Synchrotron X-ray imaging of inclusions in amber

Author's personal copy C. R. Palevol 9 (2010) 361–368 Contents lists available at ScienceDirect Comptes Rendus Palevol www.sciencedirect.com General palaeontology Synchrotron X-ray imaging of inclusions in amber Imagerie par rayonnement X synchrotron d’inclusions dans l’ambre Carmen Soriano a,b,∗ , Mike Archer c , Dany Azar d,e , Phil Creaser c , Xavier Delclòs f , Henk Godthelp c , Suzanne Hand c , Allan Jones g , André Nel e , Didier Néraudeau b , Jaime Ortega-Blanco f , Ricardo Pérez-de la Fuente f , Vincent Perrichot b , Erin Saupe h , Mónica Solórzano Kraemer i,j , Paul Tafforeau a a European Synchrotron Radiation Facility - X-Ray Imaging Group, 6, rue Jules-Horowitz, 38000 Grenoble, France CNRS UMR 6118, géosciences & observatoire des sciences de l’université de Rennes, université Rennes 1, campus de Beaulieu, 35042 Rennes, France c School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia d Lebanese University, P.O. Box 26110217, Fanar-Matn, Lebanon e CNRS UMR 7205, Muséum national d’histoire naturelle, 75231 Paris, France f Facultat de Geologia, Universitat de Barcelona, Barcelona 08024, Spain g Australian Key Centre for Microscopy & Microanalysis, University of Sydney, Sydney 2006, Australia h University of Kansas, Lawrence-Kansas 66045, USA i Steinmann Institut für Geologie, Mineralogie und Paläontologie, Bonn 53115, Germany j Senckenberg Forschungsinstitut und Naturmuseum, Frankfurt am Main 60325, Germany b a r t i c l e i n f o Article history: Received 2 March 2010 Accepted after revision 29 July 2010 Available online 29 October 2010 Written on invitation of the Editorial Board Keywords: Amber Synchrotron phase contrast X-ray imaging 3D reconstruction Microtomography a b s t r a c t Over the past six years, organic inclusions preserved in amber samples from outcrops worldwide have been discovered and imaged in 3D using propagation phase contrast based X-ray synchrotron imaging techniques at the European Synchrotron Radiation Facility (ESRF). A brief description of the techniques and protocols used for detecting and 3D non-destructive imaging of amber inclusions is provided. The latest results from the major amber projects in the ESRF are given, illustrating the increasing utility of the imaging capabilities of X-ray synchrotron phase contrast microtomography. © 2010 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved. r é s u m é Mots clés : Ambre Imagerie par rayonnements X Synchrotron en contraste de phase Reconstruction 3D Microtomographie Au cours des six dernières années, de nombreuses inclusions d’organismes préservés dans des ambres d’origines géographiques diverses ont été imagées en trois dimensions, voire découvertes, grâce à la microtomographie à haute résolution en contraste de phase à rayonnement X synchrotron, à l’Installation Européenne de Rayonnement Synchrotron (ESRF, Grenoble, France). Une brève description des techniques et protocoles utilisés pour la détection et l’imagerie 3D non destructive des inclusions de l’ambre est fournie. Les ∗ Corresponding author. E-mail addresses: carmen.soriano@gmail.com, carmen.soriano@esrf.fr (C. Soriano), m.archer@unsw.edu.au (M. Archer), azar@mnhn.fr (D. Azar), philcreaser@grapevine.com.au (P. Creaser), xdelclos@ub.edu (X. Delclòs), h.godthelp@unsw.edu.au (H. Godthelp), s.hand@unsw.edu.au (S. Hand), allan.jones@sydney.edu.au (A. Jones), anel@mnhn.fr (A. Nel), didier.neraudeau@univ-rennes1.fr (D. Néraudeau), j.ortegablanco@ub.edu (J. Ortega-Blanco), perezdelafuente@ub.edu (R. Pérez-de la Fuente), vincent.perrichot@univ-rennes1.fr (V. Perrichot), eesaupe@ku.edu (E. Saupe), msolorzanokraemer@gmail.com (M.S. Kraemer), tafforeau@esrf.fr (P. Tafforeau). 