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Rowan J, Wood B. Dart and the Taung juvenile: making sense of a century-old record of hominin evolution in Africa. Biol Lett 2024; 20:20240185. [PMID: 39045658 PMCID: PMC11267397 DOI: 10.1098/rsbl.2024.0185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 06/06/2024] [Accepted: 06/17/2024] [Indexed: 07/25/2024] Open
Abstract
The announcement in 1925 by Raymond Dart of the discovery of the Taung juvenile's skull in a quarry in sub-Saharan Africa is deservedly a classic publication in the history of palaeoanthropology. Dart's paper-which designated Taung as the type specimen of the early hominin species Australopithecus africanus-provided the first fossil evidence supporting Charles Darwin's 1871 prediction that Africa was where the human lineage originated. The Taung juvenile's combination of ape and human characteristics eventually led to a paradigm shift in our understanding of human evolution. This contribution focuses on the milieu in which Dart's paper appeared (i.e. what was understood in 1925 about human evolution), the fossil evidence as set out by Dart, his interpretation of how a species represented by a fossilized juvenile's skull fitted within prevailing narratives about human evolution and the significance of the fossil being found in an environment inferred to be very different from that occupied by living apes. We also briefly review subsequent fossil finds that have corroborated the argument Dart made for having discovered evidence of a hitherto unknown close relative of humans, and summarize our current understanding of the earliest stages of human evolution and its environmental context.
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Affiliation(s)
- John Rowan
- Department of Archaeology, University of Cambridge, CambridgeCB2 3DZ, UK
| | - Bernard Wood
- CASHP, Department of Anthropology, George Washington University, Washington, DC20052, USA
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2
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Peppe DJ, Cote SM, Deino AL, Fox DL, Kingston JD, Kinyanjui RN, Lukens WE, MacLatchy LM, Novello A, Strömberg CAE, Driese SG, Garrett ND, Hillis KR, Jacobs BF, Jenkins KEH, Kityo RM, Lehmann T, Manthi FK, Mbua EN, Michel LA, Miller ER, Mugume AAT, Muteti SN, Nengo IO, Oginga KO, Phelps SR, Polissar P, Rossie JB, Stevens NJ, Uno KT, McNulty KP. Oldest evidence of abundant C 4 grasses and habitat heterogeneity in eastern Africa. Science 2023; 380:173-177. [PMID: 37053309 DOI: 10.1126/science.abq2834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
The assembly of Africa's iconic C4 grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including hominins. C4 grasses are thought to have become ecologically dominant in Africa only after 10 million years ago (Ma). However, paleobotanical records older than 10 Ma are sparse, limiting assessment of the timing and nature of C4 biomass expansion. This study uses a multiproxy design to document vegetation structure from nine Early Miocene mammal site complexes across eastern Africa. Results demonstrate that between ~21 and 16 Ma, C4 grasses were locally abundant, contributing to heterogeneous habitats ranging from forests to wooded grasslands. These data push back the oldest evidence of C4 grass-dominated habitats in Africa-and globally-by more than 10 million years, calling for revised paleoecological interpretations of mammalian evolution.
