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David L. Dilcher - One of the best experts on this subject based on the ideXlab platform.
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Montsechia, an ancient aquatic angiosperm
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Bernard Gomez, Véronique Daviero-gomez, Carles Martín-closas, Clement Coiffard, David L. DilcherAbstract:The early diversification of angiosperms in diverse ecological niches is poorly understood. Some have proposed an origin in a darkened forest habitat and others an open aquatic or near aquatic habitat. The research presented here centers on Montsechia vidalii, first recovered from lithographic limestone deposits in the Pyrenees of Spain more than 100 y ago. This fossil material has been poorly understood and misinterpreted in the past. Now, based upon the study of more than 1,000 carefully prepared specimens, a detailed analysis of Montsechia is presented. The morphology and anatomy of the plant, including aspects of its reproduction, suggest that Montsechia is sister to Ceratophyllum (whenever cladistic analyses are made with or without a backbone). Montsechia was an aquatic angiosperm living and reproducing below the surface of the water, similar to Ceratophyllum. Montsechia is Barremian in age, raising questions about the very early divergence of the Ceratophyllum clade compared with its position as sister to eudicots in many cladistic analyses. Lower Cretaceous aquatic angiosperms, such as Archaefructus and Montsechia, open the possibility that aquatic plants were locally common at a very early stage of angiosperm evolution and that aquatic habitats may have played a major role in the diversification of some early angiosperm lineages.
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A eudicot from the Early Cretaceous of China
Nature, 2011Co-Authors: David L. Dilcher, Hongshan Wang, Zhiduan ChenAbstract:The early history of flowering plants (angiosperms) is contentious, but a steady stream of fossil discoveries from the Early Cretaceous of China is beginning to fill in some of the gaps in our knowledge. The latest of these, found in the Lower Cretaceous Yixian Formation, is a fossil that dates to between 124.4 million and 122.9 million years old. It is particularly informative because this angiosperm is a eudicot — the relatively derived group that dominates the flowering plants in the world today — and is also possibly a member of the Ranunculaceae. The fossil confirms the presence of the eudicots at this time and documents an early burst of angiosperm evolution. The early history of flowering plants (angiosperms) is contentious. However, many fossils attributable to flowering plants have been found in the Early Cretaceous of China. The plant reported in this study goes a step further: not only is it an angiosperm, but it is a member of a relatively derived group, the eudicots, and possibly a member of the Ranunculaceae, an extant family of plants. This indicates that angiosperm evolution probably got into its stride even earlier than the Early Cretaceous. The current molecular systematics of angiosperms1 recognizes the basal angiosperms and five major angiosperm lineages: the Chloranthaceae, the magnoliids, the monocots, Ceratophyllum and the eudicots, which consist of the basal eudicots and the core eudicots2. The eudicots form the majority of the angiosperms in the world today. The flowering plants are of exceptional evolutionary interest because of their diversity of over 250,000 species and their abundance as the dominant vegetation in most terrestrial ecosystems, but little is known of their very early history. In this report we document an early presence of eudicots during the Early Cretaceous Period. Diagnostic characters of the eudicot fossil Leefructus gen. nov. include simple and deeply trilobate leaves clustered at the nodes in threes or fours, basal palinactinodromous primary venation, pinnate secondary venation, and a long axillary reproductive axis terminating in a flattened receptacle bearing five long, narrow pseudo-syncarpous carpels. These morphological characters suggest that its affinities are with the Ranunculaceae, a basal eudicot family. The fossil co-occurs with Archaefructus sinensis3 and Hyrcantha decussata4 whereas Archaefructus liaoningensis5 comes from more ancient sediments. Multiple radiometric dates of the Lower Cretaceous Yixian Formation place the bed yielding this fossil at 122.6–125.8 million years old6,7,8. The earliest fossil records of eudicots are 127 to 125 million years old, on the basis of pollen9,10. Thus, Leefructus gen. nov. suggests that the basal eudicots were already present and diverse by the latest Barremian and earliest Aptian.
