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On some angiosperm stem diversity from the Cenomanian of Envigne valley (Vienne, western France)

Abstract : Recently, two Konservat - and Konzentrat -lagerstätten fossil plant assemblages have been reported from the Envigne valley, Vienne, western France. Thousands of stem fragments were collected, and they consist of the tree fern Tempskya, and at least five conifers and seven angiosperms. In many known localities of Cretaceous fossil wood, only this latter tissue is conserved, the other stem tissues having been eliminated during both the degradation and fossilization process. There, the majority of them (medulla, wood and liber) are preserved very exquisitely in many specimens, particularly in some of which belonging to angiosperms. The wood of angiosperms show a great histological diversity for many features concerning the size of the vessels, the perforations, the vessel and ray pits, and the axial parenchyma arrangement. The ray features are more homogeneous (type of cells composing the ray, seriation) as well as the presence of thyllosis that appears frequent in the majority of the taxa. The presence of several specimens of each type of wood makes possible to comprehend intraspecific variability. In addition to these typical heteroxylous angiosperms, numerous specimens show a vesselless angiosperm, and they probably belong to Winteraceae. The very broad conformation of its rays may indicate a liana habit. Most specimens attributed to the other angiosperm taxa show a relatively small stem diameter compared to many coniferous specimens suggesting that they were smaller plants and most probably had a shrub habit rather than tree habit. The in-depth study of these two new deposits is particularly promising in the understanding of 1) Cenomanian forest ecosystems (diversity of taxa, size, habit), and, 2) the evolution of angiosperm histological features not only for wood but also for more less-known tissues as medulla and liber.
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https://hal-mnhn.archives-ouvertes.fr/mnhn-03226137
Contributor : Anais Boura <>
Submitted on : Friday, May 14, 2021 - 9:55:54 AM
Last modification on : Tuesday, May 25, 2021 - 11:44:15 AM

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  • HAL Id : mnhn-03226137, version 1

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Anais Boura, Gwenaëlle Saulnier, Bernard Gomez, Véronique Daviero Gomez, Dario De Franceschi, et al.. On some angiosperm stem diversity from the Cenomanian of Envigne valley (Vienne, western France). IPC5, Jul 2018, Paris, France. ⟨mnhn-03226137⟩

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