Protist-like inclusions in amber, as evidenced by Charentes amber

The mid-Cretaceous amber of France contains thousands of protist-like inclusions similar in shape to some ciliates, flagellates and amoebae. The sheer abundance of these inclusions and their size variation within a single amber piece are not concordant with true fossil protists. French amber is coniferous in origin, which generally does not preserve well protists without cell walls. Thus, it would be surprising if French Cretaceous amber had preserved millions of protists. Here, we present a survey of the protist-like inclusions from French amber and attempt to elucidate their origins.Diverse Cretaceous ambers (from Spain, Germany and Lebanon), also derived from conifer resins, contain thousands of protist-like inclusions. In contrast, Tertiary ambers and modern resins are poor in protist-like fossils. This suggests these inclusions originated from early Cretaceous plant resins, probably secreted with the resin by trees that did not survive after the Cretaceous (such as the Cheirolepidiaceae). A review of the recent literature on amber microfossils indicates several protist-like inclusions that are unlikely to have a biological origin have already been described as real fossil protists. This is problematic in that it will bias our understanding of protist evolution.     

Insect outbreaks produce distinctive carbon isotope signatures in defensive resins and fossiliferous ambers

Despite centuries of research addressing amber and its various inclusions, relatively little is known about the specific events having stimulated the production of geologically relevant volumes of plant resin, ultimately yielding amber deposits. Although numerous hypotheses have invoked the role of insects, to date these have proven difficult to test. Here, we use the current mountain pine beetle outbreak in western Canada as an analogy for the effects of infestation on the stable isotopic composition of carbon in resins. We show that infestation results in a rapid (approx. 1 year) (13)C enrichment of fresh lodgepole pine resins, in a pattern directly comparable with that observed in resins collected from uninfested trees subjected to water stress. Furthermore, resin isotopic values are shown to track both the progression of infestation and instances of recovery. These findings can be extended to fossil resins, including Miocene amber from the Dominican Republic and Late Cretaceous New Jersey amber, revealing similar carbon-isotopic patterns between visually clean ambers and those associated with the attack of wood-boring insects. Plant exudate δ(13)C values constitute a sensitive monitor of ecological stress in both modern and ancient forest ecosystems, and provide considerable insight concerning the genesis of amber in the geological record.     

Arthropods in contemporary and some fossil resins

More than 4800 arthropod inclusions were isolated and identified from resin of various contemporary conifer trees in various parts of northern Eurasia. Their composition is compared with that in representative collections of Baltic and Rovno ambers (Upper Eocene) and with that in Dominican amber (Lower Miocene). The original composition of inclusions of Dominican amber is reconstructed for the first time using a procedure intended to reduce the effect of human bias. Taphonomical characteristics of resins and their effects on the composition of inclusions are studied. The actuapaleontological approach reveals a trend towards a decrease in the relative abundance of arboreal springtails and nematoceran dipterans and an increase in that of the true bugs, beetles, lepidopterans, and hymenopterans (especially ants) between the Eocene and the present. Relative abundances of spiders and mites show no clear trend. The available data on other arthropods are still insufficient for elucidating evolutionary trends. Surprisingly, a small contemporary sample from Taimyr (N. Siberia) was inexplicably more similar to the Eocene amber than to other contemporary resins. No other significant differences in composition of inclusions, compared across different conifer genera or geographic areas, have been revealed. A more detailed comparison between contemporary and fossil hymenopteran and beetle inclusions reveals correlations with both age (= evolutionary change) and geography. The absolute dominance of ants, particularly Formicinae and Myrmicinae, and, among solitary hymenopterans, Ichneumonidae, Braconidae, and Pteromalidae, and a corresponding decline in the abundance of Scelionidae and Dolichoderinae in contemporary resins compared to amber reflect evolutionary changes. In contrast, the overwhelming abundance of Formicinae and consistent occurrence of sawflies in contemporary resins of northern Eurasia appear to be explained by geography. The Eocene assemblages of beetle inclusions are characterized by a wider and more variable set of dominant families, in sharp contrast to contemporary resins, which are uniformly dominated by Curculionidae, Chrysomelidae, and Staphylinidae. Additional analyses are needed to explain this difference.     

