Compression Fossils Research Articles

A Fossil Thrips (Thysanoptera: Terebrantia) from a Cretaceous Deposit in Orapa1

Abstract A fossil thrips is described using a single compression fossil from an Upper Cretaceous deposit, the Orapa Diamond Mine in Botswana. It is the first record of a Cretaceous thrips from Africa. It is diagnosed by the following characteristics: general habitus; narrow, straplike forewing and hindwing with fringe cilia; with forewing becoming progressively larger in distal third; and abdomen with dense transversal rows of microtrichia and terminal setae. The specimen is complete, except that the antennae are absent. At Orapa, the fossil thrips would have been possibly found feeding on leaves, stem or flower tissues of both gymnosperms and angiosperms in and around the crater lake. The fossil thrips adds to the taxonomic diversity of the Orapa fauna. Moreover, it broadens the knowledge of the diversity, geography and evolution of Mesozoic Thysanoptera.

Morphological and palaeoecological aspects of fossil insects unveiled by UV-A light

Studying insect fossils, particularly those preserved as compressions in sedimentary matrices, can be difficult due to the taphonomic processes that often result to poor preservation and contrast of structures compared to the embedding matrix. To address this, we propose a user-friendly and simple methodology based on UV-light to study insect fossils and select specimens of interest for more advanced imagery exploration. While UV-light imaging has been previously applied to compressions of arthropod fossils, it typically involved laser light sources. Our approach allows the investigation of fossils using an affordable, compact, and portable UV-light source, along with a simple and replicable low-cost protocol.•The methodology is based on UV-light induced natural fluorescence of sediment and fossil remains.•UV-light is effective on compression fossils to gain natural contrast and enhance observation of body structures like veins or setae on wings.•UV-light is effective to reveal palaeoecological information such as pollen grains preserved on specimens, especially near or on putative pollinator or pollen-eating taxa.

A new fossil species of Meliolinites Selkirk associated with Rhodoleia leaves from the Upper Pliocene of southwestern China

ABSTRACT Fossil epifoliar fungi are valuable indicators of paleoenvironment and paleoecology. The Meliolaceae, members of which typically inhabit the surface of living plants as biotrophs or pathogens, is one of the largest groups of epifoliar fungi. In this study, we report a novel fossil species of Meliolinites Selkirk (fossil Meliolaceae), Meliolinites tengchongensis, on the lower epidermis of compressed fossil Rhodoleia (Hamamelidaceae) leaves from the Upper Pliocene Mangbang Formation of Tengchong, Yunnan, southwestern China. Meliolinites tengchongensis is characterized by web-like, superficial, brown to dark brown, septate, and branching mycelia bearing 2-celled appressoria and unicellular phialides. The fungal colonies also include ellipsoidal, 5-celled, 4-septate ascospores and dark brown perithecia with suborbicular outline and verrucose surface. The well-preserved vegetative and reproductive organs help us to explore the potential disease process of the new fossil species. Besides, the presence of fungal remains indicates that the fungal taxon might have maintained its host preference since at least the Late Pliocene. Furthermore, the occurrence of both fossil fungi and their host plants in Tengchong indicate a subtropical–tropical, warm, and humid climate during the Late Pliocene, whereas the distribution pattern of the fungi on the host leaves suggests that Rhodoleia may have been a part of the middle–upper canopies in the Tengchong Late Pliocene multilayered forest.

A Fossil Paederinae from a Lacustrine Deposit at Orapa Diamond Mine in Botswana1

Abstract A staphylinid beetle morphotype, Mesostaphylinus orapa sp. n., is described based on a single well–preserved compression fossil from an Upper Cretaceous lacustrine deposit at Orapa Diamond Mine in Botswana. Mesostaphylinus Zhang is placed in the extant subfamily Paederinae based on general habitus and an unambiguous synapomorphy, the concealed antennal insertions. Mesostaphylinus is a genus of convenience for fossils belonging in Paederinae, but lacking diagnostic features (e.g., maxillary palpomeres) to assign and delineate them into appropriate tribes and subtribes. The fossil described here is morphologically similar to M. laiyangensis Zhang, M. fraternus Zhang, Wang and Xu, M. elongatus Solodovnikov and Yue, M. yixianus Solodovnikov and Yue, and M. antiquus Solodovnikov and Yue. Compared to other fossil staphylinid beetles that have been described thus far, the fossil also portrays morphological conservatism, morphological stasis, or arrested evolution dating back to the Cretaceous, thereby suggesting a punctuated equilibrium pattern of evolution.

