Publications by authors named "Lida Xing"

37 Publications

Evidence for a mixed-age group in a pterosaur footprint assemblage from the early Upper Cretaceous of Korea.

Sci Rep 2022 Jun 23;12(1):10707. Epub 2022 Jun 23.

School of the Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China.

Here we describe a new pterosaur footprint assemblage from the Hwasun Seoyuri tracksite in the Upper Cretaceous Jangdong Formation of the Neungju Basin in Korea. The assemblage consists of many randomly oriented prints in remarkably high densities but represents a single ichnotaxon, Pteraichnus. Individuals exhibit a large but continuous size range, some of which, with a wingspan estimated at 0.5 m, are among the smallest pterosaurs yet reported from the Upper Cretaceous, adding to other recent finds which contradict the idea that large and giant forms entirely dominated this interval. Unusual features of the tracks, including relatively long, slender pedal digit impressions, do not match the pes of any known Cretaceous pterosaur, suggesting that the trackmakers are as yet unknown from the body fossil record. The Hwasun pterosaur footprints appear to record gregarious behavior at the exact location by individuals of different ages, hinting at the possibility that pterosaurs gathered in mixed-age groups.
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http://dx.doi.org/10.1038/s41598-022-14966-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9226182PMC
June 2022

Hadrosauroid eggs and embryos from the Upper Cretaceous (Maastrichtian) of Jiangxi Province, China.

BMC Ecol Evol 2022 05 9;22(1):60. Epub 2022 May 9.

Beaty Centre for Species Discovery and Palaeobiology Section, Canadian Museum of Nature, Ottawa, ON, K1P 6P4, Canada.

Background: Dinosaur eggs containing embryos are rare, limiting our understanding of dinosaur development. Recently, a clutch of subspherical dinosaur eggs was discovered while blasting for a construction project in the Upper Cretaceous red beds (Hekou Formation) of the Ganzhou Basin, Jiangxi Province, China. At least two of the eggs contain identifiable hadrosauroid embryos, described here for the first time.

Results: The eggs, attributable to Spheroolithidae indet., are thin-walled and small (~ 660 mL) compared to those of Lambeosaurinae. The shape of the embryonic squamosal is reminiscent of that seen in the Late Cretaceous hadrosauroids Levnesovia transoxiana, Tanius sinensis, and Nanningosaurus dashiensis, suggestive of possible affinities.

Conclusion: The small size of the eggs and embryos, similar to those of Hadrosaurinae, indicates that the larger eggs and hatchlings typical of Lambeosaurinae are evolutionarily derived.
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http://dx.doi.org/10.1186/s12862-022-02012-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9088101PMC
May 2022

Facile synthesis of nanocellulose-based CuO/Ag heterostructure as a surface-enhanced Raman scattering substrate for trace dye detection.

Int J Biol Macromol 2022 Apr 19;205:366-375. Epub 2022 Feb 19.

College of Materials and Energy, South China Agricultural University, Guangzhou 510642, PR China. Electronic address:

Semiconductor metal-oxide/metal heterostructures with synergetic properties have potential applications in photocatalysis and optical sensors. Here, CuO sub-micro cubes were synthesized under environmentally benign conditions using 2, 2, 6, 6-tetramethylpyperdine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils as a reducing and stabilizing agent. Then the surface of the CuO cubes was decorated with silver nanoparticles (AgNPs) by a substitution reaction. The CuO/Ag heterostructures within the cellulose nanofibrils (CNFs) network were employed as a promising surface-enhanced Raman scattering (SERS) assay for efficient sensing of methylene blue (MB), reaching a maximum enhancement factor (EF) of 4.0 × 10. Their SERS intensities depended on the coverage density of AgNPs and the wavelength of the excitation laser. The excellent SERS performance may result from the charge transfer between Ag and CuO molecules and the strong electromagnetic field at the interface. The CNF-CuO/Ag substrates were capable of detecting MB dye down to 10 M level with a relative standard deviation of 10-15%, demonstrating great sensitivity and reproducibility.
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http://dx.doi.org/10.1016/j.ijbiomac.2022.02.102DOI Listing
April 2022

An exquisitely preserved theropod dinosaur embryo sheds light on avian-like prehatching postures.

iScience 2022 Jan 21;25(1):103516. Epub 2021 Dec 21.

School of GeoSciences, University of Edinburgh, Edinburgh, UK.