1631-0683/$ – see front matter © 2010 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved. doi:10.1016/j.crpv.2010.07.014 Author's personal copy 362 C. Soriano et al. / C. R. Palevol 9 (2010) 361–368 derniers résultats des principaux projets engagés sur l’ambre à l’ESRF présentés ici montrent l’intérêt croissant des possibilités d’imagerie par microtomographie en rayonnements X synchrotron. © 2010 Académie des sciences. Publié par Elsevier Masson SAS. Tous droits réservés. 1. Introduction Amber results from the fossilization of various tree resins and is found in sediments dating from the Paleozoic to Holocene. Although the oldest ambers with biological remains (microorganisms) date from the Triassic (Schmidt et al., 2006), macroinclusions have not been found in sediments older than the Lower Cretaceous (c.a. Grimaldi and Engel, 2005; Martínez-Delclòs et al., 2004). Due to the exceptional preservation of organisms in amber, these Lagerstätten often preserve a significant part of the ecosystems in which the amber-producing trees lived. Further, ethological behaviour may be captured (such as evidence of phoresis or parasitism). Various studies have demonstrated that it is possible to obtain information about the soft anatomy of organisms preserved in amber (Grimaldi et al., 1994; Penney et al., 2007; Poinar and Hess, 1982), although most of these techniques led to the destruction of the sample (e.g. Grimaldi et al., 1994). Amber opacity varies greatly among deposits and between samples from the same outcrop. In some cases, the transparency of the resin is high enough to allow the study of the inclusions by classical optic methods (binocular, electronic and confocal microscopes). However, in other cases, the inclusions may be obscured by amber impurities, white foams (due to presence of microbubbles) or oxidation or hydration processes (Martínez-Delclòs et al., 2004), greatly decreasing access to anatomical data of the animal or plant preserved in the resin. In extreme cases, the amber pieces are completely opaque, making it virtually impossible to recognize the presence of inclusions inside (MartínezDelclòs et al., 2004; Perrichot, 2004). Recently, a new approach for studying amber inclusions within opaque pieces was published, namely X-ray synchrotron radiation using phase propagation contrast (Tafforeau et al., 2006). This technique was later optimized and applied to a large quantity of opaque French Lower Cretaceous amber material from Charentes (Lak et al., 2008a, 2008b), establishing the basis for the study of amber with synchrotron radiation and its later application to different ambers worldwide. 2. Methods Using third generation synchrotrons, it is possible to obtain a partially coherent X-ray beam due to the small source size and the long distance between the source and the sample (140 meters in the case of the ESRF ID19 beamline). As a result of the coherence, interfaces in the sample create interferential pattern propagation in space. It is then possible to detect enhanced contrast of the sample interfaces just by increasing the distance between the sample and the detector (propagation phase contrast effect). Since the phase contrast effect is far more sensitive than the absorption one, the technique allows for detection of inclusions that would have remained invisible using only absorption contrast (Lak et al., 2008a, 2008b; Tafforeau et al. 2006). This property can be also achieved in some conventional microtomographic devices, but only in small samples at high resolution and low energy (Penney et al., 2007). Nowadays, propagation phase contrast is the most frequently used technique for high-resolution tomographies of inclusions in amber (chiefly performed at the ESRF), with voxel size ranging from 0.35 to 15 ␮m in the case of larger samples. The success of the first study (Tafforeau et al., 2006) prompted further development of X-ray synchrotron