Angiosperm - Explore the Science & Experts | ideXlab

Scan Science and Technology

Contact Leading Edge Experts & Companies

Angiosperm

The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Peter R Crane – 1st expert on this subject based on the ideXlab platform

  • Extinct Diversity among Early Cretaceous Angiosperms: Mesofossil Evidence of Early Magnoliales from Portugal
    International Journal of Plant Sciences, 2019
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen

    Abstract:

    Premise of research. Small Angiosperm fossils are diverse in Early Cretaceous mesofossil floras from Portugal and eastern North America. Investigations of these fossils have revealed an unexpectedly high diversity of extinct Angiosperms related to lineages that are now species poor, such as Austrobaileyales, Nymphaeales, and Chloranthaceae. Here we analyze Early Cretaceous fruits and seeds from Portugal that are related to eumagnoliid Angiosperms and that are also important for understanding extinct diversity in early Angiosperms.Methodology. The fossils were prepared by sieving in water; cleaned with HF, HCl, and water; and studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. The systematic conclusion based on comparative studies was tested in a phylogenetic analysis.Pivotal results. We recognize a new group of Angiosperms based on fruits and seeds united by features that are otherwise unusual among Angiosperms. Two genera, Serialis and Riaselis, are establis…

  • fossil seeds with affinities to austrobaileyales and nymphaeales from the early cretaceous early to middle albian of virginia and maryland usa new evidence for extensive extinction near the base of the Angiosperm tree
    , 2018
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen

    Abstract:

    Abstract Early Cretaceous seeds from Virginia and Maryland, USA, part of a diverse complex of exotestal seeds in Early Cretaceous mesofossil floras from North America and Europe, provide new evidence of extensive extinction among early Angiosperms. The seeds are assigned to a new genus, Nitaspermum, with six species: N. taylorii , N. hopewellense , N. crassum , N. virginiense , N. marylandense, and Nitaspermum sp. All seeds are small, anatropous, bitegmic, and exotestal, with the exotesta composed of a single layer of short, columnar sclerenchyma with strongly folded walls. Nitaspermum shows features of extant Austrobaileyales (Illiciaceae) and Nymphaeales but also critical differences precluding assignment to extant families. These discoveries are consistent with predictions from molecular phylogenetics that indicate the differentiation of Illiciaceae and Nymphaeales early in Angiosperm evolution, but the diversity of such seeds underlines the extent to which the pattern of extant Angiosperm diversity has been shaped by widespread extinction early in Angiosperm evolution.

  • Exceptional preservation of tiny embryos documents seed dormancy in early Angiosperms
    Nature, 2015
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen, Marco Stampanoni, Federica Marone

    Abstract:

    The earliest flowering plants bloomed during the Cretaceous, under the feet of the dinosaurs. They are generally thought to have been small, herbaceous plants, adapted for the quick colonization of disturbed or marginal habitats. This hypothesis is dramatically validated by this study of more than 200 Early Cretaceous Angiosperm seeds, preserved in 11 mesofossil floras from eastern North America and Portugal. The seeds were tiny, adapted for rapid dispersal and quick germination; all were preserved during a dormant phase in their development. The discovery of embryos and their associated nutrient storage tissues in exceptionally well-preserved Angiosperm seeds from the Early Cretaceous period. The rapid diversification of Angiosperms through the Early Cretaceous period, between about 130–100 million years ago, initiated fundamental changes in the composition of terrestrial vegetation and is increasingly well understood on the basis of a wealth of palaeobotanical discoveries over the past four decades^ 1 , 2 , 3 , 4 , 5 and their integration with improved knowledge of living Angiosperms^ 3 , 6 . Prevailing hypotheses, based on evidence both from living and from fossil plants, emphasize that the earliest Angiosperms were plants of small stature^ 7 , 8 , 9 , 10 , 11 , 12 with rapid life cycles^ 7 , 8 , 12 , 13 that exploited disturbed habitats^ 3 , 9 , 11 , 13 , 14 in open^ 3 , 9 , 11 , 13 , 14 , or perhaps understorey, conditions^ 15 , 16 . However, direct palaeontogical data relevant to understanding the seed biology and germination ecology of Early Cretaceous Angiosperms are sparse. Here we report the discovery of embryos and their associated nutrient storage tissues in exceptionally well-preserved Angiosperm seeds from the Early Cretaceous. Synchrotron radiation X-ray tomographic microscopy of the fossil embryos from many taxa reveals that all were tiny at the time of dispersal. These results support hypotheses based on extant plants that tiny embryos and seed dormancy are basic for Angiosperms as a whole^ 17 , 18 . The minute size of the fossil embryos, and the modest nutrient storage tissues dictated by the overall small seed size, is also consistent with the interpretation that many early Angiosperms were opportunistic, early successional colonizers of disturbance-prone habitats^ 2 , 15 , 16 .

