Amber Inclusions Research Articles

Diversity of Eocene Ripiphoridae with descriptions of the first species of Pelecotominae and larva of Ripidiinae (Coleoptera)

AbstractThe Eocene records of the beetle family Ripiphoridae are evaluated and summarized. A new species of Pelecotominae belonging to the genus Clinops, C. svachaisp. nov. from Baltic amber, is described and figured. The female holotype of C. svachai is the first Palaeogene member of this subfamily to be identified. In addition, a male of a different unidentified genus of Pelecotominae, preserved as an inclusion in Baltic amber, is documented. The first Palaeogene primary larva of Ripiphoridae is described from Sakhalin amber and is compared with all other primary larvae of this family. The larva is attributed to Ripidius (Ripidiinae) and bears some unique characters absent in larvae of this extant genus. A putative record of Ripiphorus (Ripiphorinae) in the Berendt collection is identified as a member of Ripidius. Distribution of Eocene species are compared with those of their closest extant relatives and mapped. Based on the fossil record and the distribution of extant South African species of Clinops, this genus is tentatively thought to be an example of an Eocene relict, while the extant pelecotomine genus Scotoscopus from the East Mediterranean is considered to be an Oligocene–Miocene relict as its distribution corresponds with the geological history of the Aegais landmass.

New Data on Ichneumon Wasps of the Subfamily Pherhombinae (Hymenoptera, Ichneumonidae) in Baltic Amber with Descriptions of Three New Species

Three new fossil species of the subfamily Pherhombinae (Hymenoptera, Ichneumonidae) are described from Primorskoe deposit of Eocene Baltic amber (Kaliningrad Province, Russian Federation): Pherhombus kasparyanisp. n., Ph. kraxtepellensissp. n., and Ph. sorgenauensissp. n. An annotated list and a key to the six known species of Pherhombinae are given. The color preservation of ichneumonid inclusions in Baltic amber is discussed, the presence of syninclusions is interpreted, and reconstruction of the species biology is attempted.

Mid-Cretaceous amber inclusions reveal morphogenesis of extinct rachis-dominated feathers

We describe three-dimensionally preserved feathers in mid-Cretaceous Burmese amber that share macro-morphological similarities (e.g., proportionally wide rachis with a “medial stripe”) with lithic, two-dimensionally preserved rachis-dominated feathers, first recognized in the Jehol Biota. These feathers in amber reveal a unique ventrally concave and dorsoventrally thin rachis, and a dorsal groove (sometimes pigmented) that we identify as the “medial stripe” visible in many rachis-dominated rectrices of Mesozoic birds. The distally pennaceous portion of these feathers shows differentiated proximal and distal barbules, the latter with hooklets forming interlocking barbs. Micro-CT scans and transverse sections demonstrate the absence of histodifferentiated cortex and medullary pith of the rachis and barb rami. The highly differentiated barbules combined with the lack of obvious histodifferentiation of the barb rami or rachis suggests that these feathers could have been formed without the full suite and developmental interplay of intermediate filament alpha keratins and corneous beta-proteins that is employed in the cornification process of modern feathers. This study thus highlights how the development of these feathers might have differed from that of their modern counterparts, namely in the morphogenesis of the ventral components of the rachis and barb rami. We suggest that the concave ventral surface of the rachis of these Cretaceous feathers is not homologous with the ventral groove of modern rachises. Our study of these Burmese feathers also confirms previous claims, based on two-dimensional fossils, that they correspond to an extinct morphotype and it cautions about the common practice of extrapolating developmental aspects (and mechanical attributes) of modern feathers to those of stem birds (and their dinosaurian outgroups) because the latter need not to have developed through identical pathways.

On the first <i>Silis</i> Charpentier, 1825 from Baltic amber (Coleoptera, Cantharidae)

Abstract. Only in recent years have new genera and species of the subfamily Silinae Mulsant, 1862 been described as inclusions in amber. However, no representative of the genus Silis Charpentier, 1825 had been described from Baltic amber, even if few specimens were already known at the generic level. Silis lombardii sp. nov. is entirely dark brown and shows (as usual for the genus) the two characteristic lobes in the sides of pronotum, elongated elytra, and a basal small tooth only on the anterior claws. The Eocene findings show that the subfamily is of ancient origin and that at least in the Eocene it was much more abundant than today in the same territories, where only two species are known. (urn:lsid:zoobank.org:act:76887127-3D24-41DA-86CC-7DCAB40DC3B7)