imaging for other amber inclusions and deposits (e.g., Lak et al., 2008a). Eighty percent of French Cretaceous amber pieces are opaque (Perrichot, 2004), and as such, it is often difficult to know whether there are inclusions within a given piece. To combat this, Lak et al. (2008b) used optimized phase contrast-based microradiographic protocol to survey large quantities of opaque pieces for possible inclusions. Amber pieces were immersed in water to optimize the phase contrast effect by reducing the relative residual absorption contrast. The microradiographs of the opaque blocks were normalized and then surveyed at real resolution size to look for inclusions. Later, select specimens were imaged by propagation phase contrast X-ray synchrotron microtomography (PPC-SR␮CT) using local tomography protocol (the amber block being, in most of the cases, far larger than the inclusion itself). Energy was adapted depending upon the size and density pattern of the amber blocks (i.e. presence of pyrite requiring higher energy). Resolution was selected to optimize the level of detail necessary for each inclusion. In some cases, we used a multiscale approach, starting with a complete block tomography (when containing several organisms), followed by detailed scans of selected inclusions, and finishing with higher resolution scans of diagnostic parts of these inclusions. Using this method of microradiographic survey and later microtomography, more than 350 specimens were recognized inside the blocks of opaque amber from France, thus opening a new window for palaeoentomology. After acquisition of the scans, the volumes are reconstructed using a filtered back-projection algorithm adapted for local tomography applications (PyHST software, ESRF). The later 3D processing is performed on powerful workstations using the software VGStudioMax (Volume Graphics, Heidelberg, Germany). The segmentation protocol, which virtually extracts the organisms, is based on controlled 3D region growing, fol- Author's personal copy C. Soriano et al. / C. R. Palevol 9 (2010) 361–368 363 Fig. 1. 3D reconstructions of Lower Cretaceous French amber insects using PPC-SR␮CT at ID19 beamline, ESRF, Grenoble. 1: Coleopteran larva, specimen MNHN A33496 (ARC-331.5), voxel size 0.55 ␮m, propagation distance 70 mm, 35 keV, scale bar 500 ␮m. 2: Raphidiopteran pupa, specimen MNHN A33497 (ARC-332.1), voxel size 7.46 ␮m, propagation distance 800 mm, 25 keV, scale bar 5 mm. Fig. 1. Reconstructions 3D d’insectes dans l’ambre Crétacé inférieur de France, effectuées par PPC-SR␮CT sur la ligne de lumière ID19, ESRF, Grenoble. 1 : Larve de Coléoptère, spécimen MNHN A33496 (ARC-331.5), taille de pixel 0,55 ␮m, distance de propagation 70 mm, 35 keV, barre d’échelle 500 ␮m. 2 : Pupe de Raphidioptère, spécimen MNHN A33497 (ARC-332.1), taille de pixel 7,46 ␮m, distance de propagation 800 mm, 25 keV, barre d’échelle 5 mm. Author's personal copy 364 C. Soriano et al. / C. R. Palevol 9 (2010) 361–368 Fig. 2. 3D reconstruction of a monotomid beetle (Rhizophtoma elateroides Kirejtshuk et al., 2009), specimen 1512, Coll. D. Azar, from Lower Cretaceous Lebanese amber using PPC-SR␮CT at BM05 beamline, ESRF, Grenoble. Voxel size 1.03 ␮m, propagation distance 50 mm, 20.5 keV. Scale bar 500 ␮m. Fig. 2. Reconstruction 3D d’un Coléoptère Monotomidé (Rhizophtoma elateroides Kirejtshuk et al., 2009), spécimen 1512, Coll. D. Azar, dans l’ambre Crétacé inférieur du Liban, effectuée par PPC-SR␮CT sur la ligne de lumière BM05, ESRF, Grenoble. Taille de pixel 1,03 ␮m, distance de propagation 50 mm, 20,5 keV. Barre d’échelle 500 ␮m. lowed by manual refinement of the rough first result (Fig. 1). After publication of an exemplar, the microtomographic data is available online in the free access paleontological database at http://paleo.esrf.eu, including