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Affiliation(s)
- Daniel J Peppe
- Department of Geosciences, Baylor University, Waco, TX 76798, USA
| | - Susanne M Cote
- Department of Anthropology and Archaeology, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Alan L Deino
- Berkeley Geochronology Center, Berkeley, CA 94709, USA
| | - David L Fox
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - John D Kingston
- Department of Anthropology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rahab N Kinyanjui
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
- Max Planck Institute for Geoanthropology, D-07743 Jena, Germany
- Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA
| | - William E Lukens
- Department of Geology & Environmental Science, James Madison University, Harrisonburg, VA 22807, USA
| | - Laura M MacLatchy
- Department of Anthropology, University of Michigan, Ann Arbor, MI 48109, USA
- Museum of Paleontology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Alice Novello
- CEREGE, Aix-Marseille Université, CNRS, IRD, Collège de France, INRAE, 13545 Aix en Provence, France
- Department of Biology, Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - Caroline A E Strömberg
- Department of Biology, Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - Steven G Driese
- Department of Geosciences, Baylor University, Waco, TX 76798, USA
| | - Nicole D Garrett
- Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kayla R Hillis
- Department of Earth Sciences, Tennessee Tech University, Cookeville, TN 38505, USA
| | - Bonnie F Jacobs
- Roy M. Huffington Department of Earth Sciences, Southern Methodist University, Dallas, TX 75275, USA
| | - Kirsten E H Jenkins
- Department of Social Sciences, Tacoma Community College, Tacoma, WA 98466, USA
| | - Robert M Kityo
- Department of Zoology Entomology and Fisheries Sciences, Makerere University, Kampala, Uganda
| | - Thomas Lehmann
- Department Messel Research and Mammalogy, Senckenberg Research Institute and Natural History Museum, 60325 Frankfurt, Germany
| | - Fredrick K Manthi
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
| | - Emma N Mbua
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
| | - Lauren A Michel
- Department of Earth Sciences, Tennessee Tech University, Cookeville, TN 38505, USA
| | - Ellen R Miller
- Department of Anthropology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - Amon A T Mugume
- Department of Zoology Entomology and Fisheries Sciences, Makerere University, Kampala, Uganda
- Uganda National Museum, Department of Museums and Monuments, Ministry of Tourism, Wildlife and Antiquities, Kampala, Uganda
| | - Samuel N Muteti
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
- Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Isaiah O Nengo
- Turkana Basin Institute, Stony Brook University, Stony Brook, NY 11794, USA
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Kennedy O Oginga
- Department of Geosciences, Baylor University, Waco, TX 76798, USA
| | - Samuel R Phelps
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Pratigya Polissar
- Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - James B Rossie
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Nancy J Stevens
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, and Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH 45701, USA
| | - Kevin T Uno
- Division of Biology and Paleo Environment, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
| | - Kieran P McNulty
- Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA
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3
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Postcranial evidence of late Miocene hominin bipedalism in Chad. Nature 2022; 609:94-100. [PMID: 36002567 DOI: 10.1038/s41586-022-04901-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 05/24/2022] [Indexed: 11/09/2022]
Abstract
Bipedal locomotion is one of the key adaptations that define the hominin clade. Evidence of bipedalism is known from postcranial remains of late Miocene hominins as early as 6 million years ago (Ma) in eastern Africa1-4. Bipedality of Sahelanthropus tchadensis was hitherto inferred about 7 Ma in central Africa (Chad) based on cranial evidence5-7. Here we present postcranial evidence of the locomotor behaviour of S. tchadensis, with new insights into bipedalism at the early stage of hominin evolutionary history. The original material was discovered at locality TM 266 of the Toros-Ménalla fossiliferous area and consists of one left femur and two, right and left, ulnae. The morphology of the femur is most parsimonious with habitual bipedality, and the ulnae preserve evidence of substantial arboreal behaviour. Taken together, these findings suggest that hominins were already bipeds at around 7 Ma but also suggest that arboreal clambering was probably a significant part of their locomotor repertoire.