Despite the discovery of many dinosaur eggs and nests over the past 100 years, articulated embryos are remarkably rare. Here we report an exceptionally preserved, articulated oviraptorid embryo inside an elongatoolithid egg, from the Late Cretaceous Hekou Formation of southern China. The head lies ventral to the body, with the feet on either side, and the back curled along the blunt pole of the egg, in a posture previously unrecognized in a non-avian dinosaur, but reminiscent of a late-stage modern bird embryo. Comparison to other late-stage oviraptorid embryos suggests that prehatch oviraptorids developed avian-like postures late in incubation, which in modern birds are related to coordinated embryonic movements associated with tucking - a behavior controlled by the central nervous system, critical for hatching success. We propose that such pre-hatching behavior, previously considered unique to birds, may have originated among non-avian theropods, which can be further investigated with additional discoveries of embryo fossils.
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http://dx.doi.org/10.1016/j.isci.2021.103516DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8786642PMC
January 2022

Crab in amber reveals an early colonization of nonmarine environments during the Cretaceous.

Sci Adv 2021 Oct 20;7(43):eabj5689. Epub 2021 Oct 20.

Royal Saskatchewan Museum, Regina, SK S4P 4W7, Canada.

Amber fossils provide snapshots of the anatomy, biology, and ecology of extinct organisms that are otherwise inaccessible. The best-known fossils in amber are terrestrial arthropods—principally insects—whereas aquatic organisms are rarely represented. Here, we present the first record of true crabs (Brachyura) in amber—from the Cretaceous of Myanmar [~100 to 99 million years (Ma)]. The new fossil preserves large compound eyes, delicate mouthparts, and even gills. This modern-looking crab is nested within crown Eubrachyura, or “higher” true crabs, which includes the majority of brachyuran species living today. The fossil appears to have been trapped in a brackish or freshwater setting near a coastal to fluvio-estuarine environment, bridging the gap between the predicted molecular divergence of nonmarine crabs (~130 Ma) and their younger fossil record (latest Cretaceous and Paleogene, ~75 to 50 Ma) while providing a reliable calibration point for molecular divergence time estimates for higher crown eubrachyurans.
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http://dx.doi.org/10.1126/sciadv.abj5689DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8528423PMC
October 2021

Lower cretaceous avian-dominated, theropod, thyreophoran, pterosaur and turtle track assemblages from the Tugulu Group, Xinjiang, China: ichnotaxonomy and palaeoecology.

PeerJ 2021 28;9:e11476. Epub 2021 May 28.

School of the Earth Sciences and Resources, China University of Geoscience (Beijing), Beijing, China.

Rich tetrapod ichnofaunas, known for more than a decade, from the Huangyangquan Reservoir (Wuerhe District, Karamay City, Xinjiang) have been an abundant source of some of the largest Lower Cretaceous track collections from China. They originate from inland lacustrine clastic exposures of the 581-877 m thick Tugulu Group, variously divided into four formations and subgroups in the northwestern margin of the Junggar Basin. The large Huangyangquan track assemblages occur in the Lower layer/Subgroup II. Similarly-composed track assemblages also occur at the smaller Asphaltite site in the Upper Layer/Subgroup III. The Huangyangquan assemblages have yielded more than 1,500 identified tracks including abundant tracks of avian and non-avian theropods, pterosaurs and turtles and less abundant tracks of stegosaurs. Previous avian track identifications have been reassessed to conclude that is a taphotaxon and might be better accommodated in the ichnogenus which appears to be the dominant avian ichnotaxon. The avian track is also recognized and represents the first occurrence of this ichnogenus in China. Although the Huangyangquan assemblages lack some of the larger components (e.g., sauropodan and ornithopodan tracks) known from other Lower Cretaceous localities, the association of abundant tracks of smaller tetrapods (avian and non-avian theropods, pterosaurs and turtles) appears to be representative of lacustrine basin faunas of this region, and are an excellent example of the shorebird ichnocoenosis/ichnofacies concept. This is the first comprehensive review and re-analysis of an important Lower Cretaceous ecosystem.
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http://dx.doi.org/10.7717/peerj.11476DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8166242PMC
May 2021

Biodegradable cellulose I (II) nanofibrils/poly(vinyl alcohol) composite films with high mechanical properties, improved thermal stability and excellent transparency.

