em> n. sp. exhibits intermediate characteristics between <em>T</em>. <em>diprion</em> and <em>T</em>. <em>quadrangulum</em>, and also displays a close relationship with early species of the genus <em>Baltoniodus</em>. The conodont assemblage allows for the identification of the <em>Gothodus andinus</em> and <em>Trapezognathus diprion</em> zones, indicating a middle to late Floian (Early Ordovician) age. In addition, the boundary between the <em>Gothodus andinus</em> Zone and the succeeding <em>Trapezognathus diprion</em> Zone is defined by the first occurrence datum of <em>Trapezognathus diprion</em> within the same stratigraphic section, representing the first documented instance of this boundary. The revision of associated taxa with reported <em>Trapezognathus</em> spp. suggests that the definition of the Floian–Dapingian boundary still requires verification in the Cordillera Oriental of Argentina.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"34 5","pages":"Article 200967"},"PeriodicalIF":1.7,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-02DOI: 10.1016/j.palwor.2025.200966
Mennat-Allah T. El Hussieny, Magdy S. Mahmoud, Amr S. Deaf
Palynological organic matter (POM) of the Neogene succession from the Sidi Salim-1 well, located in the onshore Nile Delta, Egypt (Eastern Mediterranean), suggests a wide range of environments, from deltaic to offshore marine. These environments were discriminated by the overall palynofacies composition, including indicative dinoflagellate cysts, mainly Spiniferites and Selenopemphix. Near-shore marine environment was interpreted for the Middle Miocene (Langhian–Serravallian) Sidi Salim Formation. Deltaic to shallow marine environments were suggested for the Qawasim (Miocene) and Kafr El Sheikh (Pliocene) formations, while the distant (offshore) marine setting was established in the Pliocene Abu Madi Formation. This deeper environment, of the Abu Madi Formation, can be used to confirm a previous documentation of an Early Pliocene progressive drowning of an incised valley, related to the Messinian Salinity Crises (MSC) events, by the late Messinian sea level drop in the Mediterranean. Suboxic to anoxic conditions existed during deposition of the investigated well succession. Anoxia was confirmed by the occurrence of imprints of pyrite crystals across much of the well succession. The occurrence of abundant Poaceae pollen may suggest widespread dry grassland vegetation during deposition of the Neogene sediments of the well. In a regional context, the Neogene environments in the Nile Delta area vary according to the relative position of the investigated sediments, due to structural, palaeogeographic and basinal settings. The recovered palynofacies fluctuated between amorphous organic matter (AOM)-dominated and phytoclast-dominated categories, mostly of the kerogen type II, which is capable of producing oil and gas. The visual assessment of the spore coloration index (SCI) of thin-walled trilete spores in the well section, shows values ranging between 5 and 8, confirming a thermally mature organic matter and, consequently, can be potential source rocks.
位于埃及尼罗河三角洲（东地中海）西迪萨利姆-1井新近系地层的孢粉有机质（POM）显示了从三角洲到近海海洋的广泛环境。这些环境可通过孢粉相的整体组成来区分，包括指示性鞭毛藻囊，主要是刺虫和硒藻。对中中新世（Langhian-Serravallian） Sidi Salim组近岸海洋环境进行了解释。中新世Qawasim组和上新世Kafr El Sheikh组为三角洲-浅海环境，上新世Abu Madi组为远海环境。Abu Madi组的这种较深的环境可以用来证实先前的文献，即上新世早期一个切口山谷的逐渐淹没，与迈西尼亚盐度危机（MSC）事件有关，该事件是由地中海迈西尼亚海平面下降引起的。在所研究的连续井沉积过程中存在亚氧至缺氧条件。在大部分井序列中发现了黄铁矿晶体的印记，证实了缺氧的存在。大量禾科花粉的出现可能表明该井新近纪沉积物沉积期间广泛存在干草地植被。在区域范围内，由于构造、古地理和盆地环境的影响，尼罗河三角洲地区的新近纪环境根据所调查沉积物的相对位置而变化。恢复的孢粉相在以无定形有机质（AOM）为主和以植物碎屑岩为主的类型之间波动，以干酪根ⅱ型为主，具有油气生产能力。对井段薄壁三棱孢子的孢子着色指数（SCI）的目视评价显示，其值在5 ~ 8之间，表明有机质热成熟，可能是潜在的烃源岩。
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Pub Date : 2025-06-02DOI: 10.1016/j.palwor.2025.200965
A. Sandersen , L. Scott , F.H. Neumann , E.W. Bergh , M. Bachari
Palynodebris in two cores from the western South African margin provides an opportunity for investigating stratigraphical changes across the Cretaceous/Paleogene (K/Pg) boundary and the depositional environments during this interval. Changing palynodebris trends of more than 200 sidewall cores and cuttings, sampled from two offshore ocean borehole sites ca. 243 km apart and situated in the Cape Basin, reflect the regional environmental processes during the Cretaceous and early Cenozoic. Thirteen categories of microscopic structures of palynomorphs and palynodebris (phytoclasts) are identified and recorded. These categories include amorphous organic matter, marine palynomorphs, fresh-water algae, resins, black debris (charcoal), yellow-brown fragments, black-brown fragments (including microscopic charcoal), cuticles, plant tissues, woody material, sporomorphs, and fungal material such as fungal spores, fruit bodies, tubes and filaments. The relative abundances of these organic components from each site were analyzed and compared. Palynodebris compositions and patterns differ between borehole sites over time but also show some similar regional trends, e.g., growing indications of burning from the Late Cretaceous to early Paleocene. The woody component suggests that both offshore sites received similar land-derived Cretaceous and Cenozoic sediments via fluvial transport. Palynodebris was compared to previously published palynological data from the cores, showing shifts in vegetation and climate. Around and shortly after the K/Pg boundary, black debris and yellow-brown debris components fluctuate strongly and could possibly be related more to the transition from the Maastrichtian regressive events than a terminal K/Pg boundary event. Stronger marine influence, as indicated by an increase of marine palynomorphs together with geological evidence of glauconitic sandstone, Inoceramus, other bivalves, and shelly material during the Late Cretaceous and Paleogene, reflects the flooding of the basin. The stratigraphy and depositional environments contribute to a better understanding of conditions associated with the opening of the South Atlantic Ocean.