Notes on mid-Cretaceous †Pangusyndicus and its relatives, with description of †Loeblitoides gen. nov. and a †Nuegua-like new species (Coleoptera: Staphylinidae: Scydmaeninae)

Two new species of Cenomanian Glandulariini are described, based on inclusions in Burmese amber: †Loeblitoides separatus gen. et sp. nov., and †Pangusyndicus longirostris sp. nov. A new specimen of an unnamed species of †Nuegua Yin et al. is recorded from the same deposit and illustrated for comparative purposes. †Loeblitoides is morphologically close to †Pangusyndicus, but has more plesiomorphic antennae, with the antennomere 11 distinctly smaller than 10, but fully demarcated by a constriction (antennomere 10 is not subcylindrical as in †Pangusyndicus, but fusiform). †Pangusyndicus longirostris, in turn, is unusual in having an elongated pre-ocular region of the head, resembling the condition known so far only in †Nuegua. Morphological affinities between these genera strongly suggest their close relationships. The previously postulated hypothesis of a close relationship between †Pangusyndicus and the extant Syndicus (and its closest relatives) is discussed as poorly supported, as these taxa, despite having similar antennal structure, differ in many important characters. In order to verify this issue, much dense taxon sampling (i.e., inclusion of at least most of extant genera and subgenera of Glandulariini) is required, as this is the largest and taxonomically most challenging tribe of Scydmaeninae, with still largely unknown relationships between extant taxa.

†Rovnoleptochromus balticus sp. nov., a New Upper Eocene Ant-Like Stone Beetle

A leptochromine ant-like stone beetle, †Rovnoleptochromus balticussp. nov., is described, based on an exquisitely preserved inclusion in Upper Eocene Baltic amber from Kaliningrad Region. The holotype specimen reveals novel characters, not observed (presumably because of poorer preservation) in the previously known †R. ableptonoides Jaloszynski & Perkovsky of Rovno, Ukraine: three pairs of thick, long setae on the head (on vertex, near each eye and near each antennal insertion). Similar, presumably sensory structures (sensilla chaetica), are known in extant and extinct (Upper Cretaceous) Leptomastacini and the enigmatic Upper Cretaceous †Palaeoleptochromus O'Keefe. However, in these taxa, at most two pairs occur. The new finding broadens the known distribution of †Rovnoleptochromus during the Eocene, and suggests that the paired sensory bristles on the head may represent an ancestral condition in at least some of the tribes currently included in Mastigitae, which have later been partly or completely reduced in most members of this group.

Amber.

David Grimaldi introduces amber and the fossils contained therein.

Celebrating Research Devoted to Seed‐Free Land Plants

Celebrating Research Devoted to Seed‐Free Land Plants

<p><strong>Fossils X3 for the 8<sup>th</sup> time and IPS Meeting in Santo Domingo, April 2019</strong></p>

The Fossil Insect Network was created 33 years ago in 1996 in Strasbourg, France, under the auspices of the European Science Foundation. Since then, several meetings were organised: 1998—First International Palaeoentomological Conference in Moscow, Russia; 1998—World Congress on Amber Inclusions in Vitoria-Gasteiz, Basque Country, Spain; 2000—Brazilian Symposium on Palaeoarthropodology in Ribeirão Preto, Brazil; 2001—Second International Congress on Palaeoentomology, Fossil Insects, Kraków, Poland. This Congress in Kraków was also the origination of the International Palaeoentomological Society. The year 2005 was very important as three meetings, i.e. the Palaeoentomological Conference, the World Congress on Amber Inclusions, and the International Meeting on Palaeoarthropodology were decided to merge together as Fossils X3. This decision was made in Pretoria, South Africa. Following the International Congresses on Fossil Insects, Arthropods and Amber, Fossils X3 continued in 2007—Vitoria-Gasteiz, Basque Country, Spain, 2010; in Beijing, China, 2013—Byblos, Lebanon; and 2016—Edinburgh, Scotland, where ‘International Fossil Insects Day’ was declared and is now celebrated on each 1st of October.