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A review of recent advances in the study of early angiosperms from northeastern China
Palaeoworld, 2008Co-Authors: Ge Sun, David L. Dilcher, Shao-lin ZhengAbstract:Abstract The last 10 years (1998–2007) were very productive and important in the study of early angiosperms in northeastern China. The new discoveries of the earliest well-documented records of angiosperms such as Archaefructus, as well as Hyrcantha decussata (= Sinocarpus decussatus), provided fresh knowledge for better understanding the primitive characters of the ancient angiosperms and also their aquatic (or wet) habitat and their herbaceous nature. Some new approaches such as the combination of molecular and morphological characters joined together to place Archaefructus in the angiosperm phylogenetic framework. These fossils demonstrate that we should expect more ancient angiosperms to be found in the pre-Cretaceous which will continue to add important new understanding to the nature of the origin and evolution of the angiosperms.
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Fresh approach to the study of fossil plants
Trends in Plant Science, 2002Co-Authors: David L. DilcherAbstract:The Evolution of Plantsby K.J. Willis and J.C. McElwain, Oxford University Press, 2002. $40.00/£22.95 pbk (x + 378 pages) ISBN 0 19 850065 3View Large Image | Download PowerPoint SlideThe focus of this interesting and readable new book in paleobotany is evolution. This focus upon evolution requires that a great deal of attention to be given to the ecology and functional morphology of plants through time. It is these aspects of The Evolution of Plants that make it so interesting and informative. The major themes presented in the book are how fossils are formed, early life, colonization of land, early trees, seed plant evolution, flowering plant origins, mass extinctions, ancient DNA, and evolution theory applied to the fossil plant record. This organization is logical and breaks away from the more common organization of paleobotany textbooks along phylogenetic lines. The increasing complexity of plant life through time tends to provide a sequence in this book that parallels the modern classification of plants. It includes many cladograms and charts showing the natural relationships of plants.The presentation of major trends in the evolution of plants carries the reader through time and increasing complexity of the structure, reproductive biology and the development of plant communities and plant–animal interactions. Attention is also given to CO2 fluctuations and major pulses in the abiotic world. Plant fossil records are mapped in relation to the CO2 estimates several times in an effort to demonstrate how the evolution of plant taxa relate to the CO2 environments in which they evolved. Paleovegetation world maps are frequently presented showing the distribution of various fossil assemblages at different ages in Earth's history from the early Devonian through the Miocene. The evolution of plants presented in graphic form in relation to their environment and their geography allows the reader to comprehend the whole of the Earth's vegetation as it changed through time. This concept is further emphasized by the repeated presentation of charts showing the species abundance of each major plant taxa through time. The book is well illustrated with figures, diagrams and reconstructions. Although many are redrawn from various textbooks and papers and vary in quality, they are all informative and add to the book's usefulness. However, changes in the proportions of some redrawn figures (such as Figure 6.3) alter the nature of the original reconstruction.As with any first edition of a new book, there is bound to be some omissions and minor copy mistakes (Proauaucaria should be Pararaucaria, Figure 1.4). A few of the omissions should be mentioned because they are important events in the evolution of plants. When discussing the evolution of heterospory it would be useful to mention the independent and parallel evolution of the megaspores and microspores found in the late Devonian aquatic heterosporous lycopods [1xThe functional biology of Devonian spores with bifurcate processes – a hypothesis (Essays in Evolutionary Plant Biology). Dilcher, D.L. et al. The Palaeobotanist. 1992; 41: 67–74See all References][1] and the Cretaceous aquatic heterosporous ferns. Important steps in the evolution of pollen are also omitted. It is significant that Gingko and the cycads still reproduce by ancient prepollen, dating from Permian times [2xZoidogamy in fossil gymnosperms: the centenary of a concept, with special references to prepollen of late Paleozoic conifers. Poort, R.J. et al. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 11713–11717Crossref | PubMed | Scopus (32)See all References][2]. In addition there is no clear focus upon the closed carpel as the important defining character of angiosperms. This key character was used to define Archaefrutus as one of the oldest known early angiosperms. However, no mention is made of Archaefrutus [3xIn search of the first flower: a Jurassic angiosperm, Archaefructus from N.E. China. Sun, G. et al. Science. 1998; 282: 1692–1695Crossref | PubMedSee all References][3] in the section ‘Evidence for the first Angiosperms’ or ‘Flower parts’ in Chapter 6. Instead, it is considered along with the problematic angiosperms Crinopolles and Furcula.Extreme care needs to be taken when drawing direct relationships from the fossil record to extant taxa at the generic level. There seems to be a tendency in this book to relate early fossil angiosperms to extant taxa and then assume that an extant family, the Platanaceae (Table 8.3), has been in existence for 120 million years. This practice is what led Ledyard Stebbins to ignore the fossil record when writing about angiosperm evolution [4xToward a new synthesis: major evolutionary trends in the angiosperm fossil record. Dilcher, D.L. : 255–270See all References][4].This book is a welcome addition to paleobotany. The chapter summaries and the glossary are useful parts of the book and make it attractive to students. It is a book that should be used in the classroom when teaching classes in plant evolution, paleobotany, phytogeography and plant morphology. It is useful as a general reference for plant evolution rather than a reference manual about the details of fossil plants that are cited frequently in the text.
