Evolving Earth最新文献

{"title":"Mid-to late Holocene vegetation and environmental change at local and regional scales based on a multi-proxy analysis of the upper Danube Delta, Romania","authors":"Diana Hanganu ,&nbsp;Alfred Vespremeanu-Stroe ,&nbsp;Angelica Feurdean ,&nbsp;Antony Gavin Brown ,&nbsp;Laurențiu Țuțuianu ,&nbsp;Sabin Rotaru ,&nbsp;Gabriela Sava","doi":"10.1016/j.eve.2023.100008","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100008","url":null,"abstract":"<div><p>The Danube Delta is Europe's largest wetland system and of unique biogeographical character. Whilst its geomorphological evolution is relatively well-known its ecological history is poorly understood, including the history of human impact, as a result of the dynamic nature of deltaic systems, and the scarcity of reliably dated successions. In this paper, we report a multi-proxy record of palynology, sediment texture, geochemistry, and ostracods from the upper reaches of the Danube Delta. We use these data to reconstruct a mid-to-late Holocene history of vegetation and environmental changes at local and regional scales, which serve as a model for understanding baseline conditions in delta apex regions. From 7500 to 6200 ​cal ​yr BP, the study site was part of an inter-distributary channel-levee system connected to coastal lagoons and sensitive to sea-level fluctuations but transitioned to a partially-disconnected lacustrine environment after 5700 ​cal ​yr BP. These geomorphologically-driven landscape changes strongly influenced the pollen source area making it complex to interpret palynoassemblages. Prior to 5700 ​cal ​yr BP, palynoassemblages were predominantly river-transported, reflecting widespread hinterlands, and providing information for the regional reconstruction of the vegetation history in the northern Dobrogea region. These data reveal the early presence of <em>Carpinus</em> and <em>Fagus</em> in southeastern Romania, prior to their spread through the Carpathian Basin. After 5700 ​cal ​yr BP, initiated by a slowdown in the relative rate of rise of the Black Sea, peat accumulation commenced within the shallow lake depocentre and airborne pollen became the dominant source. These pollen data record an expansion of herbaceous taxa and highly diverse marsh and aquatic taxa. Tree cover became dominated by <em>Quercus</em>, with low percentages of <em>Carpinus, Betula, Ulmus,</em> and <em>Tilia.</em> The earliest pollen evidence indicative of human impact commences c. 6500 ​cal ​yr BP) and, after 3200 ​cal ​yr BP, the decline in <em>Quercus</em> and a synchronous rise in archaeological artifacts, points to an opening of the landscape by forest clearance and an enlargement of arable areas. In particular, clearance and agriculture during the development of the Hallstattian Babadag culture (c. 3200-2800 ​yr BP) reflects an increase in population and settlement density during that late interval. Our paper comprises the first mid-to-late Holocene palynological record for the Danube Delta and highlights how human activity has profoundly altered the dryland region, creating landscapes comparable to today from around 3200 years BP, while the local deltaic landscape retained its character over the last six millennia.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100008"},"PeriodicalIF":0.0,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative taphonomy of Kem Kem Group (Cretaceous) pterosaurs of southeast Morocco","authors":"Roy E. Smith ,&nbsp;David M. Martill ,&nbsp;Nick Longrich ,&nbsp;David M. Unwin ,&nbsp;Nizar Ibrahim ,&nbsp;Samir Zouhri","doi":"10.1016/j.eve.2023.100006","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100006","url":null,"abstract":"<div><p>Although diverse, disparate, widespread, and long-lived, our understanding of pterosaurs is heavily biased by specimens from Konservat-Lagerstätten. Here we consider the pterosaur assemblage of the mid-Cretaceous Kem Kem Group of southeast Morocco and compare its taphonomy to other Cretaceous pterosaur-bearing assemblages. The Kem Kem Group pterosaur bones are usually fragmentary and isolated but preserved three-dimensionally, with excellent preservation of macroscopic internal structures and bone histology at ultrastructural levels. The pterosaur assemblage is dominated by azhdarchoid jaw fragments, all anterior of the nasoantorbital fenestra and divergence of the mandibular rami. Post-cranial elements are much rarer with a striking lack of syncarpals, despite being some of the most robust elements of the skeleton. Comparisons with similar deposits in the United Kingdom, Uzbekistan and USA suggest that this relative skeletal abundance is unusual for pterosaur assemblages. The overabundance of jaw material in the Kem Kem Group is likely the result of a combination of factors including the inherent mechanical strength of the jaws, selective predation and scavenging and transportation/hydrodynamic sorting of some elements. The Kem Kem Group should be considered a Konzentrat-Lagerstätte due to the high abundance of vertebrate material. Despite the fragmentary nature of the material, it has excellent preservation of internal structures at macroscopic and microscopic scales. The Kem Kem Group pterosaur assemblage is among the most species diverse known, but taphonomic processes and biases likely obscure its true diversity.