Int J Biol Macromol 2020 Dec 5;164:1766-1775. Epub 2020 Aug 5.

College of Materials and Energy, South China Agricultural University, Guangzhou 510642, PR China. Electronic address:

Cellulose nanofibrils (CNFs) with cellulose I and II allomorphs were efficiently prepared by sulfuric acid hydrolysis of eucalyptus cellulose under three different conditions followed by mechanical treatments: (i) classical sulfuric acid hydrolysis of cellulose I (CNF-I), (ii) sulfuric acid hydrolysis of mercerized cellulose II (MNF-II), and (iii) solubilization and hydrolysis of cellulose I by concentrated sulfuric acid and subsequent recrystallization in water (RNF-II). Crystal structure, surface chemistry, morphology and thermal properties of three CNFs were investigated and compared. Three CNFs of 2-10 wt% were mixed with PVA to prepare biodegradable composite films. CNF allomorph had significant impact on crystal structure, mechanical and thermal properties of the PVA composites. The maximum Young's modulus of CNF-I/PVA, RNF-II/PVA and MNF-II/PVA were increased by 62, 32 and 44%, respectively. Addition of CNFs raised onset degradation temperature (T) and thermal decomposition temperature (T) of PVA nanocomposite, while decreased the melting temperature (T). Temperature window (T - T) for the melt processing of nanocomposites (10 wt% CNF loading) were increased 2.8, 3.2 and 2.5 times for CNF-I/PVA, RNF-II/PVA and MNF-II/PVA, respectively. All composite films remained excellent transparency with addition of CNFs. This comparative study provided important knowledge of selecting CNF allomorph for fabrication of high-performance CNF/PVA composites.
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http://dx.doi.org/10.1016/j.ijbiomac.2020.07.320DOI Listing
December 2020

Retraction Note: Hummingbird-sized dinosaur from the Cretaceous period of Myanmar.

Nature 2020 08;584(7822):652

Beijing Advanced Sciences and Innovation Center, Chinese Academy of Sciences, Beijing, China.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41586-020-2553-9DOI Listing
August 2020

Hummingbird-sized dinosaur from the Cretaceous period of Myanmar.

Nature 2020 03 11;579(7798):245-249. Epub 2020 Mar 11.

Beijing Advanced Sciences and Innovation Center, Chinese Academy of Sciences, Beijing, China.

Skeletal inclusions in approximately 99-million-year-old amber from northern Myanmar provide unprecedented insights into the soft tissue and skeletal anatomy of minute fauna, which are not typically preserved in other depositional environments. Among a diversity of vertebrates, seven specimens that preserve the skeletal remains of enantiornithine birds have previously been described, all of which (including at least one seemingly mature specimen) are smaller than specimens recovered from lithic materials. Here we describe an exceptionally well-preserved and diminutive bird-like skull that documents a new species, which we name Oculudentavis khaungraae gen. et sp. nov. The find appears to represent the smallest known dinosaur of the Mesozoic era, rivalling the bee hummingbird (Mellisuga helenae)-the smallest living bird-in size. The O. khaungraae specimen preserves features that hint at miniaturization constraints, including a unique pattern of cranial fusion and an autapomorphic ocular morphology that resembles the eyes of lizards. The conically arranged scleral ossicles define a small pupil, indicative of diurnal activity. Miniaturization most commonly arises in isolated environments, and the diminutive size of Oculudentavis is therefore consistent with previous suggestions that this amber formed on an island within the Trans-Tethyan arc. The size and morphology of this species suggest a previously unknown bauplan, and a previously undetected ecology. This discovery highlights the potential of amber deposits to reveal the lowest limits of vertebrate body size.
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http://dx.doi.org/10.1038/s41586-020-2068-4DOI Listing
March 2020

Transition of cellulose supramolecular structure during concentrated acid treatment and its implication for cellulose nanocrystal yield.

Carbohydr Polym 2020 Feb 1;229:115539. Epub 2019 Nov 1.