Expanding the Mesozoic Record of Early Brachyceran Fly Larvae, including New Larval Forms with Chimera-Type Morphologies.

Diptera are one of the four megadiverse groups of holometabolan insects. Flies perform numerous ecological functions, especially in their larval stages. We can assume that this was already the case in the past; however, fly larvae remain rare in most deposits. Here we report new dipteran larvae preserved in Cretaceous (about 99 Ma) Kachin amber from Myanmar and, even older, Jurassic (about 165 Ma) compression fossils from China. Through light microscopy and micro-CT scanning we explore their peculiar morphology and discuss their possible phylogenetic affinities. Several larvae seem to represent the lineage of Stratiomyomorpha. A few others present characters unique to Xylophagidae (awl-flies), as well as to Athericidae (water sniper-flies), resulting in a chimeric morphology. Understanding the exact relationships of most of these specimens with a particular lineage remains challenging, since they differ considerably from any other known dipteran larvae and present some unique traits. Additionally, we report new specimens of Qiyia jurassica Chen et al., 2014, supposedly parasitic larvae, most likely representatives of Athericidae. These new findings offer valuable insights into the evolution of the early diversification of the brachyceran flies and underscore the importance of immature stages in understanding the evolutionary history and ecology of flies.

New fossil caddisflies (Trichoptera, Dysoneuridae) from the Lower Cretaceous of Inner Mongolia, China

A new caddisfly species, Khasurtia apertalocularis sp. nov., and a Dysoneuridae gen. indet. sp., are described and illustrated, and Utania defecta Sukatsheva, 1982 is redescribed, based on 13 fossil specimens from the Lower Cretaceous Yixian Formation of Inner Mongolia, China. This is the first report of the family Dysoneuridae in China, enhancing the geographical distribution of this family and providing reference to the paleogeography. New specimens show that the species previously classified as Dysoneuridae from the compression fossils and Myanmar amber belong to different families based on the characters of wing, ocelli and antennae; and support that the caddisflies in Myanmar amber be elevated to two families, Burmapsychidae and Cretapsychidae.

Two new species of Ghilarellinae (Hymenoptera, Cephoidea, Sepulcidae) from the Lower Cretaceous

One new species, Ghilarella elegantula sp. nov., in the family Sepulcidae is described and illustrated based on a well-preserved compression fossil specimen from the Lower Cretaceous Yixian Formation of northeastern China. The new species is characterized by having a large body size; forewing with costal area obviously narrowed basally, Sc and 2r-m absent, 1-Rs short, cell 1mcu large; and ovipositor elongated. In addition, Ghilarella cf. mercurialis is given its own name Ghilarella kopylovi as the new species in Ghilarella. An updated key for the known species of Ghilarella is provided. Moreover, a well-preserved ovipositor is reported for the first time in the subfamily Ghilarellinae. The two new species not only improve our understanding of Ghilarella by adding more morphological features, but also expand the distribution ranges of Ghilarellinae fossil records.

Depositional history of Devonian to lower Carboniferous (Tournaisian) strata, northern Wyoming and southern Montana, USA

The lower Frasnian (Upper Devonian) Maywood Formation records incision of valleys into lower Paleozoic bedrock in fluvial to estuarine settings in northern Wyoming and deposition in estuarine to marine environments in southern Montana (USA). A distinctive fossil assemblage of microconchids, plant compression fossils, fish fossils, and microspores represent fauna and flora that lived in, and adjacent to, salinity-stressed ecological niches in the upper reaches of the Maywood valleys. A similar fossil assemblage is recorded in older Devonian valley-fill deposits of the Lower Devonian Beartooth Butte Formation, indicating that valley incision and subsequent transgression, occurred repeatedly over a span of nearly 30 million years with organisms tracking the marine incursions into the valleys. The fossil charcoal in the Maywood Formation captures a record of fire in adjacent terrestrial ecosystems. The amount of dioxygen (O2) was thus above the fire window level (16% by volume) and might have been near modern levels in the earliest Late Devonian atmosphere. The nearshore deposits of the Maywood Formation are overlain by extensive shallow carbonate shelf strata of the Jefferson Formation, likely resulting from a global transgression in the earliest Frasnian. A paired positive and negative δ13Ccarbonate [carb] isotopic excursion in the Jefferson with a range of >6‰ is a signal of the globally recognized “punctata” Event. The unconformably overlying Madison Limestone is lower Carboniferous, except for a thin basal Upper Devonian unit with marine palynomorphs. The Madison regionally records eastward transgression and establishment of widespread marine deposition. It also contains two positive δ13Ccarb excursions (up to ∼7.5‰) that make up the mid-Tournaisian (= Kinderhookian−Osagean boundary) carbon isotope excursion (TICE/KOBE). These isotope data provide a framework for regional and global correlation of northern Rocky Mountain strata and an archive of environmental and evolutionary change during the middle−late Paleozoic transition.