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Science Revealing Ancient Magic: Phytolith Evidence from the Early Chalcolithic Site of Isaiia (Eastern Romania). BIOLOGY 2022; 11:biology11081102. [PMID: 35892958 PMCID: PMC9331568 DOI: 10.3390/biology11081102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 11/24/2022]
Abstract
Simple Summary The present paper aims to present the newsworthy results and interpretation of the interdisciplinary analysis conducted at an Early Chalcolithic settlement (Isaiia, Romania). The archaeological campaigns of 2015 and 2017 offered remarkable results including a ceramic vessel, inside which an anthropomorphic figurine (with pregnancy depiction) and a small cone, both made out of clay, were found. Given the special character of the deposition, we collected several samples from the vessel and near it for phytolith analysis; samples of bone found next to the pot and from the nearby features were also dated by AMS radiocarbon. The palaeobotanical evidence based on the phytolith analysis showed that cereals and probably mugwort seem to have been in association with the small artefacts; both, and especially the latter, are known, aside from their practical uses (as aliment or remedy), as powerful symbols, used through the ages in magic practices. All of these facts nuance and augment the cultic interpretation of the deposition as a result of a ritual related to fertility (possibly to counteract some physiological problems or reproductive disorders) involving both feminine and masculine symbols and the use of plants. Abstract The article presents the palaeobotanical investigations of a remarkable discovery from the Early Chalcolithic settlement of Isaiia–Balta Popii (Romania), a multi-layered site. The excavation of a dwelling brought to light a rather rare finding, meaning a medium sized ceramic vessel having deposited inside two objects of burnt clay: an anthropomorphic figurine depicting pregnancy attributes and a small cone. Given the special character of the deposition, several samples from the vessel and near it were collected for phytolith analysis. Our results highlighted a ritual plant deposition: Elongate dendritic and Blocky morphotypes suggest that cereals and probably Artemisia seem to have been used for this purpose. These plants are known, aside from their practical uses, as powerful symbols, used through the ages in magic practices. All of these facts are strong arguments to interpret this find as a result of a ritual related to fertility involving both feminine and masculine symbols and plant use.
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A Phytolith Supported Biosphere-Hydrosphere Predictive Model for Southern Ethiopia: Insights into Paleoenvironmental Changes and Human Landscape Preferences since the Last Glacial Maximum. GEOSCIENCES 2021. [DOI: 10.3390/geosciences11100418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
During the past 25 ka, southern Ethiopia has undergone tremendous climatic changes, from dry and relatively cold during the Last Glacial Maximum (LGM, 25–18 ka) to the African Humid Period (AHP, 15–5 ka), and back to present-day dry conditions. As a contribution to better understand the effects of climate change on vegetation and lakes, we here present a new Predictive Vegetation Model that is linked with a Lake Balance Model and available vegetation-proxy records from southern Ethiopia including a new phytolith record from the Chew Bahir basin. We constructed a detailed paleo-landcover map of southern Ethiopia during the LGM, AHP (with and without influence of the Congo Air Boundary) and the modern-day potential natural landcover. Compared to today, we observe a 15–20% reduction in moisture availability during the LGM with widespread open landscapes and only few remaining forest refugia. We identify 25–40% increased moisture availability during the AHP with prevailing forests in the mid-altitudes and indications that modern anthropogenic landcover change has affected the water balance. In comparison with existing archaeological records, we find that human occupations tend to correspond with open landscapes during the late Pleistocene and Holocene in southern Ethiopia.
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Couvreur TL, Dauby G, Blach‐Overgaard A, Deblauwe V, Dessein S, Droissart V, Hardy OJ, Harris DJ, Janssens SB, Ley AC, Mackinder BA, Sonké B, Sosef MS, Stévart T, Svenning J, Wieringa JJ, Faye A, Missoup AD, Tolley KA, Nicolas V, Ntie S, Fluteau F, Robin C, Guillocheau F, Barboni D, Sepulchre P. Tectonics, climate and the diversification of the tropical African terrestrial flora and fauna. Biol Rev Camb Philos Soc 2021; 96:16-51. [PMID: 32924323 PMCID: PMC7821006 DOI: 10.1111/brv.12644] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 08/07/2020] [Accepted: 08/13/2020] [Indexed: 12/30/2022]