Microbe‐like inclusions in tree resins and implications for the fossil record of protists in amber

During the past two decades, a plethora of fossil micro‐organisms have been described from various Triassic to Miocene ambers. However, in addition to entrapped microbes, ambers commonly contain microscopic inclusions that sometimes resemble amoebae, ciliates, microfungi, and unicellular algae in size and shape, but do not provide further diagnostic features thereof. For a better assessment of the actual fossil record of unicellular eukaryotes in amber, we studied equivalent inclusions in modern resin of the Araucariaceae; this conifer family comprises important amber‐producers in Earth history. Using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS), we investigated the chemical nature of the inclusion matter and the resin matrix. Whereas the matrix, as expected, showed a more hydrocarbon/aromatic‐dominated composition, the inclusions contain abundant salt ions and polar organics. However, the absence of signals characteristic for cellular biomass, namely distinctive proteinaceous amino acids and lipid moieties, indicates that the inclusions do not contain microbial cellular matter but salts and hydrophilic organic substances that probably derived from the plant itself. Rather than representing protists or their remains, these microbe‐like inclusions, for which we propose the term ‘pseudoinclusions’, consist of compounds that are immiscible with the terpenoid resin matrix and were probably secreted in small amounts together with the actual resin by the plant tissue. Consequently, reports of protists from amber that are only based on the similarity of the overall shape and size to extant taxa, but do not provide relevant features at light‐microscopical and ultrastructural level, cannot be accepted as unambiguous fossil evidence for these particular groups.     

Enantiomeric composition and prevalence of some bicyclic monoterpenoids in amber

Among the more prevalent chiral monoterpenoid compounds in conifers are α-pinene, β-pinene, and smaller amounts of camphene and limonene. The most prevalent chiral monoterpenoid compounds in fossilized resin (referred to as amber in this paper) appear to be borneol, isoborneol, and camphene. Most of these compounds have easily measured enantiomeric excesses. The borneol and isoborneol in some amber samples have pronounced enantiomeric excesses despite the fact that they are tens of millions of years old. The enantiomeric ratios of the monoterpenoids in different ambers vary tremendously and often are distinct. However, in any single amber sample, the stereochemistry (absolute configuration) of the excess monoterpenoid enantiomers appears to be identical. The camphene in amber may be a secondary reaction product formed over time, possibly from the dehydration of borneol. Although a compound's original stereochemistry can be preserved, it also may diminish with the number and type of chemical transformations over geological time. The monoterpene enantiomeric ratios in modern conifer resins vary tremendously. Future stereochemical studies are outlined that could provide the data necessary for more exact geochemical interpretations and possibly for obtaining pertinent paleobiological information. © 1996 Wiley-Liss, Inc.     

First record of Pliensbachian (Lower Jurassic) amber and associated palynoflora from the Monti Lessini (northern Italy)

The fossil record of amber dates back to the Palaeozoic, but it is only since the Mesozoic that amber became relatively common, probably because of the spreading of resin-producing plants. In Italy, the oldest ambers come from the Middle and Upper Triassic of the Dolomites. Cretaceous ambers come from some Albian sites in the Dolomites and from the Coniacian–Santonian of Vernasso, Julian Prealps, northern Italy. Until now, no Jurassic sites with amber have been reported in Italy, and this “Jurassic gap” seems generalized, since there are only a few Jurassic ambers described all over the world. Here, we report the first finding of Lower Jurassic (Pliensbachian) amber from the Bellori locality (Grezzana, Verona Province, Northern Italy). The amber was found in two clayey-coal levels containing plant remains and cuticles, with subordinate bivalves, foraminifera and ostracods. Palynomorphs of the amber levels are dominated by levigate and ornamented spores (ferns) and Circumpolles (conifers). Foraminiferal linings and algal cysts are also present. The freshwater alga Pseudoschizaea is reported for the first time from the Lower Jurassic. The amber shows different kinds of preservation, some peculiar features probably connected with the plant structure, and colours ranging from light yellow to blackish red. Moreover, it includes millimetre-sized wood structures (“mummified wood”) and gas bubbles. Fourier-transform–Infrared, thermogravimetric and differential thermogravimetric analyses were carried out and resulted in a clear characterization of this amber with respect to all others known so far. These data, together with sedimentological observations and fossil content analysis, suggest a coastal palaeoenvironment under rather wet conditions, comparable with the present-day Everglades, with the addition of a monsoonal climate as in the modern southern Asia.     