Total‐evidence approach reveals an extinct lineage of Paederinae rove beetles from Cretaceous Burmese amber

AbstractThe fossil record contains vital information about the evolution of lineages and is a source of data that cannot be reconciled other than by the direct observation of morphologies. Total‐evidence phylogenetic reconstruction is being increasingly used to assess the position of extinct taxa by incorporating morphological data from extinct and extant taxa together with molecular data from extant taxa in a united framework. Here we apply the method to two Cretaceous Burmese amber inclusions belonging to the rove beetle subfamily Paederinae. To perform the total evidence analysis, we constructed the first morphological matrix and the most comprehensive molecular dataset for the subfamily. Our analysis reveals an extinct lineage of Paederinae rove beetles with a suite of unique morphological characters, resulting in the description of a new genus: Diminudon gen. nov. and two new species: D. schomannae sp. nov. and D. kachinensis sp. nov. Simultaneously our analyses provide new insights into the evolution and classification of the entire subfamily. We also discuss the unusually small size of the newly described Paederinae, which may represent an additional case for miniaturization in the Cretaceous.

The discovery of Burmolycus compactus gen. et sp. nov. from the mid-Cretaceous of Myanmar provides the evidence for early diversification of net-winged beetles (Coleoptera, Lycidae)

A new net-winged beetle, Burmolycus compactus gen. et sp. nov. (Coleoptera, Elateroidea, Lycidae), is described from mid-Cretaceous Burmese amber and the new tribe Burmolycini trib. nov. is erected for this species in Dexorinae Bocak et Bocakova, 1989. B. compactus is the oldest amber inclusion of a net-winged beetle. The discovery suggests the start of Lycidae diversification at least in the Mid-Cretaceous. The fossil was discovered in the area of the highest phylogenetic diversity of extant net-winged beetles, in deposits with a rich beetles fauna. The species is a member of the putative early radiation of this family and shows relationships with Afrotropical Dexorinae from which it differs in the dilated apical palpomeres, serrate antennae, and fully metamorphosed females. Burmolycus compactus shares 10-segmented antennae with several genera with proved or hypothesized neotenic females. The general appearance of Cretaceous B. compactus is surprisingly similar to extant net-winged beetles and may represent the example of their long-term morphological stasis.

A new genus and species of thorny lacewing from Upper Cretaceous Kuji amber, northeastern Japan (Neuroptera, Rhachiberothidae).

Kujiberothateruyukiigen. et sp. n., a remarkable new genus and species of Rhachiberothidae, is described from Upper Cretaceous amber from the Kuji area in northeastern Japan. This discovery represents the first record of this family both from Japan and from East Asia. This fossil taxon has the largest foreleg in the subfamily Paraberothinae found to date and its discovery implies that this group had higher morphological diversity in the Cretaceous than it does now. This finding also stresses the importance of the insect inclusions in Kuji amber, which have not been well explored in spite of their potential abundance.

Synchrotron X-ray imaging of a dichasium cupule of Castanopsis from Eocene Baltic amber.

The Eocene Baltic amber deposit represents the largest accumulation of fossil resin worldwide, and hundreds of thousands of entrapped arthropods have been recovered. Although Baltic amber preserves delicate plant structures in high fidelity, angiosperms of the "Baltic amber forest" remain poorly studied. We describe a pistillate partial inflorescence of Castanopsis (Fagaceae), expanding the knowledge of Fagaceae diversity from Baltic amber. The amber specimen was investigated using light microscopy and synchrotron-radiation-based X-ray micro-computed tomography (SRμCT). The partial inflorescence is a cymule, consisting of an involucre of scales that surround all four pistillate flowers, indicating a dichasium cupule. Subtending bracts are basally covered with peltate trichomes. Flowers possess an urecolate perianth of six nearly free lobes, 12 staminodia hidden by the perianth, and a tri-locular ovary that is convex-triangular in cross section. The exceptional three-dimensional preservation suggests that the fossil belongs to the extant East Asian genus Castanopsis. The amber inclusion represents the first record of Castanopsis from Baltic amber and the first pistillate inflorescence of Fagaceae from Eurasia. The partial female inflorescence reported here provides an important addition to acorns of Castanopsis described from middle Eocene strata of Europe. Furthermore, the intercontinental distribution of Castanopsis in the Eocene is confirmed. The amber fossil also broadens the picture of the Baltic amber source area, indicating oligotrophic, sandy, bog-like habitats. Finally, this study underscores the great benefit of SRμCT as a powerful tool to investigate plant inclusions from amber in a nondestructive way.