Abstract
Tropical Africa is home to an astonishing biodiversity occurring in a variety of ecosystems. Past climatic change and geological events have impacted the evolution and diversification of this biodiversity. During the last two decades, around 90 dated molecular phylogenies of different clades across animals and plants have been published leading to an increased understanding of the diversification and speciation processes generating tropical African biodiversity. In parallel, extended geological and palaeoclimatic records together with detailed numerical simulations have refined our understanding of past geological and climatic changes in Africa. To date, these important advances have not been reviewed within a common framework. Here, we critically review and synthesize African climate, tectonics and terrestrial biodiversity evolution throughout the Cenozoic to the mid-Pleistocene, drawing on recent advances in Earth and life sciences. We first review six major geo-climatic periods defining tropical African biodiversity diversification by synthesizing 89 dated molecular phylogeny studies. Two major geo-climatic factors impacting the diversification of the sub-Saharan biota are highlighted. First, Africa underwent numerous climatic fluctuations at ancient and more recent timescales, with tectonic, greenhouse gas, and orbital forcing stimulating diversification. Second, increased aridification since the Late Eocene led to important extinction events, but also provided unique diversification opportunities shaping the current tropical African biodiversity landscape. We then review diversification studies of tropical terrestrial animal and plant clades and discuss three major models of speciation: (i) geographic speciation via vicariance (allopatry); (ii) ecological speciation impacted by climate and geological changes, and (iii) genomic speciation via genome duplication. Geographic speciation has been the most widely documented to date and is a common speciation model across tropical Africa. We conclude with four important challenges faced by tropical African biodiversity research: (i) to increase knowledge by gathering basic and fundamental biodiversity information; (ii) to improve modelling of African geophysical evolution throughout the Cenozoic via better constraints and downscaling approaches; (iii) to increase the precision of phylogenetic reconstruction and molecular dating of tropical African clades by using next generation sequencing approaches together with better fossil calibrations; (iv) finally, as done here, to integrate data better from Earth and life sciences by focusing on the interdisciplinary study of the evolution of tropical African biodiversity in a wider geodiversity context.
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Affiliation(s)
| | - Gilles Dauby
- AMAP Lab, IRD, CIRAD, CNRS, INRAUniversity of MontpellierMontpellierFrance
- Laboratoire d'évolution Biologique et Ecologie, Faculté des SciencesUniversité Libre de BruxellesCP160/12, Avenue F.D. Roosevelt 50Brussels1050Belgium
| | - Anne Blach‐Overgaard
- Section for Ecoinformatics & Biodiversity, Department of BiologyAarhus UniversityNy Munkegade 114Aarhus CDK‐8000Denmark
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of BiologyAarhus UniversityNy Munkegade 114Aarhus CDK‐8000Denmark
| | - Vincent Deblauwe
- Center for Tropical Research (CTR), Institute of the Environment and SustainabilityUniversity of California, Los Angeles (UCLA)Los AngelesCA90095U.S.A.
- International Institute of Tropical Agriculture (IITA)YaoundéCameroon
| | | | - Vincent Droissart
- AMAP Lab, IRD, CIRAD, CNRS, INRAUniversity of MontpellierMontpellierFrance
- Laboratoire de Botanique Systématique et d'Écologie, École Normale SupérieureUniversité de Yaoundé IPO Box 047YaoundéCameroon
- Herbarium et Bibliothèque de Botanique AfricaineUniversité Libre de BruxellesBoulevard du TriompheBrusselsB‐1050Belgium
- Africa & Madagascar DepartmentMissouri Botanical GardenSt. LouisMOU.S.A.
| | - Oliver J. Hardy
- Laboratoire d'évolution Biologique et Ecologie, Faculté des SciencesUniversité Libre de BruxellesCP160/12, Avenue F.D. Roosevelt 50Brussels1050Belgium
| | - David J. Harris
- Royal Botanic Garden Edinburgh20A Inverleith RowEdinburghU.K.
| | | | - Alexandra C. Ley
- Institut für Geobotanik und Botanischer GartenUniversity Halle‐WittenbergNeuwerk 21Halle06108Germany
| | | | - Bonaventure Sonké
- Laboratoire de Botanique Systématique et d'Écologie, École Normale SupérieureUniversité de Yaoundé IPO Box 047YaoundéCameroon
| | | | - Tariq Stévart
- Herbarium et Bibliothèque de Botanique AfricaineUniversité Libre de BruxellesBoulevard du TriompheBrusselsB‐1050Belgium
- Africa & Madagascar DepartmentMissouri Botanical GardenSt. LouisMOU.S.A.