College of Materials and Energy, South China Agricultural University, Guangzhou, 510642, PR China. Electronic address:

Cellulose nanocrystals with cellulose I and II allomorphs (CNC-I and CNC-II) were prepared from eucalyptus cellulose I substrate by controlling the sulfuric acid hydrolysis conditions, including acid concentration (56-64 wt%), reaction temperature (45 or 60 °C) and time (10-120 min). The crystalline structures were verified by XRD and C-NMR. CNC-II only appeared at very restricted reaction conditions. The rapid cellulose supramolecular structure transition under sulfuric acid concentration of around 60 wt% resulted in an abrupt change in CNC yield. A maximal CNC yield of 66.7% was obtained at acid concentration of 58 wt% and reaction temperature of 60 °C. CNC-I exhibited spindle-shape, while CNC-II showed a twisted strip structure. The state of order in cellulose during the acid hydrolysis process has been studied using a coagulation method. A tentative model of CNC-I and CNC-II formation was then proposed. This work provided significant knowledge for the production of CNCs with high yield and controllable allomorph.
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http://dx.doi.org/10.1016/j.carbpol.2019.115539DOI Listing
February 2020

A mid-Cretaceous enantiornithine foot and tail feather preserved in Burmese amber.

Sci Rep 2019 10 29;9(1):15513. Epub 2019 Oct 29.

Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, Yunnan, 650091, China.

Since the first skeletal remains of avians preserved in amber were described in 2016, new avian remains trapped in Cretaceous-age Burmese amber continue to be uncovered, revealing a diversity of skeletal and feather morphologies observed nowhere else in the Mesozoic fossil record. Here we describe a foot with digital proportions unlike any previously described enantiornithine or Mesozoic bird. No bones are preserved in the new specimen but the outline of the foot is recorded in a detailed skin surface, which is surrounded by feather inclusions including a partial rachis-dominated feather. Pedal proportions and plumage support identification as an enantiornithine, but unlike previous discoveries the toes are stout with transversely elongated digital pads, and the outer toe appears strongly thickened relative to the inner two digits. The new specimen increases the known diversity and morphological disparity among the Enantiornithes, hinting at a wider range of habitats and behaviours. It also suggests that the Burmese amber avifauna was distinct from other Mesozoic assemblages, with amber entrapment including representatives from unusual small forms.
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http://dx.doi.org/10.1038/s41598-019-51929-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6820775PMC
October 2019

Land Snail with Periostracal Hairs Preserved in Burmese Amber.

iScience 2019 Oct 12;20:567-574. Epub 2019 Oct 12.

Naturhistorisches Museum der Burgergemeinde Bern, 3005 Bern, Switzerland; Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland; Senckenberg Forschungsinstitut und Naturmuseum, 60325 Frankfurt am Main, Germany.

Excellently preserved fossils often provide important insights into evolutionary histories and adaptations to environmental change in Earth's biogeologic record. Mid-Cretaceous Burmese amber, for example, is a proven reservoir for spectacular findings. Here we document the first record of a fossil land snail with periostracal hairs preserved in amber. We interpret the development of hairs as an adaptation to the tropical forest environment, serving as a mechanism to increase adhesion of the snail to plants during foraging while collecting and transporting seeds in the process. The present record coincides with a major global radiation of angiosperms, a main food resource for terrestrial snails. As such, the expansion of flowering plants likely triggered this evolutionary adaptation and, thus, the diversification of land snails in the Cretaceous.
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http://dx.doi.org/10.1016/j.isci.2019.09.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6834951PMC
October 2019

A New Enantiornithine Bird with Unusual Pedal Proportions Found in Amber.

Curr Biol 2019 07 11;29(14):2396-2401.e2. Epub 2019 Jul 11.

Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.

Recent discoveries of vertebrate remains trapped in middle Cretaceous amber from northern Myanmar [1, 2] have provided insights into the morphology of soft-tissue structures in extinct animals [3-7], in particular, into the evolution and paleobiology of early birds [4, 8, 9]. So far, five bird specimens have been described from Burmese amber: two isolated wings, an isolated foot with wing fragment, and two partial skeletons [4, 8-10]. Most of these specimens contain the remains of juvenile enantiornithine birds [4]. Here, we describe a new specimen of enantiornithine bird in amber, collected at the Angbamo locality in the Hukawng Valley. The new specimen includes a partial right hindlimb and remiges from an adult or subadult bird. Its foot, of which the third digit is much longer than the second and fourth digits, is distinct from those of all other currently recognized Mesozoic and extant birds. Based on the autapomorphic foot morphology, we erect a new taxon, Elektorornis chenguangi gen. et sp. nov. We suggest that the elongated third digit was employed in a unique foraging strategy, highlighting the bizarre morphospace in which early birds operated.
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http://dx.doi.org/10.1016/j.cub.2019.05.077DOI Listing
July 2019

Author Correction: Exquisitely-preserved, high-definition skin traces in diminutive theropod tracks from the Cretaceous of Korea.