original reconstructions of the scan, all the scan parameters, the segmented slices, the VGStudioMax files, .stl surface files for 3D printing, plates and animations with anaglyphic versions. When possible, 3D prints in ABS plus plastic are constructed at the ESRF, which are used as accessible physical representations of the virtual holotypes. The specimens included in these publications are deposited in the following institutions: French and Lebanese amber at the Division of Palaeontology of the Natural History Museum of Paris (MNHN, France), with French amber being provisionally housed at the Geological Department of the University of Rennes 1 (France); Spanish amber in the Fundación Conjunto Paleontológico Dinopolis (CPT) and in the Museo de Ciencias Nacional de Alava (MCNA), Spain; and Australian amber at the Queensland Museum (Australia). 3. Results In the last 6 years, amber pieces from virtually the world over have been scanned or surveyed in the ESRF, but long-term projects have been launched only with amber collections from the Cretaceous of France, Spain, and Lebanon, and from the Tertiary of Australia. The French Cretaceous amber material was the first to be surveyed and microtomographied by synchrotron Xray imaging (Lak et al., 2008b; Tafforeau et al., 2006), and since the beginning of this work, several hundred plant and animal specimens have been recognized. The French Cretaceous amber outcrops are located mainly in the Southwest of France, and their ages range from Albian to Cenomanian (Néraudeau et al., 2002, 2003, 2005, 2008, 2009; Perrichot and Néraudeau, 2009; Perrichot et al., 2007, 2010). As noted, the large quantity of opaque amber pieces (approximately 80%) from the Lower Cretaceous French material spurred study using X-ray synchrotron microtomography (Lak et al., 2008a, 2008b). Because synchrotron imaging was first applied to the French deposit, the material has, at this stage, been reconstructed in 3D and published most extensively (Lak et al., 2008b, 2009; Lak Author's personal copy C. Soriano et al. / C. R. Palevol 9 (2010) 361–368 Fig. 3. Coleoptera (Nemonychidae), specimen CPT-4106, from the Lower Cretaceous Spanish amber. 1: Photography of the specimen with binocular. 2: 3D reconstruction of the complete body. 3: Transverse plane projection, showing the hind wings folded (a) and preserved under the elytra (b) and digestive tract (c). Fig. 3. Coléoptère (Nemonychidae), spécimen CPT-4106, dans l’ambre Crétacé inférieur d’Espagne. 1 : Photo du spécimen à la loupe binoculaire. 2 : Reconstruction 3D du corps complet. 3 : Projection transverse plane montrant les ailes postérieures pliées (a) et préservées sous les élytres (b) et le tube digestif (c). and Nel, 2009; Perrichot et al., 2008; Tafforeau et al., 2006; Vršanský, 2009). The latest discoveries from these amber deposits include different larval stages of various groups of insects, including coleopterans and raphidiopterans (Fig. 1). Formal systematic study of these inclusions is complicated because the larval stages of these families do not resemble the adult stages, but they may contribute to the general ecosystem reconstruction. Data from the specimens are available online on the ESRF paleontological database described above. Furthermore, a great number of 365 new larval and adult forms of dipterans, coleopterans, heteropterans, hymenopterans and other groups are currently under study. Following the success of the French pilot study in late 2008, work began on the Lower Cretaceous amber collection from Lebanon using PPC-SR␮CT at the ESRF. Until now, the Lebanese amber deposits, with more than 300 outcrops, are considered to be the oldest with arthropod inclusions (Azar, 2007), and so far numerous representatives of different groups of arthropods, vertebrates and plants have been