A rhabdocoel turbellarian (Platyhelminthes, Typhloplanoida) in Baltic amber with a review of fossil and sub-fossil platyhelminths

Abstract. Palaeosoma balticus n. g., n. sp. (Rhabdocoela, Typhloplanoida), the oldest body fossil of a turbellarian and the first representative of the phylum Platyhelminthes found in fossilized resin, is described from Baltic amber 40 million years old. Characters of the fossil turbellarian are epidermal cilia, rhabdoids, a rosulate pharynx, adhesive papillae, and sensory bristles. The body cavity contains developing eggs or capsules. The fossil demonstrates that rhabdocoels had developed a terrestrial habit and were producing subitaneous eggs by the Eocene. A summary of the fossil and sub-fossil records of platyhelminths is presented.     

Oceanic transport of calcified eggs: taphonomic and biogeographic implications

Estimates of the temporal and spatial resolution of fossil egg assemblages are required to constrain the inferences that can logically be drawn during assemblage analysis. Consequently, understanding egg transport mechanisms is required before conclusions are developed. Bird eggs are buoyant during part of development and can float from near shore nests during high tides, storm surges, or flooding. Complete and unbroken eggs have survived transoceanic transport. Evidence of these transport processes operating in the past is suggested by the recovery of fossil eggshell in marine deposits. Transport of eggs can potentially confound fossil assemblage spatial analysis since evidence of oceanic transport may not be present on an eggshell when collected. Bird embryos exposed to cold temperatures and immersed in both fresh and salt water can survive from hours to two days, suggesting that oceanic transport of viable eggs is possible, a conclusion further supported by field observations. Eggs of other taxa show similar environmental survival trends and may also be capable of surviving oceanic transport through floatation or rafting. In addition, if viable eggs are transported across seas and hatch, emigration or gene flow of terrestrial egg-laying vertebrates may be possible between landmasses.     

First fossil record of stalked spermatophores with sperm (Collembola: Hexapoda)

Spermatozoa and stalked spermatophores in Baltic amber represent the first report of these reproductive structures in the fossil record. A comparison of this material with sperm and simple stalked spermatophores from extant invertebrates indicates that the fossil structures originated from a springtail (Collembola: Hexapoda). This conclusion is supported by the presence of a female springtail, Sminthurus longicornis Kock and Berendt (Sminthuridae: Symphypleona), in the same piece of amber. This specimen, which appears to have been molting at the time of death, is adjacent to objects interpreted as springtail eggs. The present find establishes the existence of the indirect method of sperm transfer by the late Eocene (40 Ma).     

First report of fossil turtle eggshell west of the Colorado Plateau

The first fossil turtle eggshell from North America west of the Colorado Plateau (UCMP 218504) is described, adding to the growing global record of chelonian eggshell. Ten blocks of mudstone were collected from the Upper Miocene (Clarendonian) Orinda Formation, Contra Costa County, California, during the excavation of the Caldecott Tunnel Fourth Bore. They contain rigid eggshell averaging 500 μm in thickness. Closely packed shell units with a height/width ratio of 2:1 are composed of radiating, acicular crystals originating from a basal core, a set of characters that support the identification of the eggshell as chelonian, and further as testudinoid. Egg diameter is estimated at between 34.2 and 42.4 mm based on shell curvature. Adult carapace length is estimated to be 70.7 cm, a size similar to fossils of Hesperotestudo known from California and present in the Orinda Formation. UCMP 218504 greatly extends the geographic record of turtle fossil eggshell and adds to the limited number of mid-Neogene eggs. It also provides evidence for a warm climate in Miocene California and demonstrates the south-eastern contraction of conditions appropriate for tortoise reproduction during the last 10 million years.     

Structure of fossil dinosaur eggshell from the Aix Basin,France

At least four types of dinosaur eggshell are distinguished among samples of fossil eggshell from Late Cretaceous deposits of southern France. Recognition is based on shell microstructure, porosity, and shell thickness. Estimated values of water vapour conductance for these dinosaur eggshells are much greather than predicted for avian eggs, suggesting that the eggs were incubated under conditions of high humidity, such as would occur underground.     