Sci Rep 2019 May 30;9(1):8289. Epub 2019 May 30.

School of the earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
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http://dx.doi.org/10.1038/s41598-019-43832-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6541587PMC
May 2019

Inter-amphibian predation in the Early Cretaceous of China.

Sci Rep 2019 05 23;9(1):7751. Epub 2019 May 23.

Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, England.

For most fossil taxa, dietary inference relies primarily on indirect evidence from jaw morphology and the dentition. In rare cases, however, preserved gut contents provide direct evidence of feeding strategy and species interaction. This is important in the reconstruction of food webs and energy flow through ancient ecosystems. The Early Cretaceous Chinese Jehol Biota has yielded several such examples, with lizards, birds, small dinosaurs, and mammals as both predator and prey. Here we describe an Early Cretaceous fossil frog specimen, genus Genibatrachus, that contains an adult salamander within its body cavity. The salamander is attributed to the hynobiid-like genus Nuominerpeton. The salamander skeleton is complete and articulated, suggesting it was caught and swallowed shortly before the frog itself died and was buried.
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http://dx.doi.org/10.1038/s41598-019-44247-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6533365PMC
May 2019

Exquisitely-preserved, high-definition skin traces in diminutive theropod tracks from the Cretaceous of Korea.

Sci Rep 2019 02 14;9(1):2039. Epub 2019 Feb 14.

School of the Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China.

Small theropod tracks, ichnogenus Minisauripus, from the Jinju Formation (Cretaceous) of Korea reveal exquisitely preserved skin texture impressions. This is the first report for any dinosaur of skin traces that cover entire footprints, and every footprint in a trackway. Special sedimentological conditions allowed footprint registration without smearing of skin texture patterns which consist of densely-packed, reticulate arrays of small (<0.5 mm) polygons, preserved as both impressions and casts, the latter essentially foot replicas. The skin texture resembles that reported for two Lower Cretaceous avian theropods (birds) from China which had quite different foot morphologies. This is also the oldest report of Minisauripus from Korea predating five reports from the Haman Formation of inferred Albian age. Minisauripus is now known from six Korean and three Chinese localities, all from the Lower Cretaceous. This gives a total sample of ~95 tracks representing ~54 trackways. With >80% of tracks <3.0 cm long, Minisauripus is pivotal in debates over whether small tracks represent small species, as the database suggests, or juveniles of large species.
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http://dx.doi.org/10.1038/s41598-019-38633-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6375998PMC
February 2019

A fully feathered enantiornithine foot and wing fragment preserved in mid-Cretaceous Burmese amber.

Sci Rep 2019 01 30;9(1):927. Epub 2019 Jan 30.

Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, 90007, USA.

Over the last three years, Burmese amber (~99 Ma, from Myanmar) has provided a series of immature enantiornithine skeletal remains preserved in varying developmental stages and degrees of completeness. These specimens have improved our knowledge based on compression fossils in Cretaceous sedimentary rocks, adding details of three-dimensional structure and soft tissues that are rarely preserved elsewhere. Here we describe a remarkably well-preserved foot, accompanied by part of the wing plumage. These body parts were likely dismembered, entering the resin due to predatory or scavenging behaviour by a larger animal. The new specimen preserves contour feathers on the pedal phalanges together with enigmatic scutellae scale filament (SSF) feathers on the foot, providing direct analogies to the plumage patterns observed in modern birds, and those cultivated through developmental manipulation studies. Ultimately, this connection may allow researchers to observe how filamentous dinosaur 'protofeathers' developed-testing theories using evolutionary holdovers in modern birds.
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http://dx.doi.org/10.1038/s41598-018-37427-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6353931PMC
January 2019

Smallest known raptor tracks suggest microraptorine activity in lakeshore setting.

Sci Rep 2018 11 15;8(1):16908. Epub 2018 Nov 15.

Graduate School of Culture Technology, Korea Advanced Institute of Science and Technology, 291, Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea.