An Enigmatic Miniaturized and Attenuate Whole Lizard from the Mid-Cretaceous Amber of Myanmar

We report the discovery of a new genus and species of amber-preserved lizard from the mid-Cretaceous of Myanmar. The fossil is one of the smallest and most complete Cretaceous lizards ever found, preserving both the articulated skeleton and remains of the muscular system and other soft tissues. Despite its completeness, its state of preservation obscures important diagnostic features. We determined its taxonomic allocation using two approaches: we used previously identified autapomorphies of squamates that were observable in the fossil; and we included the fossil in a large squamate morphological data set. The apomorphy-based identification of this specimen, including comparative data on trunk elongation in squamates, suggests its allocation to the stem-group Anguimorpha. Results from the phylogenetic analysis places the fossil in one of four positions: as sister taxon of either Shinisaurus crocodilurus or Parasaniwa wyomingensis, at the root of Varanoidea, or in a polytomy with Varanoidea and a fossorial group retrieved in a previous assessment of squamate relationships. It is clear that this fossil has many similarities with anguimorph squamates and, if this taxonomic allocation is correct, this fossil would represent the first amber-preserved member of stem Anguimorpha ever recorded, and the smallest known member of that group. It further emphasizes the role of amber inclusions in expanding our understanding of the diversity of Cretaceous lizard communities.

Propiestus archaicus, the first Mesozoic amber inclusion of piestine rove beetles and its evolutionary and biogeographical significance (Coleoptera: Staphylinidae: Piestinae)

Fossil records of piestine rove beetles are very limited, with only two definite species from Mesozoic Chinese compressions, a single taxon from mid-Eocene Baltic amber and a doubtful Oligocene compression fossil from France. Here, a remarkable new genus and species, Propiestus archaicus gen. et sp. nov., is described based on a well-preserved individual in Upper Cretaceous Burmese amber from northern Myanmar (Cenomanian, c. 99 Ma). It represents the first piestine fossil found in Mesozoic amber. The fine morphological characters preserved as an amber inclusion enable a confident systematic placement within the subfamily based on both our detailed observations and phylogenetic analyses. The resulting trees revealed a strongly supported sister-group relationship with the extant genus Piestus, comprising all currently known piestine species from the Neotropical region and one from the Nearctic. Our new discovery is congruent with a hypothesis of the Gondwanan affinity of insects found from Burmese amber. Considering the geological data as well as several previous studies, the current distribution of Piestus could possibly be explained by either a relictual Gondwanan distribution or the widespread presence of the clade Propiestus + Piestus on Pangea, rather than subsequent dispersal events during the Cenozoic. Nonetheless, more evidence is needed to corroborate the true biogeographical origin and past distribution of this clade. In agreement with strong external similarities with living Piestinae, Propiestus probably exhibits a specialized body plan, including a flattened body, long, slender antennae and short legs, suggesting that it inhabited microhabitats under the bark of rotting wood as do its modern congeners.http://zoobank.org/urn:lsid:zoobank.org:pub:3411BDFD-54A1-4555-A870-813758BC61DA

Eocene isopods on electric rays: tracking ancient biological interactions from a complex fossil record

AbstractIsopod crustaceans have developed a variety of feeding strategies, which impact on their various life habits over time. Apart from morphological adaptations and the typical secondary deformations that some parasitic isopods inflict on their host's exoskeleton, traces of feeding behaviours involving isopods on their victim/food are seldom fossilized. Many of these rare occurrences consist of cases for which the degree of association between the isopods and their potential food source is unclear, or the interaction only very briefly explained (recently analysed cases excepted). There are two limiting problems in identifying the biological nature of fossilized associations: (1) direct associations of organisms preserved as ‘imprint’ (as opposed to inclusions in cherts or amber) are shaped by several taphonomic events difficult to identify (such as the time of death, burial and fossilization of the organism); (2) even in modern nature, differences within syn vivo interactions (like parasitism and micropredation) are poorly understood in marine systems. We report the occurrence of isopods associated with ancient chondrichthyans which also represent rare cases of the preservation of several fossil isopods on larger organisms. These organisms are adult electric rays of the genus †Titanonarke Carvalho from the late Ypresian (Eocene) of the Monte Postale site, Bolca Lagerstätte, Italy. By examining: (1) the involved lineages of rays and isopods; (2) the taphonomy of the association; (3) its environmental context; and (4) biological/adaptive features; we identify this association as a selective case, either of ancient scavenging or of micropredation on specific electric rays by isopods.

