Article
Geography, Physical
Chengsheng Jin, Zhiwei Liao, Gary G. Lash
Summary: The study suggests that fluctuations in redox conditions, in addition to commonly cited thresholds of bimetal ratios, may have influenced the redox trends during the Ordovician-Silurian transitional interval. The strong correlation between changing redox conditions and fossil distributions implies that dynamic and ferruginous conditions contributed to biotic crises. The coupling of total organic carbon (TOC) and redox proxies highlights the importance of prolonged anoxia or euxinia in the accumulation and preservation of organic matter.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Clinton Barineau, Douglas A. Sagul, Paul A. Mueller
Summary: In the southern Appalachian region, it is recognized that Ordovician and Silurian siliciclastic, volcanic, and plutonic rocks are part of a paired arc/back-arc system that formed on the seaward edge of the Laurentian plate. New crystallization ages confirm rapid deposition in an Ordovician-Silurian extensional basin that received input from continentally derived Mesoproterozoic crust and bimodal volcanic components. The ages of zircons suggest a significant Mesoproterozoic component in the genesis of these rocks.
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
(2022)
Article
Geosciences, Multidisciplinary
Amine Cherif, Madani Benyoucef, Mohammed Nadir Naimi, Bruno Ferre, Ahmed Zeghari, Camille Frau, Ali Berrabah
Summary: The study explores the lithostratigraphic units and ichnofacies characteristics of the Berriasian-Valanginian succession in northwestern Algeria, showcasing nine ichnotaxa for the first time in the early Cretaceous of Algeria. This ichno-association suggests a deepening environment from the platform to the basin as seen in previous studies in the Mediterranean region during the same time interval.
JOURNAL OF AFRICAN EARTH SCIENCES
(2021)
Article
Geography, Physical
Xiangrong Yang, Detian Yan, Daizhao Chen, Mu Liu, Xiaohui She, Bao Zhang, Liwei Zhang, Junfeng Zhang
Summary: The measurement of carbon and nitrogen isotopes in marine sediments from the late Ordovician to the early Silurian on the Yangtze Platform suggests that nitrate limitation in offshore environments may have restricted the distribution of eukaryotes, impacting the late Ordovician extinction and early Silurian biotic recovery. The global variation in delta C-13(org) values during the late Ordovician may have been related to nitrate availability, affecting productivity and potentially enhancing carbon cycling gradients on shelves globally.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2021)
Article
Geology
Zhen Qiu, Yifan Li, Wei Xiong, Tailiang Fan, Qun Zhao, Qin Zhang, Yuman Wang, Wen Liu, Feng Liang, Jiaqiang Zhang, Gary Lash
Summary: This study reevaluates how regional and global events influenced the paleoenvironmental evolution of the Upper Yangtze Block. The results indicate frequent fluctuations of redox conditions during the Late Katian time, which are related to eustatic sea-level changes. The relationships between lithofacies and organic carbon content suggest weak to moderate restriction in the Upper Yangtze Shelf Sea.
SEDIMENTARY GEOLOGY
(2023)
Article
Geography, Physical
Guangyao Cao, Yu Liu, Chao Li, Ping'an Peng, Mingcai Hou, Gary G. Lash, Xiaolin Zhou, Yuanchun Li, Ying Song
Summary: The Ordovician-Silurian transition is a critical geological period marked by significant climatic, environmental, and biological changes. This study examines the paleosalinity conditions of the inner Yangtze Sea during this period and finds that salinity variations are influenced by climate changes, particularly lower salinity during glacial intervals. These salinity perturbations are also linked to the development of euxinia in the inner Yangtze Sea, highlighting the importance of seawater salinity in driving evolutionary patterns during this critical period in Earth history.
GLOBAL AND PLANETARY CHANGE
(2023)
Article
Geosciences, Multidisciplinary
Walid A. Makled, Sherif Farouk, Aboosh Hussain Al-Hadidy, Ibrahim Q. Mohammed, Fadhil Ahmed Ameen Lawa
Summary: The Ordovician-Silurian hot shales in the Akkas Field are proven to be a source of hydrocarbon, with potential for liquid hydrocarbon generation. The study reveals the first record of important oil-prone organic matter in the region, with evidence of seasonal changes and evolution of telalginite particles.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Xiaolin Zhou, Yu Liu, Haiyang Cao, Hanting Zhong, Yuanchun Li
Summary: This study investigates the geochemical composition of sediments in the Ordovician-Silurian transition on the Yangtze Platform, highlighting the impact of diagenesis on Fe speciation and its implications for organic accumulation. The findings suggest that productivity, upwelling, and climatic conditions play a significant role in organic accumulation in different periods, emphasizing the importance of a multi-proxy approach in paleoenvironmental studies.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Geology
Russell D. C. Bicknell, Javier Ortega-Hernandez, Gregory D. Edgecombe, Robert R. Gaines, John R. Paterson
Summary: This study describes a well-preserved central nervous system in the horseshoe crab Euproops danae from the late Carboniferous Mazon Creek Konservat-Lagerstatte, demonstrating that the organization of prosomal synganglion has remained stable for over 300 million years and suggesting the potential for further preservation examples in the Mazon Creek fauna. This discovery fills a significant temporal gap in the fossil record of euarthropod CNSs and expands the taphonomic scope for preservation of detailed paleoneuroanatomical data in the Paleozoic to siderite concretion Lagerstatten of marginal marine deposits.