Miocene Ethiopian amber: A new source of fossil cryptogams

Amber is renowned for the exceptional preservation state of its inclusions, allowing detailed morphological analysis and providing relevant environmental, palaeoecological, geographical, and geological information. Amber deposits are predominantly known from North America, Europe, and Asia, and are considered to be rare on the continents that formed Gondwana. The recent discovery of fossiliferous amber deposits in Ethiopia, therefore, provides an inimitable opportunity to close gaps in the fossil record of African terrestrial biota and to study organisms which are otherwise rare in the fossil record. Here we show that diverse cryptogams are preserved in highest fidelity in Miocene Ethiopian amber. We describe gametophyte fragments of four liverworts: Thysananthus aethiopicus sp. nov. (Porellales, Lejeuneaceae), Lejeunea abyssinicoides sp. nov. (Porellales, Lejeuneaceae), Frullania shewanensis sp. nov. (Porellales, Frullaniaceae), and Frullania palaeoafricana sp. nov. (Porellales, Frullaniaceae). Furthermore, we describe a pleurocarpous moss of the extant genus Isopterygium (Hypnales, Pylaisiadelphaceae) and a lichen representing the order Lecanorales. These new specimens represent the first amber fossils of liverworts, mosses, and lichens from the African continent and render Ethiopian amber as one of the few worldwide amber deposits preserving bryophytes (mosses and liverworts) or lichens. Fossil species of Thysananthus were recorded in Eocene Baltic and Oligocene Bitterfeld as well as Miocene Dominican and probably also Miocene Mexican ambers. Fossils that can unequivocally be assigned to Lejeunea have only been found in Dominican amber so far. Neotropical ambers contain only one taxon of Frullania to date, while the genus is most diverse in Baltic, Bitterfeld, and Rovno ambers, formed in temperate regions. The new fossils support a tropical to subtropical origin of Ethiopian amber. The new African liverwort fossils are included in an updated list of leafy liverworts described from worldwide Cenozoic ambers to date.     

缅甸琥珀内含物形态结构在X射线下的可辨识性

【目的】产自缅甸北部胡康河谷的缅甸琥珀形成于白垩纪中期。其艺术价值很高,同时其内含物的生物多样性程度也很高,故其科学价值也不可估量。显微CT能够提供化石(琥珀)内部解剖结构的高分辨率断层图像,故该方法日渐成为目前琥珀研究中的常用方法之一。然而在可见光下可见的琥珀内的生物结构,在X射线下却有不同的结果,这与现生研究材料在显微CT下的表现非常不同。本研究对产自胡康河谷的9块缅甸琥珀进行显微CT检测,试图对这个特殊的现象进行较为系统的解读。【方法】利用数码相机(Nikon 5200D)拍摄琥珀照片,并用Helicon Focus 5.3软件合成。通过显微CT技术扫描琥珀和计算机断层重建技术重建出缅甸琥珀内含物的三维结构形态。【结果】显微CT检测结果主要分为3种:完全无衬度、部分结构有衬度和整体结构有较好衬度。本研究对有较好衬度的琥珀内含物进行了三维重建,展示了琥珀内含物的外部和内部三维结构。【结论】琥珀内含物的可见光成像和X射线成像不存在一一对应关系,其原因和琥珀保存的好坏以及琥珀的密度差、琥珀围岩之间的对比度差异有关。琥珀形成和埋藏过程中的物理和化学变化非常复杂,其机理的探究也更为复杂和困难,本文对这个现象的主要类型做了较为初步的阐述,后续研究需要更为全面的选样和更为严格的实验设计才能够最终解决这个埋藏学上的难题。     

白垩纪缅甸琥珀中小型花蚤一新种(鞘翅目: 花蚤科) 及对花蚤科的分类学修订

根据产自缅甸北部白垩纪中期克钦琥珀中的一块小型花蚤化石标本,建立1新种——小多刺花蚤(Multispinus parvus sp. nov.),归于花蚤科(Mordellidae)。同时,对缅甸琥珀中已发现的花蚤和泛花蚤进行了重新观察和研究,重点分析了其形态学特征并认真考虑了相关分类学依据,将短尾花蚤科(Apotomouridae)修订为花蚤科之下的短尾花蚤亚科(Mordellidae:Apotomourinae)。短尾花蚤中普遍存在的臀锥完全不发育,不可作为区分于花蚤科的衍征。白垩纪中期琥珀中发现的花蚤化石类群体型均小,这也许与白垩纪中期生态环境和栖息地被子植物花朵形态有关。     