Paleozoic cave system preserves oldest-known evidence of amniote skin.

The richest and most diverse assemblage of early terrestrial tetrapods is preserved within the infilled cave system of Richards Spur, Oklahoma (289-286 Mya1). Some of the oldest-known terrestrial amniotes2,3 are exquisitely preserved here because of early impregnation and encasement of organic material by oil-seep hydrocarbons within rapidly deposited clay-rich cave sediments under toxic anoxic conditions.4 This phenomenon has also afforded the preservation of exceedingly rare integumentary soft tissues, reported here, providing critical first evidence into the anatomical changes marking the transition from the aquatic and semiaquatic lifestyles of anamniotes to the fully terrestrial lifestyles of early amniotes. This is the first record of a skin-cast fossil (3D carbonization of the skin proper) from the Paleozoic Era and the earliest known occurrence of epidermal integumentary structures. We also report on several compression fossils (carbonized skin impressions), all demonstrating similar external morphologies to extant crocodiles. A variety of previously unknown ossifications, as well as what are likely palpebral ossifications of the deeper dermis layer of the skin, are also documented. These fossils also serve as invaluable references for paleontological reconstructions. Chromatographic analysis of extractable hydrocarbons from bone and cave samples indicates that the source rock is the Devonian age Woodford Shale. Hydrocarbons derived from ancient marine organisms interacting with geologically younger terrestrial vertebrates have therefore resulted in the oldest-known preservation of amniote skin proper.

Flatbed scanners as versatile tools for studying surface details of compression fossils

Flatbed scanners as versatile tools for studying surface details of compression fossils

A new species of Protopsyllidiidae (Hemiptera, Sternorrhyncha) from the Middle Jurassic of northeastern China.

Based on two compression fossils from the Middle Jurassic Jiulongshan Formation of Daohugou Village, Ningcheng County, Inner Mongolia, China, a new fossil species, Poljanka curticapillata L, Luo & Yao, sp. nov., of the extinct family Protopsyllidiidae is described. It is characterized by the flagellomeres 16 slender and 6 small subsections at apex, the presence of genae, the basal tarsomere almost equal to the apical tarsomere of fore and middle legs, and basal tarsomere about 2.11 times as long as apical tarsomere of hind leg, and the forewing veins R longer than M + Cu1, Cu1 with curved Cu1a and Cu1b, and Cu1a/Cu1b ratio 3.463.63. These body features and combination of forewing venation characteristics differ the new taxon from all other known species of Poljanka Klimaszewski, 1995. We also provide a key to the species of Poljanka and revise the diagnosis of the genus.

Impact of increasing morphological information by micro-CT scanning on the phylogenetic placement of Darwin wasps (Hymenoptera, Ichneumonidae) in amber

The correct interpretation of fossils and their reliable taxonomic placements are fundamental for understanding the evolutionary history of biodiversity. Amber inclusions often preserve more morphological information than compression fossils, but are often partially hidden or distorted, which can impede taxonomic identification. Here, we studied four new fossil species of Darwin wasps from Baltic and Dominican amber, using micro computed tomography (micro-CT) scans and 3D reconstructions to accurately interpret and increase the availability of morphological information. We then infer their taxonomic placement in a Bayesian phylogenetic analysis by combining morphological and molecular data of extant and fossil Darwin wasps and evaluate the impact and usefulness of the additional information from micro-CT scanning. The results show that although we gained significant morphological information from micro-CT scanning, especially concerning measurements and hidden dorsal and ventral structures, this did not impact subfamily-level placement for any of the four fossils. However, micro-CT scanning improved the precision of fossil placements at the genus level, which might be key in future dating and diversification analyses. Finally, we describe the four new fossil species as Rhyssa gulliveri sp. nov. in Rhyssinae, Triclistus levii sp. nov. in Metopiinae, Firkantus freddykruegeri gen. et. sp. nov. in Pimplinae and Magnocula sarcophaga gen. et sp. nov. in Phygadeuontinae. The first two species are the first known representatives of the subfamilies Rhyssinae and Metopiinae in amber.

