Amber, a natural polymer, is fossil tree resin derived from diverse botanical sources with varying chemical compositions. As such, all amber is susceptible to the effects of light, temperature, relative humidity, and oxygen, as well as exposure to certain chemicals, and will deteriorate over time in collections if left unprotected. Here we review approaches for the conservation, preparation, and imaging of amber specimens and their inclusions, and address indications and causes of amber degradation, as well as recommendations for a suitable storage environment. We also provide updated preparation and embedding protocols, discuss several techniques for imaging inclusions, and address digitization efforts. A stable storage environment is essential to mitigate or avoid deterioration of amber, which often manifests as crazing, spalling, breaking and colour changes. Based on previous conservation studies of fossil resins, we generally recommend storage in a climate-monitored environment with a relative humidity of ca. 50%, 18 °C, and stress that light exposure must be kept to a minimum. For stabilization and anoxic sealing, amber specimens should ideally be embedded in an artificial epoxide resin (EpoTek 301-2 or similar is currently recommended). Amber should not be treated with or stored in vegetable or mineral oils (even for a short time for examination or photography), or come into contact with alcohol, disinfecting agents, hydrogen peroxide, or other destructive solvents or mixtures, since any of these materials can irreversibly damage the amber. Most photography of inclusions for research and digitization purposes can be successfully accomplished using light microscopy. Scanning electron microscopy (SEM) is sometimes used to uncover fine details, but is an invasive method. However, X-ray based methods (utilizing micro computed tomography, or micro-CT) are becoming more frequently used and increasingly indispensable in the examination of minute internal structures of inclusions, and to fully visualize important structures in opaque amber. Micro-CT makes it possible to digitize an inclusion three-dimensionally, and thus enables digital specimen 'loans'. Light microscopal images are still widely used in the digitization of amber specimens and are an essential alternative to micro-CT imaging when resources or time are limited. Overall, due to the vulnerability of all fossil resins, we recommend that conservation of amber samples and their inclusions be prioritized.
Research Article| January 01, 2009 Exceptional preservation of marine diatoms in upper Albian amber Vincent Girard; Vincent Girard * 1Université Rennes 1, UMR CNRS 6118, Rennes 35042, France *E-mail: vincent.girard@univ-rennes1.fr. Search for other works by this author on: GSW Google Scholar Simona Saint Martin; Simona Saint Martin 2Muséum National d'Histoire Naturelle, UMR CNRS 5143, Paris 75231, France 3Universitatea din Bucureşti, Facultatea de Geologie şi Geofizică, Bucarest 020956, Romania Search for other works by this author on: GSW Google Scholar Jean-Paul Saint Martin; Jean-Paul Saint Martin 2Muséum National d'Histoire Naturelle, UMR CNRS 5143, Paris 75231, France Search for other works by this author on: GSW Google Scholar Alexander R. Schmidt; Alexander R. Schmidt 4Georg-August-Universität Göttingen, Courant Research Centre Geobiology, Göttingen 37077, Germany Search for other works by this author on: GSW Google Scholar Steffi Struwe; Steffi Struwe 5Museum für Naturkunde der Humboldt-Universität zu Berlin, Berlin 10115, Germany Search for other works by this author on: GSW Google Scholar Vincent Perrichot; Vincent Perrichot 6University of Kansas, Paleontological Institute, Lawrence, Kansas 66045, USA Search for other works by this author on: GSW Google Scholar Gérard Breton; Gérard Breton 1Université Rennes 1, UMR CNRS 6118, Rennes 35042, France Search for other works by this author on: GSW Google Scholar Didier Néraudeau Didier Néraudeau 1Université Rennes 1, UMR CNRS 6118, Rennes 35042, France Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (1): 83–86. https://doi.org/10.1130/G25009A.1 Article history received: 10 Apr 2008 rev-recd: 17 Sep 2008 accepted: 22 Sep 2008 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Vincent Girard, Simona Saint Martin, Jean-Paul Saint Martin, Alexander R. Schmidt, Steffi Struwe, Vincent Perrichot, Gérard Breton, Didier Néraudeau; Exceptional preservation of marine diatoms in upper Albian amber. Geology 2009;; 37 (1): 