Else Marie Friis – 2nd expert on this subject based on the ideXlab platform

  • Extinct Diversity among Early Cretaceous Angiosperms: Mesofossil Evidence of Early Magnoliales from Portugal
    International Journal of Plant Sciences, 2019
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen

    Abstract:

    Premise of research. Small Angiosperm fossils are diverse in Early Cretaceous mesofossil floras from Portugal and eastern North America. Investigations of these fossils have revealed an unexpectedly high diversity of extinct Angiosperms related to lineages that are now species poor, such as Austrobaileyales, Nymphaeales, and Chloranthaceae. Here we analyze Early Cretaceous fruits and seeds from Portugal that are related to eumagnoliid Angiosperms and that are also important for understanding extinct diversity in early Angiosperms.Methodology. The fossils were prepared by sieving in water; cleaned with HF, HCl, and water; and studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. The systematic conclusion based on comparative studies was tested in a phylogenetic analysis.Pivotal results. We recognize a new group of Angiosperms based on fruits and seeds united by features that are otherwise unusual among Angiosperms. Two genera, Serialis and Riaselis, are establis…

  • fossil seeds with affinities to austrobaileyales and nymphaeales from the early cretaceous early to middle albian of virginia and maryland usa new evidence for extensive extinction near the base of the Angiosperm tree
    , 2018
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen

    Abstract:

    Abstract Early Cretaceous seeds from Virginia and Maryland, USA, part of a diverse complex of exotestal seeds in Early Cretaceous mesofossil floras from North America and Europe, provide new evidence of extensive extinction among early Angiosperms. The seeds are assigned to a new genus, Nitaspermum, with six species: N. taylorii , N. hopewellense , N. crassum , N. virginiense , N. marylandense, and Nitaspermum sp. All seeds are small, anatropous, bitegmic, and exotestal, with the exotesta composed of a single layer of short, columnar sclerenchyma with strongly folded walls. Nitaspermum shows features of extant Austrobaileyales (Illiciaceae) and Nymphaeales but also critical differences precluding assignment to extant families. These discoveries are consistent with predictions from molecular phylogenetics that indicate the differentiation of Illiciaceae and Nymphaeales early in Angiosperm evolution, but the diversity of such seeds underlines the extent to which the pattern of extant Angiosperm diversity has been shaped by widespread extinction early in Angiosperm evolution.

  • early flowers and Angiosperm evolution
    , 2011
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen

    Abstract:

    Preface 1. Introduction to Angiosperms 2. The nature of the Angiosperm fossil record 3. The environmental context of early Angiosperm evolution 4. Stratigraphic framework and key areas for Cretaceous Angiosperms 5. Angiosperms in context: extant and fossil seed plants 6. Origin and age of Angiosperms 7. Phylogenetic framework and the assignment of fossils to extant groups 8. Fossils near the base of the Angiosperm tree 9. Early fossil Angiosperms of uncertain relationships 10. Early fossils of eumagnoliids 11. Fossils of monocots 12. Fossils of eudicots: early diverging groups 13. Fossils of core eudicots: basal lineages 14. Fossils of core eudicots: rosids 15. Early fossils of eudicots: asterids 16. Patterns of structural diversification in Angiosperm reproductive organs 17. History and evolution of pollination in Angiosperms 18. History and evolution of dispersal in Angiosperms 19. Vegetational context of early Angiosperm diversification 20. The accumulation of Angiosperm diversity References Index.