Characterization of a pyritized fossil pollen cone from Clarkia, Idaho

The Miocene Lake deposit in Clarkia, Idaho is composed of highly fossiliferous silty clays. These rocks were formed in an anoxic and likely toxic deep lacustrine environment which facilitated the fossilization of plant material with a high amount of morphological detail. Many of the plant compression fossils exhibit exceptional preservation, including the preservation of original biomolecules. Pyritized plant specimens are much less common and the details of plant pyritization at this site are not yet fully understood. Pyritized male pollen cones from Taxodium dubium provide an opportunity to explore the processes of pyrite preservation in the Clarkia deposit.One specimen was examined using scanning electron microscopy (SEM) and energy-dispersive x-ray analysis (EDS). The only pyrite textures observed on this specimen were framboids and framboidal microcrystals. Pyrite was found in abundance on the surface of the pollen cones and to a much lesser extent on the surface of the stem. Underneath the pyrite coating, both the cones and stem were carbon-rich, indicating organic preservation. Some pyrite crystals were found in the interior of the stem, but likely originated from the exterior and developed through cracks or tears in the fossil. Pyrite crystals did not form inside the cell walls of the stem. The decaying specimen likely provided a scaffold that could facilitate the formation of pyrite upon the specimen surface. Gypsum crystals found in close association with pyrite likely formed as a product of oxidation after the specimens were taken from the rock.

A new compression fossil, Eotriadomeroides abjunctus Huber, gen. & sp. nov. (Hymenoptera, Mymaridae), in Eocene shale from the Kishenehn Formation, USA

A new fossil genus and species of fairyfly, Eotriadomeroides abjunctus Huber & Greenwalt, gen. and sp. nov. (Hymenoptera: Chalcidoidea: Mymaridae), is described and illustrated from a female preserved as a compression fossil in middle Eocene shale from the Kishenehn Formation, Montana, USA. It is compared to extant species of Neotriadomerus Huber, known only from Australia, and Triadomerus Yoshimoto, a Cretaceous amber fossil from Canada. It is suggested that these three genera, classified together in Triadomerini, likely the most ancestral lineage of Mymaridae, are evidence of the Middle or perhaps Late Jurassic origin of the family.

Description of a new fossil genus of conifer sawfly (Hymenoptera: Diprionidae) revealed by UV light

Oligomonoctenus neytiriae gen. et sp. nov., the second fossil representative of the family Diprionidae from the uppermost Oligocene of Aix-en-Provence, France, is described on the basis of a well-preserved compression fossil. It is compared to the other extant and fossil diprionid genera. Its morphology and wing venation support placement in the subfamily Monocteninae. Paleomonoctenus patriciae, the other diprionid described from the same paleolake, also belongs to the Monocteninae. On the other hand, the Eocene-Lower Oligocene genus Eodiprion would be attributable to the Diprioninae but needs revision. This discovery suggests that the two diprionid subfamilies were already present and diversified during the Eocene-Oligocene.

Macroscopic carbonaceous compression fossils from the Tonian Liulaobei Formation in the Huainan region of North China

Macroscopic carbonaceous compression fossils are key to understand the early evolution of eukaryotes, explore the development of multicellularity, and strengthen the basis of biostratigraphic correlation during the Tonian Period (ca. 1000–720 Ma). Despite the potential geobiological importance of early macrofossils, the fossil record of Tonian macro-organisms is rarely documented. Here we describe an assemblage of diversified carbonaceous macrofossils from the Tonian Liulaobei Formation in the Huainan region, North China. In this study, we examine a large population of these macrofossils, clarify their taxonomy, and tentatively interpret their phylogenetic affinities. This assemblage consists of thirteen distinct morphotaxa, including eight genera and three new species, showing remarkable taxonomic diversity and domination of coenocytic macroalgae. The new data improve our knowledge about early Neoproterozoic biodiversity, and indicate a Tonian increase in morphological and taxonomic diversity of macrofossils compared to the Mesoproterozoic Era. This study also suggests that macroalgae may have begun to diversify and played a crucial ecological role in Tonian marine ecosystems.

Sediment-encased pressure–temperature maturation experiments elucidate the impact of diagenesis on melanin-based fossil color and its paleobiological implications

