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10. Terminologie utilisée pour les restes d'Angiospermes. A, morphologie générale d'une fleur hermaphrodite. B, terminologie d'une étamine et d'un grain de pollen (exemple d'un grain de type triaperturé).
Source publication
La transition Crétacé inférieur-Crétacé supérieur (environ 100 millions d’années) marque une période cruciale pour l’évolution de certaines plantes à graines. Elle correspond à la rapide radiation des plantes à fleurs et à la réorganisation écologique des Angiospermes et des conifères. Cependant, notre connaissance des plantes à graines durant le C...
Citations
... PPC-SRlCT has also proved to be efficient in the field of palaeobotany. Beamlines from several synchrotrons have previously tested tomographic protocols on diverse kinds of plant preservations, such as impressions, compressions, charcoals, lignites, permineralizations and petrifications (Feist et al., 2005;Friis et al., 2007;Moreau, 2014;Moreau et al., 2014, a, b, c, Strullu-Derrien et al., 2014, allowing a description of the gross morphology and histology without a destructive approach. This technique enables the production of an infinite number of virtual palaeohistological sections. ...
... PPC-SRlCT has also proved to be efficient in the field of palaeobotany. Beamlines from several synchrotrons have previously tested tomographic protocols on diverse kinds of plant preservations, such as impressions, compressions, charcoals, lignites, permineralizations and petrifications (Feist et al., 2005;Friis et al., 2007;Moreau, 2014;Moreau et al., 2014, a, b, c, Strullu-Derrien et al., 2014, allowing a description of the gross morphology and histology without a destructive approach. This technique enables the production of an infinite number of virtual palaeohistological sections. ...
Background and Aims. Terrestrial plant remains in fossilized tree resin are relatively common. However, histology and preservation of plants entombed in Cretaceous ambers remain poorly known. We report an exquisitely preserved conifer leafy axis from 100-million-year-old opaque amber of western France that is assignable to Glenrosa carentonensis Moreau, Néraudeau, Tafforeau & Dépré. The purpose of this paper is to discuss the taphonomy and the use of microtomography for studies of palaeobotanical remains in amber.
Methods. A leafy axis was examined using propagation phase-contrast X-ray synchrotron microtomography with voxel sizes of 14.9, 1.4, and 0.7 µm.
Key Results. The conifer leafy axis described is preserved in three dimensions. Despite desiccation of the specimen within the surrounding amber, the cuticle, as well as most of inner tissues, is preserved in three dimensions down to the cellular level. Epidermis, palisade parenchyma, spongy parenchyma, transfusion tracheids and vascular bundles are clearly distinguished.
Conclusions. Gross morphology and histology of the specimen were revealed using synchrotron microtomography, allowing an unprecedented resolution for the study of soft-bodied plants entombed in amber. The study reveals a peculiar combination of authigenic and duripartic preservation as well as permineralization, and highlights the complexity of taphonomic processes that can occur in amber inclusions. This fossil demonstrates the difficulty of studying amber-preserved plant remains under certain conditions.
Free access-link to pdf of the paper: http://aob.oxfordjournals.org/cgi/reprint/mcw225?ijkey=Y1772MWuzjUIKx6&keytype=ref
... They show distinct lauraceous affinity having bisexual and trimerous flowers with well-developed perianth, paracytic stomata, oil cells, several whorls of fertile stamens as well as staminal appendages, valvate anther dehiscence and a monocarpellate, superior ovary with a single, pendulous anatropous ovule (Drinnan et al., 1990; Viehofen et al., 2008). Abundant angiosperm-dominated floras with numerous remains of inflorescences and flowers have been reported from the lower Upper (Cenomanian) coaly clays of Gard, Languedoc Roussillon , south-eastern France (Moreau, 2014). These reproductive structures provide new opportunity to study the diversity and palaeoenvironment of early Laurasian angiosperms where they were previously poorly known in this part of Europe. ...
Inflorescences of Mauldinia (Lauraceae) are described from the middle Cenomanian Pauletian facies of Gard, Languedoc-Roussillon, south-eastern France. This is the first record of the genus from this part of Europe. Mauldinia sp. is described based on peduncles and lateral units. Isolated, slender peduncles show spirally arranged scars or rarely attached lateral units. Isolated lateral units consist of cladode-like structures showing up to seven flower/fruit scars. Some isolated fruits were found associated with peduncles and lateral units. Fruits are ovoid fruits contain a single, elongated seed. The pericarp consists of epicarp, mesocarp and endocarp. The seed consists of two cotyledons containing well-developed reserve cells. Mauldinia sp. from Gard differs from known Mauldinia species by having longer internodes along the peduncle and by the shape of the lateral units. Sedimentological and palaeontological evidence suggests that Mauldinia sp. from Gard grew in a protected, littoral environment with limited marine influence. This report provides new information to the relatively poorly known Cretaceous record of angiosperms in France. The occurrence of Mauldinia in the lower Upper Cretaceous of Gard corroborates the widespread occurrence of the genus in marginal littoral environments during the mid-Cretaceous.