recognized. Although the amber is fairly transparent, some pieces were surveyed by microtomography to study the internal features of the inclusions and/or to resolve anatomical details invisible with conventional techniques (as was the case, for example, for the oldest representative of the beetle family Monotomidae) (Fig. 2) (Kirejtshuk et al., 2009). In 2009, a new project studying the fossil content of the Spanish amber outcrops began, and approximately one hundred specimens have already been scanned on the ID19 and BM05 beamlines of the ESRF using PPC-SR␮CT. The Spanish amber dates from the BarremianCenomanian. The first outcrop with paleobiological content was described in 2000 from Albian deposits (Alonso et al., 2000), and since then several outcrops have been discovered that yield a rich collection of animals and plants (Delclòs et al., 2007; Peñalver et al., 2007; Najarro et al., 2009). Spanish amber samples are generally translucent, so Xray synchrotron microradiographic techniques to detect inclusions are not needed. Even so, partial opacity of samples and/or debris within a piece can make the study of morphological details extremely difficult (Fig. 3). In other cases, data on the internal anatomy is required to perform a thorough systematic study. The preservation of internal structures in some Spanish samples has allowed for unprecedented, exhaustive study of the inclusions, for example making it possible to see the hind wings underneath the elytra of beetles (Fig. 3). Other Spanish specimens that have been reconstructed include a female spider of the genus Orchestina (family Oonopidae; Fig. 4) and a mymarommatoid wasp of the genus Galloromma (family Gallorommatidae; Fig. 4), both of which are currently under study (e.g., Ortega-Blanco et al., in press). The Australian Tertiary amber is the newest project currently underway at the ESRF. This material is found on eastern Cape York Peninsula, and although its precise age is the subject of current investigation, its entomological content and geological context suggest a Tertiary age (Bickel, 2009). All the material scanned at the ESRF involved fully opaque pieces; hence the same technique applied to the French Cretaceous opaque amber samples was implemented. From this survey, several arthropod and plant inclusions were recognized, including hymenopterans, hemipterans, dipterans and a diverse group of beetles, some within the family Scolytidae (Fig. 5). Because of the utility of this method and its relevance for amber research, new projects on other significant amber deposits will begin in the near future at the ESRF. Author's personal copy 366 C. Soriano et al. / C. R. Palevol 9 (2010) 361–368 Fig. 4. 3D reconstructions of Lower Cretaceous Spanish amber arthropods using PPC-SR␮CT at BM05 beamline, ESRF, Grenoble. 1: Female spider from San Just outcrop (Orchestina, Oonopidae), specimen CPT-4100, general habitus, voxel size 0.7 ␮m, propagation distance 100 mm, 20 keV. Scale bar 500 ␮m. 2: Galloromma sp., specimen MCNA12630, a wasp of the mymarommatoid family Gallorommatidae from Peñacerrada I outcrop. Voxel size 0.56 ␮m, propagation distance 25 mm, 25 keV. Scale bar 500 ␮m. Fig. 4. Reconstructions 3D d’arthropodes dans l’ambre Crétacé inférieur d’Espagne, effectuées par PPC-SR␮CT sur la ligne de lumière BM05, ESRF, Grenoble. 1 : Araignée Oonopidae femelle (Orchestina sp.) du gisement de San Just, spécimen CPT-4100, aspect général, taille de pixel 0,7 ␮m, distance de propagation 100 mm, 20 keV. Barre d’échelle 500 ␮m. 2 : Galloromma sp., spécimen MCNA12630, guêpe mymarommatoïde de la famille Gallorommatidae du gisement de Peñacerrada I. Taille de pixel 0,56 ␮m, distance de propagation 25 mm, 25 keV. Barre d’échelle 500 ␮m. Author's personal copy C. Soriano et al. / C. R. Palevol 9 (2010) 361–368 367 Fig. 5. 