| | - Jens‐Christian Svenning
- Section for Ecoinformatics & Biodiversity, Department of BiologyAarhus UniversityNy Munkegade 114Aarhus CDK‐8000Denmark
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of BiologyAarhus UniversityNy Munkegade 114Aarhus CDK‐8000Denmark
| | - Jan J. Wieringa
- Naturalis Biodiversity CenterDarwinweg 2Leiden2333 CRThe Netherlands
| | - Adama Faye
- Laboratoire National de Recherches sur les Productions Végétales (LNRPV)Institut Sénégalais de Recherches Agricoles (ISRA)Route des Hydrocarbures, Bel Air BP 1386‐ CP18524DakarSenegal
| | - Alain D. Missoup
- Zoology Unit, Laboratory of Biology and Physiology of Animal Organisms, Faculty of ScienceUniversity of DoualaPO Box 24157DoualaCameroon
| | - Krystal A. Tolley
- South African National Biodiversity InstituteKirstenbosch Research CentrePrivate Bag X7, ClaremontCape Town7735South Africa
- School of Animal, Plant and Environmental SciencesUniversity of the WitwatersrandPrivate Bag 3Wits2050South Africa
| | - Violaine Nicolas
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, EPHEUniversité des AntillesCP51, 57 rue CuvierParis75005France
| | - Stéphan Ntie
- Département de Biologie, Faculté des SciencesUniversité des Sciences et Techniques de MasukuFrancevilleBP 941Gabon
| | - Frédiéric Fluteau
- Institut de Physique du Globe de Paris, CNRSUniversité de ParisParisF‐75005France
| | - Cécile Robin
- CNRS, Géosciences Rennes, UMR6118University of RennesRennes35042France
| | | | - Doris Barboni
- CEREGE, Aix‐Marseille University, CNRS, IRD, Collège de France, INRA, Technopole Arbois MéditerranéeBP80Aix‐en‐Provence cedex413545France
| | - Pierre Sepulchre
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA‐CNRS‐UVSQUniversité Paris‐SaclayGif‐sur‐YvetteF‐91191France
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Abstract
Broad-leaved trees are widely distributed from tropical to temperate zones in China, reference collections of phytoliths from these taxa are crucial for the precise reconstruction of paleoenvironments and the study of early plant resource exploitation. However, not much has been published on the phytoliths produced by modern broad-leaved trees. In this study, we collected samples of 110 species that cover the common species distributed in Northern and Southern China, and extracted phytoliths from leaves, twigs and fruits, in order to investigate the phytoliths types and production in these species. We found that only 58 species were phytoliths producers, and that 23 distinct phytoliths morphotypes could be recognized. The results showed that phytoliths types and production in Northern and Southern China could be similar in the two regions. Through analyzing previously published data and our data, Elongate brachiate geniculate, Polygonal tabular, Elongate facetate, Tracheary annulate/facetate geniculate and Tracheary annulate/facetate claviform have been proposed to be the potential diagnostic types for broad-leaved trees in general. This study provided a preliminary reference of phytoliths in modern broad-leaved trees, and could be used in the identification of phytoliths in sediments and archaeological contexts.
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Liu L, Li D, Jie D, Liu H, Gao G, Li N. Translocation of Phytoliths Within Natural Soil Profiles in Northeast China. FRONTIERS IN PLANT SCIENCE 2019; 10:1254. [PMID: 31681366 PMCID: PMC6812660 DOI: 10.3389/fpls.2019.01254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/09/2019] [Indexed: 05/23/2023]
Abstract
Phytoliths are a reliable paleovegetation proxy and have made an important contribution to paleoclimatic studies. However, little is known about the depositional processes affecting soil phytoliths, which limits their use for paleoclimate and paleovegetation reconstructions. Here, we present the results of a study of the vertical translocation characteristics of phytoliths in 40 natural soil profiles in Northeast China. The results show that phytolith concentration decreases within the humic horizon of the soil profiles and that ∼22% of the phytoliths are translocated below the surface of the studied soils. In addition, we find that the translocation rate of phytoliths varies markedly with phytolith type and that phytolith size and aspect ratio also have a significant effect. Phytoliths with length >30 μm and with aspect ratio >2 and those with length <20 μm and aspect ratio <2 are preferentially translocated compared to those with length >25 μm and aspect ratio <2. Our results demonstrate that differential translocation of phytoliths within soil profiles should be considered when using soil phytoliths for paleoclimate and paleovegetation reconstruction.
