Geobios最新文献

{"title":"Lower Ordovician Trilobites from SE Sardinia (Italy): A new record of the “Taihungshania bioprovince”","authors":"Gian Luigi Pillola ,&nbsp;Muriel Vidal","doi":"10.1016/j.geobios.2022.11.001","DOIUrl":"10.1016/j.geobios.2022.11.001","url":null,"abstract":"<div><p>A systematic description of the so far unique trilobite fauna and the associated biota from the Arenarie di San Vito Formation, in the outcrops close to the abandoned Tacconis mine (allochthonous nappe zone, Sarrabus, SE Sardinia, Italy), proves the occurrence of <em>Taihungshania shui landayranensis</em>, <em>Ampyx priscus</em>, <em>Asaphellus</em> sp., <em>Merlinia</em> sp., <em>Niobe fourneti?</em>, <em>Geragnostus</em> sp. and <em>Symphysurus</em> sp., accompanied by several taxa of graptolites, ichnofossils and less common bivalves, gastropods, cephalopods and hyolithids. The taphonomical signature, sedimentary structures and “Raphiophorid biofacies” clearly argue for an early Floian age and a median platform (i.e., offshore to shoreface) depositional environment. The occurrence of <em>T. shui landayranensis</em> in Sardinia allows us to determine the age of the Arenarie di San Vito Formation (just below the Sarrabese unconformity) and to discuss the palaeobiogeographical affinities highlighting the value of the “<em>Taihungshania</em> bioprovince”. The Tacconis trilobite fauna displays close affinities with Montagne Noire in France, Taurides in Turkey, Alborz in Iran, and south China, placing the SE Sardinia allochthonous area in a global Ordovician palaeogeographic sketch. A brief discussion on relationships and palaeobiogeographical affinities between the Sardinian nappe zone and the autochthonous “foreland” Sulcis-Iglesiente, which are adjacent today, strongly suggests a separation during the Ordovician, although both areas pertain to the Gondwana margin.</p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 67-84"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44016872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Skeletal elements controlled soft-tissue preservation in echinoderms from the Early Ordovician Fezouata Biota","authors":"Farid Saleh ,&nbsp;Bertrand Lefebvre ,&nbsp;Christophe Dupichaud ,&nbsp;Emmanuel L.O. Martin ,&nbsp;Martina Nohejlová ,&nbsp;Léa Spaccesi","doi":"10.1016/j.geobios.2023.08.001","DOIUrl":"10.1016/j.geobios.2023.08.001","url":null,"abstract":"<div><p>Exceptional fossils preserve non-biomineralized tissues in the geological record and provide crucial information on the evolution of life on Earth. Exceptionally preserved fossils are rarely discovered complete, challenging their morphological description and their palaeontological interpretation. Although decay experiments reconstructing degradation sequences in modern animals are necessary to better understand taphonomic processes involved in exceptional preservation, their applicability to some enigmatic and/or extinct fossil taxa remains limited. Here, based on a representative sample of 423 specimens collected from a single stratigraphic level from the Early Ordovician Fezouata Biota, we reconstruct the degradation sequence of both skeletal remains and soft tissues of stylophorans, an extinct clade of echinoderms. The rare preservation of the water vascular system can be explained by the rapid post-mortem opening of the cover plates resulting from the fast decay of associated muscles and the action of ligaments. In contrast, the proximal aulacophore and associated stylocone formed a particularly decay-resistant closed module, thus favouring the preferential preservation of included soft parts (fore-gut). The non-random location and frequency of pyritised intra-skeletal structures strongly suggest that skeletal elements dictated the preservation of underlying soft parts. As such, taphonomic investigations should not only focus on the environment surrounding a decaying animal, but also on the different environments created within a particular carcass.</p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 51-66"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0016699523001006/pdfft?md5=9f4ca9ae77a9348d9380a463ee641a98&pid=1-s2.0-S0016699523001006-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136117671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Filling knowledge gaps in the Ordovician radiations","authors":"Bertrand Lefebvre,&nbsp;Thomas Servais","doi":"10.1016/j.geobios.2023.10.001","DOIUrl":"10.1016/j.geobios.2023.10.001","url":null,"abstract":"","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 1-5"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135410781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Population dynamics of shoreface to upper offshore occupation of the lower Ordovician brachiopod Tarfaya purmamarcaensis (Benedetto)","authors":"Diego F. Muñoz ,&nbsp;Arnaud Bignon ,&nbsp;Juan Luis Benedetto","doi":"10.1016/j.geobios.2022.10.005","DOIUrl":"10.1016/j.geobios.2022.10.005","url":null,"abstract":"<div><p><span>Occupation of shallow environments by rhynchonelliform brachiopods is rare during the early late Tremadocian (Tr2). However, in the NW Argentina basin the plectorthoidean </span><em>Tarfaya purmamarcaensis</em> occupied high-energy environments during this time interval. This species forms up to 15 cm thick monospecific concentrations in shoreface and offshore transition settings, and polytypic pavements in relatively deeper water offshore environments. Generation of such concentrations could be linked to the population dynamics of <em>T. purmamarcaensis</em><span>. A geometric morphometrics analysis allowed us to recognize four growth stages in the ontogeny of the species. The juvenile phases are absent in high-energy proximal environments and are scarce in the shoreface; in contrast, no representatives of the fourth phase (hypermature adults) have been found in the open platform deposits, and adults are almost absent. Although shell concentrations are usually linked to physical processes (i.e., storm events), the low taphonomic alteration of the shells suggests that transport was not a highly influential factor. Morphological differences (i.e., development of cardinal canals, ribs incurved posterolaterally) in specimens from different environments suggest that the population dynamics could have been the main cause in generating different concentrations. According to the source-sink model, high productivity of brachiopods in the shoreface environment and a passive transport of larvae to the offshore might explain not only the thicker shallow-water concentrations but also the differences in shell growth of populations inhabiting these environments.</span></p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 17-29"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47593128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Yuexiconcha nov. gen. – A resilifer-bearing palaeotaxodont (Bivalvia, Protobranchia) from the Ordovician of Guangdong, South China","authors":"Niu Zhi-jun ,&nbsp;Zhang Ren-jie ,&nbsp;Paul A. Johnston ,&nbsp;Li Chu-an ,&nbsp;Wang Zhi-hong ,&nbsp;Hu Kun ,&nbsp;Song Fang ,&nbsp;He Yao-yan ,&nbsp;He Jin-lan ,&nbsp;Lin Xiao-ming ,&nbsp;Yang Wen-qiang","doi":"10.1016/j.geobios.2023.01.006","DOIUrl":"10.1016/j.geobios.2023.01.006","url":null,"abstract":"<div><p>A unique, new palaeotaxodont (Protobranchia) genus and species, <em>Yuexiconcha duplicata</em><span> Zhang, Niu and Johnston, is proposed and described. It is characterized by: a medium-sized, transversely elongated, sub-elliptical shell; heterotaxodont dentition; and posterior tooth row consisting of crowded gradidentate dentition, partially and dorsally overlapped by an additional tooth row that emanates from the beak to form a bitaxodont dentition (new term). Most significantly, a prominent resilifer separates the anterior and posterior tooth rows and shows slight to moderate excavation into the hinge-plate. While a resilifer indicates phylogenetic proximity with </span><em>Nuculoidea</em>, <em>Yuexiconcha</em> nov. gen. is readily distinguished by its bitaxodont posterior dentition and a more elongate posterior shell lobe and so is provisionally placed in the Family Nuculidae, Order Nuculida. The hinge of <em>Yuexiconcha</em><span><span> nov. gen. indicates that a resilifer in palaeotaxodonts first developed in the Ordovician<span>, rather than in the Silurian (Wenlock) as thought previously. Specimens described herein were collected from a fine-grained siliciclastic rock unit in the upper part of the Dongchong Formation in western Guangdong, South China. Other components of the biota occurring with the bivalves are uncommon and include trilobites and brachiopods that indicate a late Middle–early </span></span>Late Ordovician (late Darriwilian–early Sandbian) age.</span></p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 121-134"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48351961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Middle Ordovician brachiopods from Tagoat, Co. Wexford, SE Ireland: Dapingian diversity drivers","authors":"David A.T. Harper ,&nbsp;Denis E.B. Bates","doi":"10.1016/j.geobios.2023.06.006","DOIUrl":"10.1016/j.geobios.2023.06.006","url":null,"abstract":"<div><p>The Dapingian (Arenig) siltstones and sandstones of the Tagoat Group, County Wexford, SE Ireland, contain a well-preserved and diverse brachiopod fauna including a new genus of alimbellid, <em>Palaeotagoatia</em> (type species: <em>Orthis Bailyana</em> Davidson) together with the plectorthid <em>Ffynnonia costata</em> (Bates) <em>hibernica</em> nov. subsp. Of the 13 forms documented, at least six are conspecific with brachiopods from the upper Arenig (Dapingian-lowest Darriwilian) Treiorwerth