Article
Geography, Physical
Gabriel Teofilo Guedes Silva, Diego Luciano Nascimento, Alessandro Batezelli, Francisco Sergio Bernardes Ladeira, Marcio Luiz Silva
Summary: Burrowing behavior is an important adaptation for animals in arid conditions. This paper describes turtle burrows from the Upper Cretaceous period in the Bauru Basin, Brazil. The burrows were preserved in fluvial sandstone and showed a J-shaped tunnel structure. Based on their morphology and features, it is suggested that these burrows were formed by turtles during aestivation.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2022)
Article
Geology
Andrea Baucon, Carlos Neto de Carvalho, Fabrizio Felletti, Gabriele Tosadori, Alexandre Antonelli
Summary: The study reveals that burrow morphologies show persistent patterns over evolutionary time scales, influenced by small-world dynamics and forming associations between shallow and deep-sea burrows. This pattern follows assembly rules similar to those shaping human social networks.
Article
Geology
Eduardo Mayoral, Jorge F. Genise, Francisco J. Rodriguez-Tovar, Ana Santos
Summary: This study in the Lepe area of Spain found two different types of trace-compatible cells that were coeval with the trace-bearing rocks, contrasting with the usual asynchronies found in Paleozoic and Mesozoic rocks. The short time gap between the rocks and the traces enhances their potential coevalness, serving as a warning for potential examples of relatively short asynchronies in the fossil record.
Article
Multidisciplinary Sciences
Stefan Bengtson, Birger Rasmussen, Jian-Wei Zi, Ian R. Fletcher, James G. Gehling, Bruce Runnegar
Summary: Researchers have found that the animal burrows in the Paleoproterozoic metasedimentary rocks of the Mount Barren Group in southwestern Australia may predate the last metamorphic event in the region and were formed during an Eocene transgression. After this event, there was resilicification of the quartzites, filling the pore space with syntaxial quartz cement forming silcretes, making the rocks hard again and impenetrable to animal burrowing.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Paleontology
Jaroslav Samanek, Lothar H. Vallon, Radek Mikulas, Michal Vachek
Summary: The old brickyard Velka nad Velickou in the Czech Republic provides a unique insight into a Eocene deep-sea ichno-assemblage dominated by sequestrichnia. The tracemaker Chondrites intricatus is seen frequently penetrating the Zoophycos brianteus trace fossil and occurring preferentially on the surface of Zoophycos spreiten, indicating the secondary use of food-stowing. This close relationship between Chondrites and Zoophycos supports the hypothesis of sequestrichnial behavior of Zoophycos producer. Other fossils such as Helminthopsis tenuis, Tubulichnium mediterranensis, Scolicia strozzii, ?Dactyloidites isp., Megagrapton irregulare, and Planolites isp. are also found in this studied locality.
ACTA PALAEONTOLOGICA POLONICA
(2022)
Article
Multidisciplinary Sciences
Xianqing Jing, Zhenyu Yang, Ross N. Mitchell, Yabo Tong, Min Zhu, Bo Wan
Summary: This study reports a large and fast true polar wander event that occurred 450-440 million years ago and provides evidence based on paleomagnetic data and paleopoles from major continents. The study also suggests that this event can explain the migration of glacial centers and the mass extinction at the end of the Ordovician period.
NATURE COMMUNICATIONS
(2022)
Article
Paleontology
Olev Vinn, Anna Madison, Mark A. Wilson, Ursula Toom
Summary: This study describes seven species of cornulitids, an unidentified tubicolous shell, and a problematic bryozoan from the Katian of Baltica. It reveals that the diversity and number of cornulitids in the Ordovician of Baltica were underestimated, with intermediate forms indicating ancestral traits inherited by tentaculitids. The clay mud-bottom environments in Late Ordovician Baltica supported the highest cornulitid diversity.