3D reconstruction of a scolytid beetle (Scolytidae) from Tertiary Australian amber using PPC-SR␮CT at ID19 beamline, ESRF, Grenoble. Voxel size 1.37 ␮m, propagation distance 150 mm, 30 keV. Scale bar 1 mm. Fig. 5. Reconstruction 3D d’un Coléoptère Scolytidé dans l’ambre tertiaire d’Australie, effectuée par PPC-SR␮CT sur la ligne de lumière ID19, ESRF, Grenoble. Taille de pixel 1,37 ␮m, distance de propagation 150 mm, 30 keV. Barre d’échelle 1 mm. All projects are closely related through what is now one of the largest worldwide collaborations on the study of amber. Acknowledgements We would like to thank Jose Baruchel, Elodie Boller, and others of ESRF beamlines ID 19 and BM 05 for their support and assistance over the years. This work is a contribution to the projects AMBRACE no. BLAN07-1-184190 from the French National Research Agency, CGL2008-00550/BTE from the Ministry of Science and Innovation of Spain, DP0881440 from the Australian Research Council, and “The Study of the Fossil Insects in Lebanon and their Outcrops: Geology of the Outcrops–Historical and Biodiversity Evolution” from Lebanese University. We also thank Beth Norris and Dale Wicks for access to opaque Australian amber analysed in this study. We are grateful to Luis Alcalá (Dinopolis), Jesús Alonso (Museo de Ciencias de Álava) and Fermín Unzué (El Soplao) for providing material from the Spanish amber outcrops. References Alonso, J., Arillo, A., Barrón, E., Corral, C., Grimalt, J., López, J.F., López, R., Martínez-Delclòs, X., Ortuño, V., Peñalver, E., Trincão, P.R., 2000. A new fossil resin with biological inclusions in Lower Cretaceous deposits from Álava (northern Spain, Basque-Cantabrian basin). J. Paleontol. 74, 158–178. Azar, D., 2007. Preservation and accumulation of biological inclusions in Lebanese amber and their significance. C. R. Palevol 6, 151–156. Bickel, D.J., 2009. The first species described from Cape York amber, Australia: Chaetogonopteron bethnorrisae n.sp. (Diptera: Dolichopodidae). Denisia 26, 35–39. Delclòs, X., Arillo, A., Peñalver, E., Barrón, E., Soriano, C., López del Valle, R., Bernárdez, E., Corral, C., Ortuño, V., 2007. Fossiliferous amber deposits from the Cretaceous (Albian) of Spain. C. R. Palevol 6, 135–149. Grimaldi, D., Bonwich, E., Delannoy, M., Doberstein, S., 1994. Electron microscopic studies of mummified tissues in amber fossils. Amer. Mus. Novit. 3097, 1–31. Grimaldi, D., Engel, M.S., 2005. Evolution of the Insects. Cambridge University Press, New York/Cambridge, USA, 755 p. Kirejtshuk, A.G., Azar, D., Tafforeau, P., Boistel, R., Fernandez, V., 2009. New beetles of Polyphaga (Coleoptera, Polyphaga) from Lower Cretaceous Lebanese amber. Denisia 26, 119–130. Lak, M., Nel, A., 2009. An enigmatic diapriid wasp (Insecta Hymenoptera) from French Cretaceous amber. Geodiversitas 31, 137–144. Lak, M., Azar, D., Nel, A., Néraudeau, D., Tafforeau, P., 2008a. The oldest representative of the Trichomyiinae (Diptera: Psychodidae) from the Lower Cenomanian French amber studied with phase contrast synchrotron X-ray imaging. Invert. Systematics 22, 471–478. Lak, M., Néraudeau, D., Nel, A., Cloetens, P., Perrichot, V., Tafforeau, P., 2008b. Phase contrast X-ray synchrotron imaging: opening access to fossil inclusions in opaque amber. Microsc. Microanal. 14, 251–259. Lak, M., Fleck, G., Azar, D., Engel, M.S., Kaddumi, H.F., Néraudeau, D., Tafforeau, P., Nel, A., 2009. Phase contrast X-ray synchrotron microtomography and the oldest damselflies in amber (Odonata: Zygoptera: Hemiphlebiidae). Zool. J. Linn. Soc. Lond. 156, 913–923. Author's personal copy 368 C. Soriano et al. / C. R. Palevol 9 (2010) 361–368 Martínez-Delclòs, X., Briggs, D.E.G., Peñalver, E., 2004. Taphonomy of insects in carbonates and amber. Palaeogeogr. Palaeoclimatol. Palaeoecol. 