A new peculiar dinosaur egg,Sankofa pyrenaica oogen. nov. oosp. nov. from the Upper Cretaceous coastal deposits of the Aren Formation,south‐central Pyrenees,Lleida, Catalonia,Spain

Abstract: A new type of small, ovoid dinosaur egg, Sankofa pyrenaica oogen. nov. oosp. nov., with a prismatic type eggshell is described from upper Cretaceous (upper Campanian–Maastrichtian) deposits of the Montsec area, South Pyrenean Central Unit, Lleida, Catalonia, Spain. This egg type was sub‐vertically laid in only two rich monospecific sites of a single stratigraphic layer from coastal deposits of the Aren Formation, interpreted as an emerged beach ridge of a barrier island – lagoon depositional system. The size and shape of these eggs with their asymmetric poles are roughly similar to modern hen eggs, which is unusual in the Cretaceous fossil egg record. Its phylogenetic position clusters with bird and Troodontid eggs. A morphospace analysis of egg shapes shows the similarity of the new egg to a Campanian fossil bird egg from Argentina, both being intermediate between modern‐bird eggs and extinct nonavian theropod eggs. However, the eggshell microstructure of Sankofa pyrenaica differs from that of bird eggs in its incipient squamatic texture. It has a peculiar pattern of interlocking small crystals in the middle of the palisade layer, instead of the thick squamatic structure commonly present in modern avian eggshells. This new egg type is attributed to a small theropod, probably with a single oviduct like birds and whose mosaic distribution of features is a combination between that of birds and nonavian theropods. This enhances the arguments supporting the close phylogenetic relationships between both groups.     

New tribe,genus, and species of paedogenetic gall midges (Diptera,Lestremiidae: Krassiloviolini trib. nov.) from the Late Cretaceous Taimyr amber

Paedogenetic fossil midges of the family Lestremiidae are revealed for the first time. Only eight species of eight gall midge genera belonging to five tribes of the subfamily Micromyinae (Lestremiidae) and two species of two genera of Porricondylinae (Cecidomyiidae: Porricondylinae sp., Holoneurini sp.) have previously been described from the Santonian Taimyr amber of Yantardakh. The new tribe Krassiloviolini trib. nov. differs from other tribes of Lestremiidae in the strong reduction of veins and flagellomeres, slightly differing in length first and second tarsomeres of the middle and hind tarsi, 3-segmented apical plates of the ovipositor, and the presence of paedogenesis. A new genus and species, Krassiloviola geniusloci gen. et sp. nov., is described based on a female that is characterized by the first front tarsomere 1.3 times as long as the second, short 2+7-segmented antennae, presence of stem and large narrow sensoria on flagellomeres, wide wings with strongly reduced vein R5, slightly forked Cu, and absence of fragment C behind the fusion with R5. The presence of two very large specific eggs is evidence of the existence of paedogenesis in the Late Cretaceous. Previously, fossil paedogenetic eggs have only been known in Miastor vlaskini (Fedotova et Perkovsky) described from the Late Eocene Rovno amber.     

Crocodylomorph eggs and eggshells from the Adamantina Formation (Bauru Group), Upper Cretaceous of Brazil

Abstract: Compared with crocodylomorph body fossils, the record of fossil crocodiloid eggs is scarce and poorly understood, a gap partially attributed to their typically thin eggshell, which is not conducive to preservation. A remarkable new association of well‐preserved eggs and eggshells from the Adamantina Formation (Bauru Group, Upper Cretaceous) is described and compared to other known materials, while the significance of their unique oological features is discussed. These eggs constitute a new ootaxon, Bauruoolithus fragilis oogen. et oosp. nov., diagnosed by the following characteristics: elongate and elliptical egg with blunt ends; length‐to‐diameter ratio of 1:0.55; outer surface slightly undulating; shell thickness ranging from 0.15 to 0.25 mm; pore openings elliptical or teardrop‐shaped, ranging from 30 to 80 μm in diameter; and shell units wider than higher, with the interstices forming an obtuse triangle. Specimens of Bauruoolithus also show only slight signs of extrinsic degradation that, coupled with the evidence that some of them constitute hatched eggs, suggests that the egg‐laying taxon had a different pattern of egg incubation, in which the hatchling could break through the rather thin eggshell relatively easily and that the extrinsic degradation of the eggshell was not necessary. This contrasts with the pattern of incubation for all other known crocodylomorphs and crocodiloid eggs, where extrinsic degradation is a key component of the hatching process.     

First fossil gravid turtle provides insight into the evolution of reproductive traits in turtles

Here we report on the first discovery of shelled eggs inside the body cavity of a fossil turtle and on an isolated egg clutch, both referable to the Cretaceous turtle Adocus. These discoveries provide a unique opportunity to gain insight into the reproductive traits of an extinct turtle and to understand the evolution of such traits among living turtles. The gravid adult and egg clutch indicate that Adocus laid large clutches of rigid-shelled spherical eggs and established their nests near rivers, traits that are shared by its closest living relatives, the soft-shelled turtles. Adocus eggshell, however, was probably more rigid than that of living turtles, based on its great thickness and structure, features that may represent unique adaptations to intense predation or to arid nest environments. In light of the reproductive traits observed in Adocus, the distribution of reproductive traits among turtles reveals that large clutches of rigid-shelled eggs are primitive for hidden-necked turtles (cryptodirans) and that spherical eggs may have evolved independently within this group.     