JOURNAL OF PALEONTOLOGY
(2023)
Article
Biodiversity Conservation
Olev Vinn, Bert W. W. Hoeksema, Boguslaw Kolodziej, Zuzana Kozlova
Summary: Reefal limestones of the Stramberk Carbonate Platform, preserved in deep-water flysch of the Outer Carpathians, contain rich coral assemblages of the Jurassic/Cretaceous transition. Symbiotic associations between corals and tube-dwelling macroorganisms were observed in Calamophylliopsis flabellum and Calamophylliopsis sp. Two types of tubes were recognized, likely produced by serpulids or organic-walled sabellid polychaete worms. This association represents possibly the oldest record of a sabellid-coral association, with indications of mutualistic or commensal symbiosis.
Article
Paleontology
Steven J. Hageman, Olev Vinn
Summary: The phylum Bryozoa, a major animal group, was thought to be absent from the Cambrian period until the discovery of Pywackia baileyi, which is now recognized as the oldest known bryozoan. Controversy exists regarding its taxonomic identification, with some suggesting it may be an octocoral. However, analysis of its skeletal microstructure suggests a closer affinity to cnidarians.
JOURNAL OF PALEONTOLOGY
(2023)
Article
Paleontology
Vishal Verma, Birendra P. Singh, Om N. Bhargava, Ravi S. Chaubey, Radek Mikulas, Olev Vinn, Subhay K. Prasad, Scott Morrison, Deepak Kumar
Summary: Abundant Psammichnites traces were preserved in the Kunzam La Formation in the Tethyan Himalaya region of southern China. A study of a well-dated Cambrian section in the Zanskar region identified three zones of Psammichnites, with Psammichnites gigas circularis dominating in the lowermost rocks, followed by Psammichnites gigas gigas and a overlap with Psammichnites gigas arcuatus in the upper part. The biostratigraphic correlation of Psammichnites indicates its usefulness in correlating rocks of the same age in the Tethyan Himalayan sections.
NEUES JAHRBUCH FUR GEOLOGIE UND PALAONTOLOGIE-ABHANDLUNGEN
(2023)
Article
Geography, Physical
Olev Vinn, Mark A. Wilson, Andrej Ernst
Summary: Trepostome bryozoans formed the largest number of symbiotic associations with endobionts in the Phanerozoic, and such associations were also formed by other bryozoans and cyclostomes. Most of the associations were with cnidarians, while fewer were with worms and lophophorates. The evolution of symbiotic relationships and the decrease in parasitic associations in bryozoans can be attributed to their selective behavior and the development of defense mechanisms.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2023)
Article
Geology
Olev Vinn, Lars E. Holmer, Mark A. Wilson, Mare Isakar, Ursula Toom
Summary: A steinkern of an endoceratid nautiloid siphuncle contains a Trypanites sozialis boring with a lingulate brachiopod Rowellella sp. shell inside. The formation of the lithified steinkern might have occurred partly in the seawater or after exhumation, which allowed colonization by boring organisms. This bioerosion resulted in numerous Trypanites borings in the siphuncle. The vacant boring was later colonized by a small lingulate brachiopod, which was preadapted to life in hard substrate borings and benefited from increased availability and predation pressure during the Late Ordovician GOBE.
Article
Biology
Olev Vinn, Lars E. E. Holmer, Mark A. A. Wilson
Summary: The evolution of brachiopod symbiosis is closely related to the evolution of brachiopod faunas and their partner groups in the early Palaeozoic era. The number of symbiotic associations varied with the number of taxa in brachiopod groups, and there was no particular group that had a higher tendency for symbiosis. Symbiotic associations first appeared after the emergence of certain brachiopod groups, with Cambrian brachiopods forming partnerships with typical Cambrian fauna. Bryozoans and tentaculitoid tubeworms, important partners during the Ordovician and Silurian, diversified in the Ordovician. The decrease in the number of brachiopod partner groups from the Cambrian to the Silurian was likely due to specialization, but the number of symbiotic associations did not increase faster than the number of brachiopod taxa. The GOBE-induced diversification of brachiopod taxa did not lead to an escalation in symbiotic relationships. Symbiotic associations involving brachiopods continued after the end-Ordovician mass extinction. Early Palaeozoic brachiopods were vulnerable to kleptoparasites, but the harm caused by these parasites was not sufficient to drive their associated brachiopods to extinction.
HISTORICAL BIOLOGY
(2023)
Article
Paleontology
Olev Vinn, Ursula Toom
Summary: The first Oikobesalon burrow from the Upper Ordovician of Russia is described. It closely resembles O. coricaceum specimens from the Darriwilian of Estonia. The earliest records of O. coricaceum are from Baltica and have a temperate climate association, while Silurian records are associated with tropical climate. The trace makers of O. coricaceum in the Sandbian of Russia lived in a temperate sea. The trace makers of Oikobesalon tolerated different sedimentary environments in the Ordovician.