83–86. doi: https://doi.org/10.1130/G25009A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Late Albian amber from Charente-Maritime (southwestern France) contains the first known marine diatoms preserved in a fossil resin. Approximately 70 inclusions were assignable to the genera Basilicostephanus, Coscinodiscus, Hemiaulus, Melosira, Paralia, Skeletonema, Stephanopyxis, Trochosira, ?Aulacoseira, and to the order Rhizosoleniales. Some of them are represented by several species. This diatom assemblage is mainly composed of colonial planktonic genera, which are typical for coastal shallow waters. The newly found amber inclusions extend the fossil record of four genera and one order from the Late Cretaceous and support certain molecular phylogenetic assumptions regarding the diversification of marine diatoms in the Early Cretaceous. The unusual introduction of diatom shells from the beach or sea by wind, spray, or high tide onto the resin flows was possible because the amber forest grew close to the seashore. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
The occurrence of arthropods in amber exclusively from the Cretaceous and Cenozoic is widely regarded to be a result of the production and preservation of large amounts of tree resin beginning ca. 130 million years (Ma) ago. Abundant 230 million-year-old amber from the Late Triassic (Carnian) of northeastern Italy has previously yielded myriad microorganisms, but we report here that it also preserves arthropods some 100 Ma older than the earliest prior records in amber. The Triassic specimens are a nematoceran fly (Diptera) and two disparate species of mites, Triasacarus fedelei gen. et sp. nov., and Ampezzoa triassica gen. et sp. nov. These mites are the oldest definitive fossils of a group, the Eriophyoidea, which includes the gall mites and comprises at least 3,500 Recent species, 97% of which feed on angiosperms and represents one of the most specialized lineages of phytophagous arthropods. Antiquity of the gall mites in much their extant form was unexpected, particularly with the Triassic species already having many of their present-day features (such as only two pairs of legs); further, it establishes conifer feeding as an ancestral trait. Feeding by the fossil mites may have contributed to the formation of the amber droplets, but we find that the abundance of amber during the Carnian ( ca. 230 Ma) is globally anomalous for the pre-Cretaceous and may, alternatively, be related to paleoclimate. Further recovery of arthropods in Carnian-aged amber is promising and will have profound implications for understanding the evolution of terrestrial members of the most diverse phylum of organisms.
Abstract. Agaricomycetes are major components of extant terrestrial ecosystems; however, their fruiting bodies are exceedingly rare as fossils. Reinvestigation of a peculiar fossil from Late Triassic sediments of southern Germany interpreted as a bracket fungus revealed that this fossil in fact represents a wood abnormality, resulting from injury to the cambium and subsequent callus growth in a Baieroxylon -like ginkgoalean wood. As a result, the fossil record of the Agaricomycetes does not yet pre-date the Early Cretaceous, suggesting a late diversification of basidiomycetes possessing large fruiting bodies.
The Carnian Pluvial Episode (CPE) has been recognized as a time of plant radiations and originations, likely related to observed swift changes from xerophytic to more hygrophytic floras. This suggests that the increasing humidity causally resulting from LIP volcanism was the trigger for these changes in the terrestrial realm. Understanding the cause and effects of the CPE on the plant realm, requires study of well-preserved floras that are precisely aligned with the CPE. We therefore focus on the best age-constrained section within the CPE for the terrestrial to marginal marine environment to understand the floristic composition at the early CPE. This is found in the Dolomites, Italy, and is remarkable for the preservation of the oldest fossiliferous amber found in the rock record. An integrated study of palynomorphs and macro-remains related to the conifer families of the fossil resin bearing level brings together the floral components from this section. This observed mixture of different taxa of extinct and modern conifer families underlines firmly the effects of the LIP-induced CPE on the evolution and radiation of conifers.
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