AbstractMelanin pigments are central to colors and patterns in modern vertebrate integuments, which inform upon ecological and behavioral strategies like crypsis, aposematism, and sociosexual selection. Over the last decade, melanin has emerged as a valuable tool for predicting color in exceptionally preserved fossil feathers and subsequent testing of paleobiological hypotheses in long-extinct dinosaurs and birds. Yet much remains to be learned about melanin stability, diagenetic alterations to melanin chemistry, and their implications for “paleocolor reconstruction.” Pressure–temperature maturation experiments with modern feathers offer a way to examine these topics but have mostly been conducted in closed-system capsules or open-system aluminum foil. Both methods have operational limitations and do not consider the filtering effect of porous sediment matrices on thermally labile chemical groups versus stable ones during natural fossilization. We use sediment-encased maturation to resolve this issue and demonstrate replication of organic preservation of melanin highly comparable to compression fossils. Our experiments, coupled with time-of-flight secondary ion mass spectrometry, show predictable volatilization of N/S-bearing molecules and increased melanin cross-linking with elevated temperatures. We also suggest that eumelanin is more stable compared with pheomelanin at higher temperatures, explaining why eumelanic colors (black, dark brown, iridescent) are better preserved in fossils than pheomelanic ones (reddish brown). Furthermore, we propose that proteins preferentially undergo hydrolysis more so than forming N-heterocycles in selectively open systems analogous to natural matrices. Thus, we conclude that melanin pigments and not diagenetically altered protein remnants are the key players in promoting fossilization of soft tissues like feathers.

The earliest pollen-loaded insects from the Lower Permian of Russia.

Recent fossil discoveries suggest that the coevolution of insect pollinators and gymnosperms started long before the appearance of flowering plants. One of the keys to understanding the origins of pollination relationships is fossil insects with gymnosperm pollen attached to the body surface. Such fossils are exceedingly rare to find, especially from the Palaeozoic, a time when ambers with insect inclusions were absent. Here, we report compression fossils of Early Permian tillyardembiid insects (Polyneoptera) preserved with pollen on their heads, thoraces, legs and abdomens. This is the earliest finding of pollen-bearing insects, predating the previous oldest record from the Middle Jurassic by ca 120 Ma. Judging by the pollen composition, tillyardembiids visited a narrow range of host plants, including Rufloriaceae (Cordaitales). While it is impossible to say for certain whether tillyardembiids as pollen consumers contributed to pollination, a trophic specialization of this kind could be considered an evolutionary precursor of pollination mutualism.

Phosphatized microfossils from the Miaohe Member of South China and their implications for the terminal Ediacaran biodiversity decline

The upper Ediacaran Miaohe Member (∼550 Ma) in South China is well known for exceptionally preserved macroscopic carbonaceous compression fossils (i.e., the Miaohe biota) that are pivotal in understanding the marine ecology and environment during the terminal Ediacaran Period. However, micro-organisms, which are also important biotic components of marine ecosystems, are poorly documented and largely limited to simple leiospheres and filaments in the Miaohe Member and equivalent strata in South China and around the world. Here we report a moderately diverse assemblage of cellularly preserved microfossils from phosphorites and siliceous phosphorite nodules and bands of the Miaohe Member at the Maxi section, Hubei Province, South China. Ten named species of eight genera, four open nomenclatures, and two unnamed taxa have been identified, including several multicellular algal fossils and various coccoidal and filamentous cyanobacteria. Abundant spheroidal fossils are morphologically analogous to Megasphaera, which has previously been interpreted as a putative metazoan embryo. Together with previously described microfossils from equivalent strata of Miaohe Member, these microfossils expand our understanding of the evolution of marine ecosystems prior to the Cambrian explosion. The late Ediacaran Maxi assemblage and the early Ediacaran Weng’an biota, both preserved through phosphatization, share several taxa. Notably, Doushantuo-Pertatataka-type acanthomorphs (DPAs) are absent from the Maxi assemblage but abundant in the Weng’an biota, consistent with a late Ediacaran decline of DPAs, which may have ushered in the terminal Ediacaran decline of soft-bodied macro-organisms of the Ediacara biota during the Kotlin crisis or in the last 10 million years of the Ediacaran Period.

A large enigmatic fossil from the early Cambrian (Series 2, Stage 3) Heatherdale Shale of South Australia

ABSTRACT A large enigmatic fossil is described from the early Cambrian (Series 2, Stage 3) Heatherdale Shale in the Fleurieu Peninsula, South Australia. It has an almost circular outline about 150 mm across, with an outer rim and 27–30 evenly-spaced rays that extend about two-thirds of the distance to the centre of the structure; it shows radial symmetry. There is a featureless central area with a width about one-third that of the entire specimen. The fossil is preserved as pale-coloured material that stands out slightly above the surrounding mudstone. XRF data indicate that there is little compositional difference between the fossil and the enclosing rock. The fossil may appear to be a transverse section of a larger organism, but it does not continue down into the surrounding rock. This suggests it is a non-mineralised compression fossil that retains the remnants of a three-dimensional structure. Possible affinities with radiodont oral cones, ctenophores, eldonioids, scyphozoa and archaeocyaths are discussed, but no definite assignment can be made.