Formation on Anglesey and a further two are identified with species occurring in the older Dapingian Carmel Formation. The faunal province affinities of the fauna are with those assemblages assigned to the peri-insular and marginal Celtic province and which occupied positions within the Middle Ordovician Iapetus Ocean between the Laurentian and Baltic platform provinces. More precise correlation of Middle Ordovician units suggests a significant species richness during the Dapingian-earliest Darriwilian and signalling also an early development of the Celtic province. But the shallow-water siliciclastic facies associated with these islands may also have influenced the distribution of some elements of the Celtic brachiopods and promoted the prevalence of coarse-ribbed orthides, such as <em>Paralenorthis</em>.</p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 85-100"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0016699523000712/pdfft?md5=049b0ace6e7ed388c0439e0c57c1ab7a&pid=1-s2.0-S0016699523000712-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48933278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Latest Ordovician jawed polychaetes, chitinozoans and depositional environments of the Levín section, Prague Basin, Czech Republic","authors":"Petra Tonarová ,&nbsp;Stanislava Vodrážková ,&nbsp;Olle Hints ,&nbsp;Jaak Nõlvak ,&nbsp;Michal Kubajko ,&nbsp;Pavel Čáp","doi":"10.1016/j.geobios.2023.01.008","DOIUrl":"10.1016/j.geobios.2023.01.008","url":null,"abstract":"<div><p>Jawed polychaetes evolved and diversified extensively during the Ordovician. However, Ordovician polychaete jaws (scolecodonts) have remained poorly documented for many regions. This applies for the Prague Basin of peri-Gondwana, from where the previous study on Late Ordovician scolecodonts was published more than 70 years ago, with just two species preliminarily identified. The aim of the present paper was to fill this research gap and to study organic-walled microfossils from the boundary interval of the Králův Dvůr and Kosov formations (uppermost Katian and lowermost Hirnantian) at the Levín locality. As a result, a diverse assemblage of scolecodonts and chitinozoans was discovered. Chitinozoans are represented by at least 24 species from 15 genera, i.e., a relatively diverse assemblage whose species composition points toward the <em>Ancyrochitina merga</em> and <em>Tanuchitina elongata</em><span> biozones. The recovered jawed polychaete fauna contains at least 19 species from 14 genera. Taxa with labidognath and prionognath type maxillary apparatuses predominate in samples, whereas placognath and ctenognath taxa are relatively rare. A similar pattern is typical for the Laurentian samples but contrasts with the Baltic polychaete faunas. Polychaetaspids dominate in the Levín assemblage, followed by other families such as ramphoprionids, paulinitids, and atraktoprionids. The studied interval in the Levín section is represented by a succession of thin-bedded silty shales with diamictite beds, practically devoid of shelly fossils and with a variable degree of bioturbation. The deposits are interpreted as distal turbidites and debrites, reflecting sea-level changes driven by the growth and retreat of glacial ice and possibly also local tectonics. Reduced diversity and abundance of scolecodonts was recorded in the uppermost part of the Králův Dvůr Formation, which correlates with less bioturbation and finer silt fraction. The reported discovery shows wide geographical distribution and diversity of jawed polychaetes before and during the Hirnantian glaciation and mass extinction.</span></p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 179-198"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47336066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Babies from the Fezouata Biota: Early developmental trilobite stages and their adaptation to high latitudes","authors":"Lukáš Laibl ,&nbsp;Harriet B. Drage ,&nbsp;Francesc Pérez-Peris ,&nbsp;Sebastian Schöder ,&nbsp;Farid Saleh ,&nbsp;Allison C. Daley","doi":"10.1016/j.geobios.2023.06.005","DOIUrl":"10.1016/j.geobios.2023.06.005","url":null,"abstract":"<div><p><span>The Lower Ordovician<span> Fezouata Shale is renowned for its exceptionally-preserved euarthropod fossils<span> including numerous species of trilobites, some of which show remains of appendages and traces of the digestive system. Herein, we describe the early developmental stages of at least nine trilobite species from the Tremadocian strata of the Fezouata Shale, namely </span></span></span><em>Platypeltoides magrebiensis</em>, <em>Nileus deynouxi</em>, <em>Symphysurus ebbestadi</em>, <em>Asaphellus</em> sp., <em>Megistaspis</em> (<em>Ekeraspis</em>) <em>hammondi</em>, <em>Orometopus</em> sp., <em>Anacheirurus adserai</em>, <em>Bavarilla zemmourensis</em>, <em>Indiligens</em><span> sp., and