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Archaefructaceae, a new basal angiosperm family.
Science (New York N.Y.), 2002Co-Authors: Ge Sun, David L. Dilcher, Shao-lin Zheng, Kevin C. Nixon, Xinfu WangAbstract:Archaefructaceae is proposed as a new basal angiosperm family of herbaceous aquatic plants. This family consists of the fossils Archaefructus liaoningensis and A. sinensis sp. nov. Complete plants from roots to fertile shoots are known. Their age is a minimum of 124.6 million years from the Yixian Formation, Liaoning, China. They are a sister clade to all angiosperms when their characters are included in a combined three-gene molecular and morphological analysis. Their reproductive axes lack petals and sepals and bear stamens in pairs below conduplicate carpels.
Xin Wang - One of the best experts on this subject based on the ideXlab platform.
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Flowers from the Early Cretaceous
The Dawn Angiosperms, 2018Co-Authors: Xin WangAbstract:Fossil angiosperms from the Early Cretaceous are of special interest because currently the earliest widely-accepted angiosperms are of this age. Chaoyangia, Archaefructus, Sinocarpus, Callianthus, Liaoningfructus, Baicarpus, and Nothodichocarpum are representative angiosperms from the Yixian Formation (125 Ma, Early Cretaceous). Their early age, distinct morphology, and reproductive features not only display an aspect of early angiosperms, but also, if monophyly of angiosperms is assumed, strongly suggest that the origin of angiosperms must have occurred even earlier.
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A Biased, Misleading Review on Early Angiosperms
Natural Science, 2017Co-Authors: Xin WangAbstract:A recently published review by Herendeen et al. is misleading, self-centered, self-praising, and self-conflicting. They excluded the famous early angiosperm Archaefructus from their list of exemplar angiosperms, which contained only fossil plants they published themselves, leaving the impression that they were only authoritative on the origin and early history of angiosperms. Their 57-year-old “No Angiosperms Until the Cretaceous” conception does not reflect the truth about the origin and early history of angiosperms. Reinforcing such vapidly repeated statement does not help resolving any problem in science but leads to no solution for the origin of angiosperms. The authors tried to establish a criterion identifying a fossil angiosperm but their own exemplar angiosperm Monetianthus overturns their own criterion. Apparently, such a review does not positively contribute much to science.
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Reconsiderations on two characters of early angiosperm Archaefructus
Palaeoworld, 2012Co-Authors: Xin Wang, Xiao-ting ZhengAbstract:Abstract Archaefructus is a genus of considerable interest and importance in the study of early angiosperms. Three previously documented species have provided important information about early angiosperms, although some of their characters have been interpreted in various ways. Additional new materials presented in this paper along with the holotype of Archaefructus liaoningensis illustrate branching pattern, fruit arrangement, and seed attachment in Archaefructus . New observations indicate that Archaefructus has ovules/seeds attached to the midrib on the abaxial side of the fruits and a whorled/opposite arrangement for the fruits on the axis. New fossil material of Archaefructus sinensis demonstrates that fruit pairs are inserted on the infructescence axis oppositely. The diagnoses of Archaefructus and Archaefructaceae are emended, and their significance on early angiosperm evolution is discussed.