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100006"},"PeriodicalIF":0.0,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecological polarities of African Miocene apes","authors":"Gregory J. Retallack","doi":"10.1016/j.eve.2023.100005","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100005","url":null,"abstract":"<div><p>Humans have been considered ecologically unspecialized, and our evolution a compromise path through a maze of conflicting influences. Generalist ecological roles contrast with ecological polarities such as competitor, breeder or tolerator. Ecological polarities can be approximated in fossil mammals by relative size of canines for competitors, incisors for breeders, and molars for tolerators. Considered in this way, early Miocene apes of Kenya were generalists, but show a greater range of ecological polarity than modern apes, including ecological polarities found in living apes, macaques, and vervets. As many as six primates in a single Miocene aleosol show diverse ecological polarities, implying competitive exclusion. Middle Miocene monkeys and apes were more molarized and marginally more tolerant than early Miocene primates, so more like humans in that respect. This adaptive shift of 15 ​Ma was at a time of climatic aridity and open vegetation indicated by associated paleosols. A 20 ​m.yr record of Kenyan paleoprecipitation from paleosols indicates that 15 ​Ma was unusually dry after exceptionally wet paleoclimate of 16 ​Ma. This new Kenyan paleosol record of paleoclimate is from the same localities as the fossil apes, and uninfluenced by whole ocean mixing, salinity and ice volume effects which compromise similar marine isotopic proxies of global change. Molarization of apes at 15 ​Ma ago was only one of a series of adaptations selected by at least 9 dry alternating with wet episodes which shifted forest to shrubland ecotones over the past 20 ​m.yr. Our evolutionary lineage ran a gauntlet of Neogene climatic and vegetation changes in Africa by adopting a generalist ecological role.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100005"},"PeriodicalIF":0.0,"publicationDate":"2023-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical fingerprinting of fossils with uncertain stratigraphic provenance: A case study from the Lower Jurassic Nishinakayama Formation (Yamaguchi, Japan)","authors":"Benjamin T. Breeden III ,&nbsp;Kentaro Izumi ,&nbsp;David B. Kemp ,&nbsp;Randall B. Irmis","doi":"10.1016/j.eve.2023.100004","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100004","url":null,"abstract":"<div><p>A fossil without provenance data is problematic because it cannot be placed into meaningful paleoecological and paleobiogeographic contexts. This problem is particularly acute when the fossil is suspected or known to have originated from a formation within which a major interval of biotic and/or paleoenvironmental change has been recognized that could change the paleobiological implications of the taxon in question. Two reptile fossil specimens (a testudinate and a crocodylomorph) preserved within <em>ex situ</em> mudstone cobbles of the Lower Jurassic (Pliensbachian-Toarcian) Nishinakayama Formation in Yamaguchi, Japan exemplify this problem. Both specimens are preserved alongside associated ammonoid fossils that biostratigraphically constrain them to the Toarcian interval of the Nishinakayama Formation, but it is unclear whether their stratigraphic provenance is below, within, or above the interval of the formation that preserves the chemostratigraphic markers of the Toarcian Ocean Anoxic Event (T-OAE, ∼182.5 ​Ma), which were first established at the nearby locality Sakuraguchidani. Herein, we used isotope ratio mass spectrometry and portable energy-dispersive X-ray fluorescence to investigate the geochemistry of sedimentary matrix sampled from each fossil and a new measured stratigraphic section of the Nishinakayama Formation close to where the fossil specimens were found. We interpret a ∼2‰ positive shift in δ¹³C_org at the base of the section as the recovery of the negative carbon isotope excursion associated with the T-OAE, providing additional evidence of the event from a new locality within the Nishinakayama Formation. Linear discriminant analysis (LDA) of the total geochemical dataset was then used to explore the multivariate separateness of binned intervals of the composite section and predict the provenance of each fossil. The results suggest with 93.33% confidence that both fossils were derived from strata above the T-OAE interval. This predictive method can be applied to any fossil collected <em>ex situ</em> with preserved rock matrix and for which the general provenance is known or suspected.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100004"},"PeriodicalIF":0.0,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benthic foraminiferal survival through the early Paleocene (Danian) greenhouse climate interval based on analysis of IODP Site U1457 (Laxmi Basin, Northern Indian Ocean)","authors":"Thulasi Thena ,&nbsp;Dhananjai K. Pandey ,&nbsp;Raj K. Singh ,&nbsp;Nisha Nair ,&nbsp;Roshni K.S.","doi":"10.1016/j.eve.2023.100003","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100003","url":null,"abstract":"<div><p>The early Paleocene (Danian) period included three major events: the Cretaceous-Paleogene (K-Pg) extinction at 66.0 ​Ma, the Dan-C2 hyperthermal at 65.2 ​Ma, and the latest Danian hyperthermal at ∼62.2 ​Ma. In this paper, we investigate benthic foraminiferal diversity patterns, morphotypes, and oxygen conditions along with the carbonates and magnetic susceptibility records at IODP Site U1457 (Laxmi Basin, Northern Indian Ocean) to understand the effects of these Danian events on the marine community in the Indian Ocean. Findings suggest that foraminifera persisted