{"title":"Cretaceous–Paleogene palynodebris from two offshore cores in Cape Basin, South Atlantic Ocean and their paleoenvironmental implications","authors":"A. Sandersen , L. Scott , F.H. Neumann , E.W. Bergh , M. Bachari","doi":"10.1016/j.palwor.2025.200965","DOIUrl":"10.1016/j.palwor.2025.200965","url":null,"abstract":"<div><div>Palynodebris in two cores from the western South African margin provides an opportunity for investigating stratigraphical changes across the Cretaceous/Paleogene (K/Pg) boundary and the depositional environments during this interval. Changing palynodebris trends of more than 200 sidewall cores and cuttings, sampled from two offshore ocean borehole sites ca. 243 km apart and situated in the Cape Basin, reflect the regional environmental processes during the Cretaceous and early Cenozoic. Thirteen categories of microscopic structures of palynomorphs and palynodebris (phytoclasts) are identified and recorded. These categories include amorphous organic matter, marine palynomorphs, fresh-water algae, resins, black debris (charcoal), yellow-brown fragments, black-brown fragments (including microscopic charcoal), cuticles, plant tissues, woody material, sporomorphs, and fungal material such as fungal spores, fruit bodies, tubes and filaments. The relative abundances of these organic components from each site were analyzed and compared. Palynodebris compositions and patterns differ between borehole sites over time but also show some similar regional trends, e.g., growing indications of burning from the Late Cretaceous to early Paleocene. The woody component suggests that both offshore sites received similar land-derived Cretaceous and Cenozoic sediments via fluvial transport. Palynodebris was compared to previously published palynological data from the cores, showing shifts in vegetation and climate. Around and shortly after the K/Pg boundary, black debris and yellow-brown debris components fluctuate strongly and could possibly be related more to the transition from the Maastrichtian regressive events than a terminal K/Pg boundary event. Stronger marine influence, as indicated by an increase of marine palynomorphs together with geological evidence of glauconitic sandstone, <em>Inoceramus</em>, other bivalves, and shelly material during the Late Cretaceous and Paleogene, reflects the flooding of the basin. The stratigraphy and depositional environments contribute to a better understanding of conditions associated with the opening of the South Atlantic Ocean.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"34 5","pages":"Article 200965"},"PeriodicalIF":1.7,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-26DOI: 10.1016/j.palwor.2025.200963
Yi-Nuo Wang , Da-Yong Jiang , Ryosuke Motani , Ming-Tao Yao , Min Zhou , Zuo-Yu Sun , Jian-Dong Huang , Zhao-Liang Ma
The emergence time of Mesozoic marine reptiles has been controversial due to poor stratigraphic control and the lack of radiometric age constraints. We report a radiometric age of 248.7 ± 1.0 Ma (2σ), obtained through LA-ICP-MS analysis of the zircon grains sampled from a tuff which is intercalated within the fossiliferous beds of the Chaohu Fauna and layered about 7 m above the lowest fossiliferous bed. This dating confirms the Chaohu Fauna as the oldest known marine reptile fauna in the world with precise and comprehensive age constraints. Integrated with the biostratigraphic data and astrochronological analysis, our results demonstrate that marine reptiles were established at least by 3.2 million years after the Permian–Triassic boundary.
中生代海生爬行动物的出现时间由于地层控制不佳和缺乏放射性年龄约束一直存在争议。通过LA-ICP-MS分析，我们获得了248.7±1.0 Ma （2σ）的放射性年龄，这些锆石颗粒来自于位于巢湖动物群化石层中，并在最低化石层之上约7 m处的凝灰岩。这证实了巢湖动物群是世界上已知最古老的海洋爬行动物群，具有精确和全面的年龄限制。结合生物地层资料和天体年代学分析，我们的研究结果表明，海洋爬行动物至少在二叠纪-三叠纪界线后320万年建立。
{"title":"Dating of Early Triassic Chaohu Fauna by precise U-Pb age constraints: Temporal calibration of the emergence and first radiation of Mesozoic marine reptiles","authors":"Yi-Nuo Wang , Da-Yong Jiang , Ryosuke Motani , Ming-Tao Yao , Min Zhou , Zuo-Yu Sun , Jian-Dong Huang , Zhao-Liang Ma","doi":"10.1016/j.palwor.2025.200963","DOIUrl":"10.1016/j.palwor.2025.200963","url":null,"abstract":"<div><div>The emergence time of Mesozoic marine reptiles has been controversial due to poor stratigraphic control and the lack of radiometric age constraints. We report a radiometric age of 248.7 ± 1.0 Ma (2σ), obtained through LA-ICP-MS analysis of the zircon grains sampled from a tuff which is intercalated within the fossiliferous beds of the Chaohu Fauna and layered about 7 m above the lowest fossiliferous bed. This dating confirms the Chaohu Fauna as the oldest known marine reptile fauna in the world with precise and comprehensive age constraints. Integrated with the biostratigraphic data and astrochronological analysis, our results demonstrate that marine reptiles were established at least by 3.2 million years after the Permian–Triassic boundary.</div></div>","PeriodicalId":48708,"journal":{"name":"Palaeoworld","volume":"34 5","pages":"Article 200963"},"PeriodicalIF":1.7,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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