FOSSIL OONOPID SPIDERS IN CRETACEOUS AMBERS FROM CANADA AND MYANMAR

Abstract:  The spider family Oonopidae is described from Cretaceous ambers from Myanmar and Canada for the first time. Orchestina albertenis sp. nov. is the first spider to be described from Canadian Grassy Lake amber and only the second spider to be described from Canadian amber. The specimen in amber from Myanmar extends the known range of the extant genus Orchestina back another 10 million years from the previously oldest specimen in Turonian New Jersey amber. Despite being unknown as sedimentary fossils, Oonopidae occur in more fossil deposits than any other spider family and were already widespread by the Cretaceous. The family contains the oldest example of an extant spider genus along with Archaeidae, also from Burmese amber.     

L’ambre albo-cénomanien de la montagne de Lure (Alpes-de-Haute-Provence), outil stratigraphique et paléogéographique

Nodules of fossil resin or amber, first drifted and then deposited in the marine series with cephalopods, were discovered in several areas of High-Provence, in geological series of the Cretaceous system. These areas are located around the Mountain of Lure; amber nodules have been found in the upper Albian (Ongles, Revest-des-Brousses) and in the lower Cenomanian (Saint-Étienne-les-Orgues, Aubignosc and Salignac). These ambers have very homogeneous and characteristic FTIR spectra, making it possible to distinguish them not only from more recent ambers of the upper Cretaceous of Provence (Santonian), but also from tertiary ambers of the Baltic sea. These organic matters in marine environment, brought by the currents and deposited in shallow waters of the Ventoux-Lure area, are in agreement with close emerged grounds, which were set up by the Albo-Cenomanian tectonic movements.     

Thrips (Thysanoptera, Insecta) from the Rovno amber, Eocene of Ukraine

Seventy-six thrips were discovered in Rovno amber. Among these, 67 were identified to suborder, 52, to family, 45, to genus, and 41, to species level. In total, five species, six genera, five families, and two suborders are recorded. No undescribed taxa have been found so far. All the identified thrips, except those of the genus Phloeothrips, belong to fossil taxa, previously known only from the Baltic and Bitterfeld ambers. However, the composition of species in the Rovno amber is highly unusual due to domination of Praedendrothrips avus Priesner, 1924. This species, rare in the Baltic amber, constitutes 49% of all the Rovno records. Thus, the Rovno amber, in contrast to the Baltic and Bitterfeld ambers, is characterized by poor taxonomic diversity of thrips and presence of a clearly dominant species.     

Streptomycin-Induced Phenotypic Suppression of Hydroxylamine-Induced Nonsense Mutants in the rII A Cistron of Bacteriophage T4

Twenty-one hydroxylamine-induced rII A cistron nonsense mutants were tested for streptomycin (SM)-induced phenotypic suppression by exposing Escherichia coli SBO (nonpermissive host) to phage in the presence and absence of SM. All nine amber, four of six ochre, and five of six opal mutants were phenotypically suppressible by SM. For suppressible mutants, the ratio of the average burst size in the presence of SM to size in the absence of SM ranged from 12 to 242 for the ambers, 3 to 33 for the ochres, and 4 to 14 for the opals. Increased susceptibility of the amber mutants to SM-induced phenotypic suppression relative to the susceptibility of the opal and ochre mutants may reflect a neighboring base effect, such that a 3′-terminal adenine inhibits misreading of a 5′-terminal uracil.     

Eohelea sinuosa (Meunier, 1904) (Diptera, Ceratopogonidae) in Late Eocene ambers of Europe

Differences between ceratopogonid faunas from different Late Eocene ambers are almost as great as between ant faunas and give evidence of their different geographical origins. The greatest similarity is recorded between ceratopogonid faunas of the Rovno and Danish ambers; it manifests itself, in particular, in the presence of Leptoconops, abundant Eohelea sinuosa, and rather frequent occurrence of Meunierohelea. Eohelea sinuosa is the most abundant ceratopogonid species in the Rovno amber. The abundance of Eohelea is probably accounted for by the abundance in these assemblages of small chironomids, with terrestrial larvae; which composed 40% of the Rovno amber chironomid fauna and were probably prey to Eohelea. It is shown for the first time that Ceratopogonini with feminized male antennae (with reduced plume) occur three times as often in syninclusions of specimens of both sexes (63% of all Eohelea inclusions from the Rovno amber);this is evidence that Ceratopogonini with feminized male antennae turned to mating on substrate. This supports the hypothesis of Dinwiddie and Rachootin (2011) that wing organs of female Eohelea were not used for stridulation.     