across these major events. Species belonging to <em>Bolivina</em>, <em>Glandulina</em>, <em>Hoeglundina</em>, <em>Parrelloides</em> and <em>Quadrimorphina</em> genus were dominant above the K-Pg boundary whereas <em>Bolivina</em>, <em>Bulimina</em>, <em>Cassidulina</em>, <em>Cornuspira</em>, <em>Gyroidinoides</em>, <em>Melonis</em>, <em>Oolina</em>, <em>Pullenia</em>, <em>Reussoolina</em> and <em>Rutherfordoides</em> dominated across subsequent hyperthermal events. We calculated the average oxygen content at 0.16 ​ml/L in accordance with oxyphilic species abundance, which shows that the Laxmi Basin comprised, mostly, a suboxic to dysoxic environment. The benthic foraminiferal diversity patterns, primary anomalies of calcium carbonates, and magnetic susceptibility, integrated with previously-published global datasets of carbon and oxygen isotopes, help to define the major geologic events at the study site and show how biotas responded to global change during the early Paleocene greenhouse mode.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100003"},"PeriodicalIF":0.0,"publicationDate":"2023-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New 40Ar/39Ar radiometric ages of lamproites indicate latest Tortonian marine restriction of the Fortuna Basin, Eastern Betics, southern Spain","authors":"Luis Gibert ,&nbsp;Alan Deino ,&nbsp;Ariana Carrazana ,&nbsp;David Cruset ,&nbsp;Elisabet Playà ,&nbsp;Jordi Ibáñez-Insa ,&nbsp;Domingo Gimeno ,&nbsp;Javier García-Veigas ,&nbsp;Maria Lería ,&nbsp;Victoriano Pineda","doi":"10.1016/j.eve.2023.100001","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100001","url":null,"abstract":"<div><p>Exposures of lamproitic volcanic rocks have been used to constrain the age of the evaporitic basin-fill in the Fortuna Basin of southern Spain. K/Ar dates initially suggested a Messinian age assignment for these deposits; however, subsequent ⁴⁰Ar/³⁹Ar dates indicated a Tortonian age, implying the early onset of evaporite formation in the eastern Betic Cordillera, in an event termed the “Tortonian Salinity Crisis”. In this paper, we critically review the published chronology of the key igneous outcrops and provide new ⁴⁰Ar/³⁹Ar ages, which show that the Cabezos Negros lamproites lie close to the Tortonian-Messinian boundary (c. 7.25 ​Ma). We also provide new paleomagnetic measurements from each of the three lamproitic outcrops (Cabezos Negros, Derramadores, and El Tale), which demonstrate normal magnetic polarity coincident with episodes of volcanic and subvolcanic activity. The presence of peperites and pillow structures indicate that volcanism at Cabezos Negros was coeval with deposition of the lower part of Rambla Salada Gypsum Member. Therefore, the normal polarity identified in this unit should be equivalent to the normal polarity on the Cabezos Negros lamproites. These results indicate that the initial marine restriction and evaporitic deposition of Fortuna Basin occurred more than a million years before the Messinian Salinity Crisis.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100001"},"PeriodicalIF":0.0,"publicationDate":"2023-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the environmental impacts affecting Cambrian reef building and carbonate settings during the Miaolingian and Furongian epochs: A hypothesis for consideration","authors":"David R. Cordie","doi":"10.1016/j.eve.2023.100002","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100002","url":null,"abstract":"<div><p>The Miaolingian and Furongian epochs of the Cambrian period have been identified as a time of limited metazoan reef development. The aim of this paper is to improve understanding of the biological and geochemical conditions that affected reefs during this interval, and to propose a hypothesis for understanding why metazoan reef development was inhibited. To address these issues, a global dataset of fossil occurrences (N ​= ​25,307) spanning Cambrian Stage 4 to the early Ordovician (Tremadocian) was extracted from the Paleobiology Database, Paleoreef Database, and a review of the primary literature. Findings show that the proportion of reefs constructed by metazoans fell from 40% in the Wuliuan age to 0% in the Drumian age, with reefs being overwhelmingly dominated by microbial ecosystems through the remainder of the Cambrian. The proportion of skeletal material constructed from carbonate fell from 85% in the Wuliuan age to 63% in the Drumian age across all the fossil occurrence data, before recovering. These findings suggest that environmental conditions may have not been favorable to carbonate organisms, but this does not fully explain the prolonged reduction of metazoans within reefs throughout this interval. A hypothesis proposed here is that Miaolingian to Furongian metazoan reef abundances were low because of two factors: (1) shallow water anoxia – and other factors such as elevated temperatures and ocean acidification – caused the extinction of metazoan reef builders in the late-early Cambrian and (2) deep water anoxia and marine regression, resulted in a loss of habitat. These inhibiting conditions were not necessarily concurrent but are inferred to have collectively suppressed the growth of metazoan reefs until the Early Ordovician when more shelf space for new reef development occurred. This hypothesis provides a first step in exploration of these conditions during the middle and late Cambrian and for reef development in general.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100002"},"PeriodicalIF":0.0,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}