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The Earliest Normal Flower from Liaoning Province, China
Journal of integrative plant biology, 2009Co-Authors: Xin Wang, Shao-lin ZhengAbstract:The early evolution of angiosperms has been a focus of intensive research for more than a century. The Yixian Formation in western Liaoning yields one of the earliest angiosperm macrofloras. Despite multitudes of angiosperm fossils uncovered, including Archaefructus and Sinocarpus, no bona fide normal flower has been dated to 125 Ma (mega-annum) or older. Here we report Callianthus dilae gen. et sp. nov. from the Yixian Formation (Early Cretaceous) in western Liaoning, China as the earliest normal flower known to date. The flower demonstrates a typical floral organization, including tepals, androecium, and gynoecium. The tepals are spatulate with parallel veins. The stamens have a slender filament, a globular anther, bristles at the anther apex, and in situ round-triangular pollen grains. The gynoecium is composed of two stylate carpels enclosed in a fleshy envelope, and develops into a "hip" when mature. Since the well-accepted history of angiosperms is not much longer than 125 Ma, Callianthus together with Chaoyangia, Archaefructus and Sinocarpus from the Yixian Formation demonstrate a surprisingly high diversity of angiosperms, implying a history of angiosperms much longer than currently accepted.
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Schmeissneria: A missing link to angiosperms?
BMC Evolutionary Biology, 2007Co-Authors: Xin Wang, Shuying Duan, Baoyin Geng, Yong YangAbstract:The origin of angiosperms has been under debate since the time of Darwin. While there has been much speculation in past decades about pre-Cretaceous angiosperms, including Archaefructus, these reports are controversial. The earliest reliable fossil record of angiosperms remains restricted to the Cretaceous, even though recent molecular phylogenetic studies suggest an origin for angiosperms much earlier than the current fossil record. In this paper, after careful SEM and light microscopic work, we report fossils with angiospermous traits of the Jurassic age. The fossils were collected from the Haifanggou Formation (middle Jurassic) in western Liaoning, northeast China. They include two female structures and an associated leaf on the same slab. One of the female structures is physically connected to the apex of a short shoot. The female organs are borne in pairs on short peduncles that are arranged along the axis of the female structure. Each of the female organs has a central unit that is surrounded by an envelope with characteristic longitudinal ribs. Each central unit has two locules completely separated by a vertical septum. The apex of the central unit is completely closed. The general morphology places these fossils into the scope of Schmeissneria, an early Jurassic genus that was previously attributed to Ginkgoales. Because the closed carpel is a character only found in angiosperms, the closed apex of the central unit suggests the presence of angiospermy in Schmeissneria. This angiospermous trait implies either a Jurassic angiosperm or a new seed plant group parallel to angiosperms and other known seed plants. As an angiosperm, the Liassic age (earliest Jurassic) of Schmeissneria microstachys would suggest an origin of angiosperms during the Triassic. Although still uncertain, this could have a great impact on our perspective of the history, diversity and systematics of seed plants and angiosperms.
Shao-lin Zheng - One of the best experts on this subject based on the ideXlab platform.
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The Earliest Normal Flower from Liaoning Province, China
Journal of integrative plant biology, 2009Co-Authors: Xin Wang, Shao-lin ZhengAbstract:The early evolution of angiosperms has been a focus of intensive research for more than a century. The Yixian Formation in western Liaoning yields one of the earliest angiosperm macrofloras. Despite multitudes of angiosperm fossils uncovered, including Archaefructus and Sinocarpus, no bona fide normal flower has been dated to 125 Ma (mega-annum) or older. Here we report Callianthus dilae gen. et sp. nov. from the Yixian Formation (Early Cretaceous) in western Liaoning, China as the earliest normal flower known to date. The flower demonstrates a typical floral organization, including tepals, androecium, and gynoecium. The tepals are spatulate with parallel veins. The stamens have a slender filament, a globular anther, bristles at the anther apex, and in situ round-triangular pollen grains. The gynoecium is composed of two stylate carpels enclosed in a fleshy envelope, and develops into a "hip" when mature. Since the well-accepted history of angiosperms is not much longer than 125 Ma, Callianthus together with Chaoyangia, Archaefructus and Sinocarpus from the Yixian Formation demonstrate a surprisingly high diversity of angiosperms, implying a history of angiosperms much longer than currently accepted.
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A review of recent advances in the study of early angiosperms from northeastern China
Palaeoworld, 2008Co-Authors: Ge Sun, David L. Dilcher, Shao-lin ZhengAbstract:Abstract The last 10 years (1998–2007) were very productive and important in the study of early angiosperms in northeastern China. The new discoveries of the earliest well-documented records of angiosperms such as Archaefructus, as well as Hyrcantha decussata (= Sinocarpus decussatus), provided fresh knowledge for better understanding the primitive characters of the ancient angiosperms and also their aquatic (or wet) habitat and their herbaceous nature. Some new approaches such as the combination of molecular and morphological characters joined together to place Archaefructus in the angiosperm phylogenetic framework. These fossils demonstrate that we should expect more ancient angiosperms to be found in the pre-Cretaceous which will continue to add important new understanding to the nature of the origin and evolution of the angiosperms.