Biological Inclusions in Amber from the Paleogene Chickaloon Formation of Alaska

The Chickaloon Formation in south-central Alaska contains rich coal deposits dated very close to the Paleocene-Eocene boundary, immediately beneath which occur dispersed nodules of amber along with abundant remains of Metasequoia, dicots, and monocots. The nodules are small (less than 10 mm in length), nearly 10,000 of which were screened, yielding several inclusions of fungi and plant fragments, but mostly terrestrial arthropods: 29 specimens in 10 orders and 13 families. The fungi include resinicolous hyphae and a dark, multiseptate hyphomycete. Plants include wood/bark fragments and fibers, and the microphylls of a bryophyte (probably a moss, Musci). Among the arthropods are arachnids: mites (Acari: Oribatida), Pseudoscorpionida, and the bodies and a silken cocoon of spiders (Araneae). Insecta include Blattodea, Thysanoptera, Hemiptera (Heteroptera and Aphidoidea), Coleoptera (Dermestidae: Megatominae), Trichoptera, Diptera (Chironomidae: Tanypodinae), and Hymenoptera (Formicidae: Formicinae). Nymphal aphids predominate (65% of the arthropod individuals), which were probably feeding on the source tree, likely Metasequoia. There is a bias in preservation toward small arthropods (mean body length 0.75 mm) that are surface-dwelling (nonwinged) stages and taxa. Chickaloon amber contains the most northerly fossil records of pseudoscorpions, thrips, Dermestidae, and Cenozoic ants and mites, so the deposit is contributing unique data on high-latitude paleodiversity of the Paleogene hothouse earth.

First boganiine beetle in mid-Cretaceous amber from northern Myanmar (Coleoptera: Boganiidae)

Cretoboganium gei gen. et sp. nov., a new amber inclusion of the cucujoid family Boganiidae is described and figured based on a well-preserved adult from the mid-Cretaceous Burmese amber (Hukawng Valley, northern Myanmar), some 99 million years ago. Based on the presence of a pair of pronotal callosities, Cretoboganium can be firmly placed in the extant subfamily Boganiinae, a small group currently comprising two small austral genera. Our discovery represents the first fossil record for Boganiinae. It also demonstrates another example that an apparently austral group may have its sister group occurred in today’s northern hemisphere. Together with the other fossil boganiid known from the Middle Jurassic of China, the finding suggests that Boganiidae is an ancient and relict group. Moreover, the present biogeographic distribution of Boganiinae is indicative of an earlier origin of this subfamily, which likely originated before the breakup of the Gondwanan supercontinent.

Marine microorganisms as amber inclusions: insights from coastal forests of New Caledonia

Abstract. Marine microorganisms trapped in amber are extremely rare in the fossil record, and the few existing inclusions recovered so far originate from very few pieces of Cretaceous amber from France. Marine macroscopic inclusions are also very rare and were recently described from Cretaceous Burmese amber and Early Miocene Mexican amber. Whereas a coastal setting for the amber source forests is generally proposed, different scenarios have been suggested to explain how these marine inclusions can become trapped in a resin of terrestrial origin. These scenarios include an introduction of marine organisms (i) through high tides, (ii) from storms and resulting in flooding of the littoral/estuarine forest floor, (iii) in resin dropped into the sea in mangrove-type settings, or (iv) by wind and sea spray. We investigated the possibility of a wind-driven introduction of marine microorganisms into tree resins using modern coastal conifer forests with the highly resinous Cook pine (Araucaria columnaris) in New Caledonia as a model for the Cretaceous amber forests from France. By exposing fresh resin surfaces on the seaward side of the trees and the collection of older in situ resins, we confirmed that marine microorganisms can become trapped on sea-exposed resin, along with remnants from terrestrial organisms, and salt crystals. We suggest that, for cases where only a few marine inclusions are discovered in an amber deposit, an origin from aeolian background deposition is feasible. However, a more energetic but possibly still aeolian event is likely needed to explain the high numbers of marine microorganisms embedded in pieces of Cretaceous amber from France.

Diverse Cretaceous larvae reveal the evolutionary and behavioural history of antlions and lacewings

Myrmeleontiformia are an ancient group of lacewing insects characterized by predatory larvae with unusual morphologies and behaviours. Mostly soil dwellers with a soft cuticle, their larvae fossilize only as amber inclusions, and thus their fossil record is remarkably sparse. Here, we document a disparate assemblage of myrmeleontiform larvae from the mid-Cretaceous amber (99 Ma) of Myanmar, evidence of a considerable diversification. Our cladistic analysis integrating extant and extinct taxa resolves the fossils as both stem- and crown-groups. Similarities between extinct and extant species permit inferences of larval ethology of the fossil species through statistical correlation analyses with high support, implying that morphological disparity matched behavioural diversity. An improved understanding of the evolutionary history of antlions and relatives supports the conclusion that hunting strategies, such as camouflage and fossoriality, were acquired early within the lineage.