Reidentification of Avian Embryonic Remains from the Cretaceous of Mongolia

Embryonic remains within a small (4.75 by 2.23 cm) egg from the Late Cretaceous, Mongolia are here re-described. High-resolution X-ray computed tomography (HRCT) was used to digitally prepare and describe the enclosed embryonic bones. The egg, IGM (Mongolian Institute for Geology, Ulaanbaatar) 100/2010, with a three-part shell microstructure, was originally assigned to Neoceratopsia implying extensive homoplasy among eggshell characters across Dinosauria. Re-examination finds the forelimb significantly longer than the hindlimbs, proportions suggesting an avian identification. Additional, postcranial apomorphies (strut-like coracoid, cranially located humeral condyles, olecranon fossa, slender radius relative to the ulna, trochanteric crest on the femur, and ulna longer than the humerus) identify the embryo as avian. Presence of a dorsal coracoid fossa and a craniocaudally compressed distal humerus with a strongly angled distal margin support a diagnosis of IGM 100/2010 as an enantiornithine. Re-identification eliminates the implied homoplasy of this tri-laminate eggshell structure, and instead associates enantiornithine birds with eggshell microstructure composed of a mammillary, squamatic, and external zones. Posture of the embryo follows that of other theropods with fore- and hindlimbs folded parallel to the vertebral column and the elbow pointing caudally just dorsal to the knees. The size of the egg and embryo of IGM 100/2010 is similar to the two other Mongolian enantiornithine eggs. Well-ossified skeletons, as in this specimen, characterize all known enantiornithine embryos suggesting precocial hatchlings, comparing closely to late stage embryos of modern precocial birds that are both flight- and run-capable upon hatching. Extensive ossification in enantiornithine embryos may contribute to their relatively abundant representation in the fossil record. Neoceratopsian eggs remain unrecognized in the fossil record.     

Fossil avian eggshell preserves ancient DNA

Owing to exceptional biomolecule preservation, fossil avian eggshell has been used extensively in geochronology and palaeodietary studies. Here, we show, to our knowledge, for the first time that fossil eggshell is a previously unrecognized source of ancient DNA (aDNA). We describe the successful isolation and amplification of DNA from fossil eggshell up to 19 ka old. aDNA was successfully characterized from eggshell obtained from New Zealand (extinct moa and ducks), Madagascar (extinct elephant birds) and Australia (emu and owl). Our data demonstrate excellent preservation of the nucleic acids, evidenced by retrieval of both mitochondrial and nuclear DNA from many of the samples. Using confocal microscopy and quantitative PCR, this study critically evaluates approaches to maximize DNA recovery from powdered eggshell. Our quantitative PCR experiments also demonstrate that moa eggshell has approximately 125 times lower bacterial load than bone, making it a highly suitable substrate for high-throughput sequencing approaches. Importantly, the preservation of DNA in Pleistocene eggshell from Australia and Holocene deposits from Madagascar indicates that eggshell is an excellent substrate for the long-term preservation of DNA in warmer climates. The successful recovery of DNA from this substrate has implications in a number of scientific disciplines; most notably archaeology and palaeontology, where genotypes and/or DNA-based species identifications can add significantly to our understanding of diets, environments, past biodiversity and evolutionary processes.     

Differential label‐free quantitative proteomic analysis of avian eggshell matrix and uterine fluid proteins associated with eggshell mechanical property

Eggshell strength is a crucial economic trait for table egg production. During the process of eggshell formation, uncalcified eggs are bathed in uterine fluid that plays regulatory roles in eggshell calcification. In this study, a label‐free MS‐based protein quantification technology was used to detect differences in protein abundance between eggshell matrix from strong and weak eggs (shell matrix protein from strong eggshells and shell matrix protein from weak eggshells) and between the corresponding uterine fluids bathing strong and weak eggs (uterine fluid bathing strong eggs and uterine fluid bathing weak eggs) in a chicken population. Here, we reported the first global proteomic analysis of uterine fluid. A total of 577 and 466 proteins were identified in uterine fluid and eggshell matrix, respectively. Of 447 identified proteins in uterine fluid bathing strong eggs, up to 357 (80%) proteins were in common with proteins in uterine fluid bathing weak eggs. Similarly, up to 83% (328/396) of the proteins in shell matrix protein from strong eggshells were in common with the proteins in shell matrix protein from weak eggshells. The large amount of common proteins indicated that the difference in protein abundance should play essential roles in influencing eggshell strength. Ultimately, 15 proteins mainly relating to eggshell matrix specific proteins, calcium binding and transportation, protein folding and sorting, bone development or diseases, and thyroid hormone activity were considered to have closer association with the formation of strong eggshell.     