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Archaefructaceae, a new basal angiosperm family.
Science (New York N.Y.), 2002Co-Authors: Ge Sun, David L. Dilcher, Shao-lin Zheng, Kevin C. Nixon, Xinfu WangAbstract:Archaefructaceae is proposed as a new basal angiosperm family of herbaceous aquatic plants. This family consists of the fossils Archaefructus liaoningensis and A. sinensis sp. nov. Complete plants from roots to fertile shoots are known. Their age is a minimum of 124.6 million years from the Yixian Formation, Liaoning, China. They are a sister clade to all angiosperms when their characters are included in a combined three-gene molecular and morphological analysis. Their reproductive axes lack petals and sepals and bear stamens in pairs below conduplicate carpels.
Bernard Gomez - One of the best experts on this subject based on the ideXlab platform.
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Montsechia, an ancient aquatic angiosperm
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Bernard Gomez, Véronique Daviero-gomez, Carles Martín-closas, Clement Coiffard, David L. DilcherAbstract:The early diversification of angiosperms in diverse ecological niches is poorly understood. Some have proposed an origin in a darkened forest habitat and others an open aquatic or near aquatic habitat. The research presented here centers on Montsechia vidalii, first recovered from lithographic limestone deposits in the Pyrenees of Spain more than 100 y ago. This fossil material has been poorly understood and misinterpreted in the past. Now, based upon the study of more than 1,000 carefully prepared specimens, a detailed analysis of Montsechia is presented. The morphology and anatomy of the plant, including aspects of its reproduction, suggest that Montsechia is sister to Ceratophyllum (whenever cladistic analyses are made with or without a backbone). Montsechia was an aquatic angiosperm living and reproducing below the surface of the water, similar to Ceratophyllum. Montsechia is Barremian in age, raising questions about the very early divergence of the Ceratophyllum clade compared with its position as sister to eudicots in many cladistic analyses. Lower Cretaceous aquatic angiosperms, such as Archaefructus and Montsechia, open the possibility that aquatic plants were locally common at a very early stage of angiosperm evolution and that aquatic habitats may have played a major role in the diversification of some early angiosperm lineages.
Pamela S. Soltis - One of the best experts on this subject based on the ideXlab platform.
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Origin and early evolution of angiosperms.
Annals of the New York Academy of Sciences, 2008Co-Authors: Douglas E. Soltis, Charles D Bell, Pamela S. SoltisAbstract:Contributions from paleobotany, phylogenetics, genomics, developmental biology, and developmental genetics have yielded tremendous insight into Darwin’s “abominable mystery”—the origin and rapid diversification of the angiosperms. Analyses of morphological and molecular data reveal a revised “anthophyte clade” consisting of the fossils glossopterids, Pentoxylon, Bennettitales, and Caytonia as sister to angiosperms. Molecular estimates of the age of crown group angiosperms have converged on 140– 180 million years ago (Ma), older than the oldest fossils (132 Ma), suggesting that older fossils remain to be discovered. Whether the first angiosperms were forest shrubs (darkand-disturbed hypothesis) or aquatic herbs (wet-and-wild hypothesis) remains unclear. The near-basal phylogenetic position of Nymphaeales (water lilies), which may include the well-known fossil Archaefructus, certainly indicates that the aquatic habit arose early. After initial, early “experiments,” angiosperms radiated rapidly (≤5 million years [Myr]), yielding the five lineages of Mesangiospermae (magnoliids and Chloranthaceae as sisters to a clade of monocots and eudicots + Ceratophyllaceae). This radiation ultimately produced approximately 97% of all angiosperm species. Updated estimates of divergence times across the angiosperms conducted using nonparametric rate smoothing, with one or multiple fossils, were older than previous reports, whereas estimates using PATHd8 were typically younger. Virtually all angiosperm genomes show evidence of whole-genome duplication, indicating that polyploidy may have been an important catalyst in angiosperm evolution. Although the flower is the central feature of the angiosperms, its origin and subsequent diversification remain major questions. Variation in spatial expression of floral regulators may control major differences in floral morphology between basal angiosperms and eudicot models.