Miocene spiders in Dominican amber (Oonopidae,Mysmenidae)

Oonops seldeni sp. nov. and Mysmenopsis lissycoleyae sp. nov. are described from male specimens preserved in Miocene amber from the Dominican Republic and are the first fossil records of these extant genera. Gamasomorpha incerta Wunderlich, 1988 is transferred to Stenoonops. Two females previously described as Orchestina dominicana? Wunderlich, 1981 are transferred to Orchestina sp. indet., and one new specimen of a male of Orchestina dominicana Wunderlich, 1988 is identified. Oonopidae is reported for the first time from Cretaceous ambers of Burma, Lebanon and New Jersey. These are the oldest records of this family, extending the known range from the Rupelian (Oligocene) to the Valanginian (Lower Cretaceous). Recent StenoonopsMysmenopsis are unknown from Hispaniola. The presence of these genera in amber suggests that they will be found. The presence of Mysmenopsis in amber is further evidence of kleptoparasitic/commensal spiders in the Miocene.     

First Record of the Late Eocene Ichneumon Fly <Emphasis Type="Italic">Rasnitsynites tarsalis</Emphasis> Kasparyan (Ichneumonidae,Townesitinae) in Ukraine Confirms Correlation of the Upper Eocene Lagerstätten

Rasnitsynites tarsalis Kasparyan (Ichneumonidae, Townesitinae) described from the Baltic amber is recorded for the first time in the Rovno amber (Gulyanka, Zhitomir Region); therefore, this is the southernmost and easternmost find of Townesitinae. The presence of numerous extinct taxa of Townesitinae and tribes of Hybrizoninae Blanchard 1845 = Paxylommatinae Förster, 1862 = Hybrizontinae Marshall, 1872 confirms close relation of the Bembridge Marls fauna (Upper Eocene of England) and that of the succinites (Baltic, Rovno, and other Late Eocene European ambers); they are common in the succinites and in the Bembridge Marls and are only known from these localities.     

Review of the Late Eocene Encyrtidae (Hymenoptera,Chalcidoidea) with a description of the first fossil genus with filum spinosum

Glaesus gibsoni gen. et sp. nov. and Eocencnemus gedanicus sp. nov. are described from materials stored in the amber collection of the University of Gdańsk. Eocencyrtus zerovae Simutnik, 2001 is for the first time recorded in the Baltic amber. The encyrtids recorded in Eocene ambers are reviewed, and a key to the known genera is given. The fossil Encyrtidae cannot be placed with confidence in any of the established subfamilies. Their comparative morphology is analyzed. One of the diagnostic characters of the subfamily Encyrtinae, the presence of the filum spinosum, is recorded for the first time for fossil encyrtids (in G. gibsoni).     

Exquisite preservation of a widespread filamentous microorganism in French Cretaceous ambers: Crucial for revising a controversial fossil

Cretaceous ambers from different localities often contain abundant filamentous microorganisms that extend from the surface of the lumps of amber towards their center. These microfossils have been interpreted in the past as sheathed bacteria, cyanobacteria, and fungal hyphae, respectively. Here, we applied various techniques such as optical microscopy, confocal microscopy, and SEM to constrain the actual nature of these microorganisms. We evaluate published views and new evidence and conclude that the observed morphological and ultrastructural features correspond to sheathed bacteria. We propose a scenario explaining the observed differential preservations as various stages of the sheath construction around the bacterial filaments growing in the resin and the consequences of the transformation of the resin to amber. We suggest an abundant occurrence of at least one extinct resinicolous Leptothrix-like taxon in the Cretaceous Period.     

<Emphasis Type="Italic">Protocopidosoma</Emphasis> gen. nov. (Hymenoptera,Chalcidoidea, Encyrtidae) from the Late Eocene Danish amber

Protocopidosoma kononovae gen. et sp. nov. from Danish amber is described. The specimen is very similar to representatives of the extant genus Copidosoma Ratzeburg, 1844 and differs from them in the long and wide veins in the forewing, as in most encyrtids from Late Eocene European ambers.