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Affiliation(s)
- Lidan Liu
- College of Resources and Environmental Science, Hunan Normal University, Changsha, China
| | - Dehui Li
- Institute for Peat and Mire Research, State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Northeast Normal University, Changchun, China
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, China
| | - Dongmei Jie
- Institute for Peat and Mire Research, State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Northeast Normal University, Changchun, China
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, China
| | - Hongyan Liu
- Resources Environment & Tourism, Anyang Normal University, Anyang, China
| | - Guizai Gao
- Institute for Peat and Mire Research, State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Northeast Normal University, Changchun, China
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, China
| | - Nannan Li
- Institute for Peat and Mire Research, State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Northeast Normal University, Changchun, China
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, Changchun, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, China
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9
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Thummel RV, Brightly WH, Strömberg CAE. Evolution of phytolith deposition in modern bryophytes, and implications for the fossil record and influence on silica cycle in early land plant evolution. THE NEW PHYTOLOGIST 2019; 221:2273-2285. [PMID: 30347428 DOI: 10.1111/nph.15559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 10/15/2018] [Indexed: 06/08/2023]
Abstract
Anecdotal evidence indicating substantial silica accumulation in tissues of bryophytes suggests that silica (phytolith) deposition evolved early on in embryophytes. To test this hypothesis, we conducted the first survey of phytolith content representing the major liverwort, moss and hornwort clades. We also assessed the diagnostic value of bryophyte phytoliths. Silica extracted from bryophyte material through wet-ashing was described, focusing on abundance, classifying taxa as nonproducers, light producers and higher producers; and phytolith morphotypes. Ancestral state reconstruction of these characters was performed for mosses and liverworts using published phylogenies. Phytoliths are present in multiple subclades within liverworts, mosses and hornworts, but these phyla were not ancestrally high silica-producers. Higher deposition occurs in liverworts and mosses with specialized water-conducting cells. We hypothesize that active, high silica accumulation was not ancestral for embryophytes, but became possible in clades with increased water conductance. Phytoliths of diagnostic structures (e.g. pegged rhizoids) could help track bryophyte clades or water conductance evolution in the fossil record.
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Affiliation(s)
- Ryan V Thummel
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Box 351800, Seattle, WA, 98195-1800, USA
| | - William H Brightly
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Box 351800, Seattle, WA, 98195-1800, USA
| | - Caroline A E Strömberg
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Box 351800, Seattle, WA, 98195-1800, USA
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10
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Forest extent and deforestation in tropical Africa since 1900. Nat Ecol Evol 2017; 2:26-33. [PMID: 29230024 DOI: 10.1038/s41559-017-0406-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 11/06/2017] [Indexed: 11/08/2022]
Abstract
Accurate estimates of historical forest extent and associated deforestation rates are crucial for quantifying tropical carbon cycles and formulating conservation policy. In Africa, data-driven estimates of historical closed-canopy forest extent and deforestation at the continental scale are lacking, and existing modelled estimates diverge substantially. Here, we synthesize available palaeo-proxies and historical maps to reconstruct forest extent in tropical Africa around 1900, when European colonization accelerated markedly, and compare these historical estimates with modern forest extent to estimate deforestation. We find that forests were less extensive in 1900 than bioclimatic models predict. Resultantly, across tropical Africa, ~ 21.7% of forests have been deforested, yielding substantially slower deforestation than previous estimates (35-55%). However, deforestation was heterogeneous: West and East African forests have undergone almost complete decline (~ 83.3 and 93.0%, respectively), while Central African forests have expanded at the expense of savannahs (~ 1.4% net forest expansion, with ~ 135,270 km2 of savannahs encroached). These results suggest that climate alone does not determine savannah and forest distributions and that many savannahs hitherto considered to be degraded forests are instead relatively old. These data-driven reconstructions of historical biome distributions will inform tropical carbon cycle estimates, carbon mitigation initiatives and conservation planning in both forest and savannah systems.
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