several specimens of undetermined protaspides. This study considerably expands our knowledge of the development of early Ordovician trilobites. The preservation of appendages in the early stages of </span><em>N. deynouxi</em> and <em>S. ebbestadi</em>, and remains of the digestive tract in the latter species, suggests that some immature trilobites had similar morphology and anatomy as the adult individuals. Early developmental stages of <em>Indiligens</em> sp. might have fed and/or hidden on graptolites and demosponges. The extraordinarily large size of the early post-embryonic stages of <em>P</em>. <em>magrebiensis</em>, <em>S</em>. <em>ebbestadi</em>, <em>Orometopus</em> sp., <em>Asaphellus</em><span> sp., and undetermined protaspides suggests that these trilobites might have hatched from yolk-rich eggs. The presence of several trilobite species with notably large post-embryonic stages in the Fezouata Shale might be explained by seasonal or low productivity in the high-latitude margin of Gondwana.</span></p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 31-50"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46333617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new pustulose bivalve from the Late Ordovician of the Prague Basin (Czech Republic) and remarks on the diversification of pteriomorphids","authors":"Marika Polechová ,&nbsp;Ondřej Zicha ,&nbsp;Štěpán Rak","doi":"10.1016/j.geobios.2023.04.001","DOIUrl":"10.1016/j.geobios.2023.04.001","url":null,"abstract":"<div><p><span>The new genus </span><em>Alena</em> Polechová, Zicha and Rak, with its type species <em>Alena pustulosa</em><span> nov. gen., nov. sp., is described from the Sandbian Letná Formation of the Prague Basin (Czech Republic) as a new Late Ordovician bivalve with pustules. </span><em>Alena pustulosa</em><span> nov. gen., nov. sp. appears to be an endobyssate bivalve based on its functional morphology. It is placed within Cyrtodontida (Pteriomorphia) and included in the diversified </span><em>Modiolopsis draboviensis</em><span><span> Association from the Letná Formation, which comprises eleven bivalve species. The bivalve association from the Letná Formation is formed predominantly by pteriomorphids (now six species out of eleven) and shows that pteriomorphian groups also radiated strongly in shallow-water sands and silts in mid-latitude areas. All main groups of Pteriomorphia are already known from the Early Ordovician and diversified rapidly during the Ordovician. The </span>Gondwana<span> and peri-Gondwana margins with two Early Ordovician radiation centers (Central Australia and Northwestern Argentina) played important roles in their early diversification and dispersion to other palaeocontinents. The function of the sculpture in bivalves is discussed with an emphasis on the Ordovician bivalves. The ornamentation in bivalves serves several purposes such as supporting the stable position of the shell in a substrate, helping in burrowing, strengthening of shell, and protecting against predators. In the Ordovician bivalves, the main function of the sculpture is to stabilise the shell in the substrate.</span></span></p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 135-143"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48911006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tremadocian (Ordovician) trilobites from the Brabant Massif (Belgium): Palaeogeographical and palaeoecological implications","authors":"Lukáš Laibl ,&nbsp;Thomas Servais ,&nbsp;Bernard Mottequin","doi":"10.1016/j.geobios.2023.04.003","DOIUrl":"10.1016/j.geobios.2023.04.003","url":null,"abstract":"<div><p><span>A poorly diverse trilobite assemblage is described from the Tremadocian strata (Tangissart Member of the Mousty Formation; Chevlipont Formation) of the Brabant Massif. These specimens represent so far the oldest trilobite record from Belgium. The recorded taxa, identified as </span><em>Platypeltoides</em> cf. <em>croftii</em>, <em>Macropyge</em><span><span>? sp., and Asaphidae indet., resemble contemporaneous trilobites from other parts of Avalonia<span> (e.g., Wales, Shropshire) as well as some others from high-latitude </span></span>Gondwana (Morocco). The nileid species </span><em>P</em>. cf. <em>croftii</em> suggests that the Tangissart Member of the Mousty Formation was likely deposited in deeper offshore environments on the open shelf of Avalonia. Morphological similarities between <em>P</em>. cf. <em>croftii</em> from the Brabant Massif, <em>P</em>. <em>croftii</em> from the UK, and <em>P</em>. <em>magrebiensis</em> from Morocco suggest close faunal interchange across the narrow Rheic Ocean.</p></div>","PeriodicalId":55116,"journal":{"name":"Geobios","volume":"81 ","pages":"Pages 7-16"},"PeriodicalIF":1.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47863685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}