Taylor S. Feild – 3rd expert on this subject based on the ideXlab platform

  • Fossil evidence for low gas exchange capacities for Early Cretaceous Angiosperm leaves
    Paleobiology, 2020
    Co-Authors: Taylor S. Feild, Gilbert R Upchurch, David S. Chatelet, Timothy J. Brodribb, Kunsiri Chaw Grubbs, Marie-stéphanie Samain, Stefan Wanke

    Abstract:

    The photosynthetic gas exchange capacities of early Angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early Angiosperm success and how Angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early Angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian–early Albian Angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant Angiosperms. Gas exchange capacities for Early Cretaceous Angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later Angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal Angiosperm lineages reveals genuine signals of Early Cretaceous Angiosperm ecophysiology.

  • EVOLUTIONARY VOYAGE OF Angiosperm VESSEL STRUCTURE-FUNCTION AND ITS SIGNIFICANCE FOR EARLY Angiosperm SUCCESS
    International Journal of Plant Sciences, 2012
    Co-Authors: Taylor S. Feild, Jonathan P. Wilson

    Abstract:

    A hypothesized advantage of the building block of the Angiosperm vascular network, the vessel, is often cited as a critical innovation that elevated the competitive abilities of early Angiosperms above nonAngiosperms during the Cretaceous. Here we synthesize recent discoveries on the hydraulic functions of living basal Angiosperm lineages with evidence from the fossil record to trace the early evolutionary significance of vessels in the early ecophysiological radiation of Angiosperms. Evidence from extant comparative biology and the Early Cretaceous fossil record of leaves and wood do not support the hypotheses that vessels improved drought tolerance of Angiosperms, increased Angiosperm’s photosynthetic abilities, or provided an immediate leap in hydraulic capacity. Instead, later tuning of vessel structure for increased flow efficiency—in particular, by the evolution of simple perforation plates—enabled major increases in xylem hydraulic efficiency.

  • fossil evidence for cretaceous escalation in Angiosperm leaf vein evolution
    Proceedings of the National Academy of Sciences of the United States of America, 2011
    Co-Authors: Taylor S. Feild, Gilbert R Upchurch, David S. Chatelet, Timothy J. Brodribb, Ari Iglesias, Andres Baresch, Bernard Gomez, Barbara A R Mohr, Clement Coiffard, Jiri Kvacek

    Abstract:

    The flowering plants that dominate modern vegetation possess leaf gas exchange potentials that far exceed those of all other living or extinct plants. The great divide in maximal ability to exchange CO2 for water between leaves of nonAngiosperms and Angiosperms forms the mechanistic foundation for speculation about how Angiosperms drove sweeping ecological and biogeochemical change during the Cretaceous. However, there is no empirical evidence that Angiosperms evolved highly photosynthetically active leaves during the Cretaceous. Using vein density (DV) measurements of fossil Angiosperm leaves, we show that the leaf hydraulic capacities of Angiosperms escalated several-fold during the Cretaceous. During the first 30 million years of Angiosperm leaf evolution, Angiosperm leaves exhibited uniformly low vein DV that overlapped the DV range of dominant Early Cretaceous ferns and gymnosperms. Fossil Angiosperm vein densities reveal a subsequent biphasic increase in DV. During the first mid-Cretaceous surge, Angiosperm DV first surpassed the upper bound of DV limits for nonAngiosperms. However, the upper limits of DV typical of modern megathermal rainforest trees first appear during a second wave of increased DV during the Cretaceous-Tertiary transition. Thus, our findings provide fossil evidence for the hypothesis that significant ecosystem change brought about by Angiosperms lagged behind the Early Cretaceous taxonomic diversification of Angiosperms.