When phylogeny meets geology and chemistry: doubts on the dating of Ethiopian amber

The first fossil species of a Melissotarsus ant is described (Melissotarsus ethiopiensis n. sp.), suggesting that Ethiopian amber could be cenozoic rather than cretaceous. This hypothesis is supported by a Fourier transform infrared spectroscopy (FTIR) analysis of the amber itself, suggesting a weak maturation of the fossil resin, and a revision of the pyrolysis–gas chromatography–mass spectrometry (PY-GC-MS) analysis done by Schmidt and his collaborators in 2010, in an article in which the deposit was described for the first time.     

Changes in eggshell permeability to oxygen during the early developmental stages in diapause eggs of Bombyx mori

An apparatus for direct measurement of the eggshell permeability to oxygen was devised to test the hypothesis that diapause initiation in the Bombyx mori egg is caused by the eggshell becoming insufficiently perrneable to air to allow further embryogenesis. Using this apparatus, it was found that permeability of the eggshell to oxygen decreased dramatically during the first 2 days of incubation in prospective diapause eggs, but no appreciable changes were found in nondiapause eggs for the first 6 days of incubation. The rates of oxygen uptake by diapause and nondiapause eggs increased in a similar pattern for 26 h after oviposition. Thereafter, the rate of oxygen uptake in the former decreased while that of latter continuously increased. The cause and physiological meaning of the rapid drop of eggshell permeability just before diapause initiation are obscure. It is suggested that the decrease in oxygen uptake may be due to decreased eggshell permeability to oxygen.     

Two new theropod egg sites from the Late Jurassic Lourinhã Formation,Portugal

Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal da Rola and Porto das Barcas, both near Lourinhã, central-west Portugal. Casal da Rola yields eggshells with an obliquiprismatic morphotype comparable to those from a nest with the associated fossil embryos from Paimogo, tentatively assigned to the theropod Lourinhanosaurus antunesi. The Porto das Barcas eggshells have a dendrospherulitic morphotype with a prolatocanaliculate pore system. This morphotype was also recognised in eggshells from a clutch with associated Torvosaurus embryos at the Porto das Barcas locality. A preliminary cladistic analysis of eggshell morphology suggests theropod affinities for the Casal da Rola eggs, but is unable to resolve the phylogenetic position of the Porto das Barcas eggs. The eggshells at both sites are preserved in distal flood plain mudstones and siltstones. Carbonate concretions within the deposits indicate paleosol development.     

福建漳浦中中新世几种藓类植物研究*

亚洲新生代藓类植物化石非常稀少,漳浦琥珀是目前已知的我国低纬度地区唯一含苔藓植物化石的新生代琥珀矿床。漳浦琥珀源自中中新世气候适宜期(~14-17 Ma)的龙脑香树脂,温暖潮湿的热带季雨林气候和广泛分布的龙脑香科植物,为藓类植物的生长、多样性演化和三维立体保存提供了条件。本研究共报道了漳浦县中中新世藓类植物化石3个属种,包括:白发藓属Leucobryum Hampe、牛舌藓属Anomodon Hook.et Taylor和扁枝藓属Homalia(Brid.)B.S.G.。首次利用三维X射线断层扫描技术(Micro-CT)研究了白发藓属化石,发现其与现生种短枝白发藓Leucobryum humillimum Cardot非常相似,因此将其命名为短枝白发藓(相似种)Leucobryum cf.humillimum。此外,当前牛舌藓属Anomodon和扁枝藓属Homalia化石是东亚地区的首例记录。漳浦琥珀中的藓类植物化石揭示了中中新世时期苔藓植物的多样性,丰富了东亚低纬度地区新生代苔藓植物的化石记录。     

内蒙古巴音满都呼晚白垩世棱齿龙蛋化石的发现

本文记述的恐龙蛋化石标本,采自内蒙古乌拉特后旗巴音满都呼上白垩统牙道黑达组中。蛋化石在蛋窝中排列的方式和蛋壳的显微结构特征与北美发现的含有可鉴定为棱齿龙胚胎骨骼的蛋化石基本相似,但还有一些差别,如蛋壳外表面不具纵向细纹,柱状层中鱼骨型纹饰不明显等。因此,应为棱齿龙科中另一新的属种代表。     

Ancient Ephemeroptera–Collembola Symbiosis Fossilized in Amber Predicts Contemporary Phoretic Associations

X-ray computed tomography is used to identify a unique example of fossilized phoresy in 16 million-year-old Miocene Dominican amber involving a springtail being transported by a mayfly. It represents the first evidence (fossil or extant) of phoresy in adult Ephemeroptera and only the second record in Collembola (the first is also preserved in amber). This is the first record of Collembola using winged insects for dispersal. This fossil predicts the occurrence of similar behaviour in living springtails and helps explain the global distribution of Collembola today.