203, 19–64. Najarro, M., Peñalver, E., Rosales, I., Pérez-de la Fuente, R., Daviero-Gomez, V., Gomez, B., Delclòs, X., 2009. Unusual concentration of Early Albian arthropod-bearing amber in the Basque-Cantabrian Basin (El Soplao, Cantabria, Northern Spain): palaeoenvironmental and palaeobiological implications. Geologica Acta 7, 363–387. Néraudeau, D., Perrichot, V., Dejax, J., Masure, E., Nel, A., Philippe, M., Guillocheau, F., Guyot, T., 2002. Un nouveau gisement à ambre insectifère et à végétaux (Albien terminal probable : Archingeay, CharenteMaritime, France). Geobios 35, 233–240. Néraudeau, D., Allain, R., Perrichot, V., Videt, B., De Broin, F., Guillocheau, F., Philippe, M., Rage, J.C., Vullo, R., 2003. Découverte d’un dépôt paralique à bois fossiles, ambre insectifère et restes d’Iguanodontidae (Dinosauria, Ornithopoda) dans le Cénomanien inférieur de Fouras (Charente-Maritime, Sud-Ouest de la France). C. R. Palevol. 2, 221–230. Néraudeau, D., Vullo, R., Gomez, B., Perrichot, V., Videt, B., 2005. Stratigraphie et paléontologie (plantes, vertébrés) de la série paralique Albien terminal- Cénomanien basal de Tonnay-Charente (CharenteMaritime, France). C. R. Palevol. 4, 79–93. Néraudeau, D., Perrichot, V., Colin, J.P., Girard, V., Gomez, B., Guillocheau, F., Masure, E., Peyrot, D., Tostain, F., Videt, B., Vullo, R., 2008. A new amber deposit from the Cretaceous (Uppermost Albian-Lowermost Cenomanian) of southwestern France. Cretaceous Res. 29, 925–929. Néraudeau, D., Vullo, R., Gomez, B., Girard, V., Lak, M., Videt, B., Dépré, E., Perrichot, V., 2009. Amber, plant and vertebrate fossils from the Lower Cenomanian paralic facies of Aix Island (Charente-Maritime, SW France). Geodiversitas 31, 13–27. Ortega-Blanco, J., Peñalver, E., Delclòs, X., Engel, M.S. False fairy wasps in Early Cretaceous amber from Spain (Hymenoptera: Mymarommatoidea). Palaeontology (in press). Peñalver, E., Delclòs, X., Soriano, C., 2007. A new rich amber outcrop with palaeobiological inclusions in the Lower Cretaceous of Spain. Cretaceous Res. 28, 791–802. Penney, D., Dierick, M., Cnudde, V., Masschaele, B., Vlassenbroeck, J., van Hoorebeke, L., Jacobs, P., 2007. First fossil Micropholcommatidae (Araneae), imaged in Eocene Paris amber using X-ray computed tomography. Zootaxa 1623, 47–53. Perrichot, V., 2004. Early Cretaceous amber from south-western France: insight into the Mesozoic litter fauna. Geologica Acta 2, 9–22. Perrichot, V., Néraudeau, D., 2009. Foreword. Cretaceous ambers from southwestern France: geology, taphonomy and palaeontology. Geodiversitas 31, 7–12. Perrichot, V., Nel, A., Néraudeau, D., 2007. Schizopterid bugs (Insecta: Heteroptera) in mid-Cretaceous ambers from France and Myanmar (Burma). Palaeontology 50, 1367–1374. Perrichot, V., Marion, L., Néraudeau, D., Vullo, R., Tafforeau, P., 2008. The early evolution of feathers: fossil evidence from Cretaceous amber of France. P. Roy. Soc. Lond. B Bio. 275, 1197–1202. Perrichot, V., Néraudeau, D., Tafforeau, P., 2010. Charentese amber. In: Penney, D. (Ed.), Biodiversity of fossils in amber from the major world deposits. Siri Scientific Press, Manchester. Poinar, G.O., Hess, R., 1982. Ultrastructure of 40-million-years-old insect tissue. Science 215, 1241–1242. Schmidt, A.R., Ragazzi, E., Coppellotti, O., Roghi, G., 2006. A microworld in Triassic amber. Nature 444, 835. Tafforeau, P., Boistel, R., Boller, E., Bravin, A., Brunet, M., Chaimanee, Y., Cloetens, P., Feist, M., Hoszowska, J., Jaeger, J.J., Kay, R.F., Lazzari, V., Marivaux, L., Nel, A., Nemoz, C., Thibault, X., Vignaud, P., Zabler, S., 2006. Applications of X-ray synchrotron microtomography for nondestructive 3D studies of paleontological specimens. Appl. Phys. A Mater. 83, 195–202. Vršanský, P., 2009. Albian cockroaches (Insecta, Blattida) from French amber of Archingeay. Geodiversitas 31, 73–98.