NEUES JAHRBUCH FUR GEOLOGIE UND PALAONTOLOGIE-ABHANDLUNGEN
(2023)
Article
Geology
Rachid Khalili, Olev Vinn
Summary: This study describes the discovery of a vermetid etching trace from the Lower Chelif Basin, Algeria. It is the first record of such etchings from the Pliocene of the southern coast of the Mediterranean Sea. The study also suggests that vermetids were common in the Mediterranean region during the Pliocene.
PROCEEDINGS OF THE GEOLOGISTS ASSOCIATION
(2023)
Article
Geology
Olev Vinn, Ravi S. Chaubey, Birendra P. Singh, Om N. Bhargava, Subhay K. Prasad
Summary: Limestones of the Takche Formation in the Himalayas are characterized by Late Ordovician marine fauna and flora, with an abundance of dasyclad green algae indicating a warm climate.
PROCEEDINGS OF THE GEOLOGISTS ASSOCIATION
(2023)
Article
Geology
Olev Vinn, Boguslaw Kolodziej, Zuzana Kozlova
Summary: The described fossils are short tubes from the Stramberk Limestone in the Czech Republic, composed of single valves. The tubes resemble oysters due to their tube-like morphology and the shapes of their lamellae and tabulae. Therefore, the Stramberk tubes are inferred to represent oysters or oyster-related bivalves.
CARNETS DE GEOLOGIE
(2023)
Article
Paleontology
Ravi S. Chaubey, Birendra P. Singh, Olev Vinn, Om N. Bhargava, Subhay K. Prasad, Madhusudan Sati
Summary: An integrated litho-microfacies and sequence stratigraphic analysis was conducted on the Takche Formation (Ordovician-Silurian) in the Pin Valley, Spiti region. Ten lithofacies were identified, indicating deposition in a shallow marine carbonate ramp with highly fluctuating energetic conditions. The sequence stratigraphic analysis revealed three sequences, two maximum flooding surfaces, and five upward shoaling cycles, suggesting transgressive and regressive events. The presence of three disconformity surfaces resulted from submarine erosion or rapid fall in relative sea-levels.
NEUES JAHRBUCH FUR GEOLOGIE UND PALAONTOLOGIE-ABHANDLUNGEN
(2023)
Article
Paleontology
Olev Vinn, Andrej Ernst, Mark A. Wilson, Oive Tinn, Mare Isakar, Ursula Toom
Summary: Valves of the Sowerbyella tenera brachiopod in lower Katian, Estonia, are often encrusted by trepostome bryozoan colonies. In some cases, the encrustation likely occurred while Sowerbyella was alive. A single Sowerbyella tenera specimen contains three post-mortem borings by Palaeosabella prisca, within the interface between the encrusting trepostome colony and the ventral valve. The encrusting trepostome colonies include Anoigmaichnus-like, Kuckerichnus-like bioclaustrations, A. zapalskii, A. bretti, and a symbiotic conulariid. The bioclaustrated organisms and the conulariid colonized living bryozoans.
NEUES JAHRBUCH FUR GEOLOGIE UND PALAONTOLOGIE-ABHANDLUNGEN
(2023)
Article
Geosciences, Multidisciplinary
Abdelfattah Azizi, Asmaa El Bakhouch, Abderrazak El Albani, Kalle Kirsimae, Mouhssin El Halim, Khadija El Hariri, Mohamed Erragragui, Ahmid Hafid, Olev Vinn
Summary: This article focuses on the stratigraphic position of the Ediacaran-Cambrian boundary in Morocco's Anti-Atlas Mountains. While no trace fossils or body fossils were found previously, abundant trace fossils were discovered at the base of the Adoudou Formation, providing evidence for the boundary's location through the integration of carbon isotope records.
PRECAMBRIAN RESEARCH
(2023)
Article
Geology
Abdelfattah Azizi, Abderrazak El Albani, Khadija El Hariri, Asmaa El Bakhouch, Olev Vinn, Ahmid Hafid, Kalle Kirsimaee
Summary: The Igoudine and Amouslek formations in the western Anti-Atlas of Morocco provide insights into the replacement of microbial consortia and the paleoredox conditions during the Terreneuvian-Cambrian Epoch 2 boundary. Geochemical analysis suggests that the terrigenous fraction in these formations likely originated from felsic rocks and the sediments were deposited in an oxic environment. The transition from stromatolite-dominated biota to thrombolite-archaeocyathan consortium and shelly metazoans was not driven by seawater redox status.
ESTONIAN JOURNAL OF EARTH SCIENCES
(2023)