Ongoing studies of a multiple track-bearing horizons from massive excavations in the Jinju Formation (Lower Cretaceous) of South Korea have yielded a remarkable diversity of avian, non-avian dinosaur, pterosaur, crocodilian and mammal tracks, many very small and well preserved. Here we report diminutive, didactyl tracks (~1.0 cm long) assigned to a new dromaeosaurid ichnogenus Dromaeosauriformipes, which resembles the larger, but still quite small, ichnogenus Dromaeosauripus, also from the same formation only 30 km away. These diminutive tracks are consistent with the foot size of smaller dromaeosaurid taxa like Early Cretaceous Microraptor from China, and may represent diminutive species or juveniles of larger species. The association of tracks with lakeshore sediments is consistent with the evidence that Microraptor was a fish eater. Two trackways and isolated tracks indicate variable trackmaker gaits and speeds. If oviparous, as assumed for most non-avian dinosaur neonates, the trackmakers must have hatched from tiny eggs. Previous studies of the Korean Cretaceous indicate the presence of other diminutive (~1.0 cm long) theropod tracks (Minisauripus). Such occurrences strongly suggest that small tracks attributed to juveniles, or very small tetrapod species, are more common than previously supposed especially where suitable preservation conditions prevailed.
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http://dx.doi.org/10.1038/s41598-018-35289-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6237872PMC
November 2018

A mid-Cretaceous embryonic-to-neonate snake in amber from Myanmar.

Sci Adv 2018 07 18;4(7):eaat5042. Epub 2018 Jul 18.

Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.

We present the first known fossilized snake embryo/neonate preserved in early Late Cretaceous (Early Cenomanian) amber from Myanmar, which at the time, was an island arc including terranes from Austral Gondwana. This unique and very tiny snake fossil is an articulated postcranial skeleton, which includes posterior precloacal, cloacal, and caudal vertebrae, and details of squamation and body shape; a second specimen preserves a fragment of shed skin interpreted as a snake. Important details of skeletal ontogeny, including the stage at which snake zygosphene-zygantral joints began to form along with the neural arch lamina, are preserved. The vertebrae show similarities to those of fossil Gondwanan snakes, suggesting a dispersal route of Gondwanan faunas to Laurasia. Finally, the new species is the first Mesozoic snake to be found in a forested environment, indicating greater ecological diversity among early snakes than previously thought.
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http://dx.doi.org/10.1126/sciadv.aat5042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6051735PMC
July 2018

The earliest direct evidence of frogs in wet tropical forests from Cretaceous Burmese amber.

Sci Rep 2018 06 14;8(1):8770. Epub 2018 Jun 14.

Florida Museum of Natural History, University of Florida, Gainesville, 32611, Florida, USA.

Frogs are a familiar and diverse component of tropical forests around the world. Yet there is little direct evidence from the fossil record for the antiquity of this association. We describe four fossil frog specimens from mid-Cretaceous (~99 mya) amber deposits from Kachin State, Myanmar for which the associated fauna provides rich paleoenvironmental context. Microcomputed tomographic analysis provides detailed three-dimensional anatomy for these small frogs, which is generally unavailable for articulated anurans in the Mesozoic. These crown-group anuran specimens provide the earliest direct evidence for anurans in a wet tropical forest. Based on a distinct combination of skeletal characters, at least one specimen has clear similarities to living alytoid frogs as well as several Mesozoic taxa known from the Jehol Biota in China. Whereas many Mesozoic frogs are from seasonal and mesic paleoenvironments, these fossils provide the earliest direct evidence of anurans in wet tropical forests.
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http://dx.doi.org/10.1038/s41598-018-26848-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6002357PMC
June 2018

Cellulose I and II nanocrystals produced by sulfuric acid hydrolysis of Tetra pak cellulose I.

Carbohydr Polym 2018 Jul 18;192:184-192. Epub 2018 Mar 18.

College of Materials and Energy, South China Agricultural University, Guangzhou, 510642, PR China. Electronic address:

Polymorphism is an important factor associated with the cellulose nanomaterial properties. In this study, cellulose fibers (CFs) were efficiently isolated from waste Tetra pak packages, and cellulose I and II nanocrystals were produced by treatment of CFs with 64% sulfuric acid and controlling the reaction time from 15 to 30 min. Cellulose I (CI) was partially converted to cellulose II (CII) within 15 min and the resulting cellulose nanocrystal product (i.e. CNC15) contained 93.2% CII. Further extending the hydrolysis time decreased the CII content of CNC20 to 25.5% and CNC30 was completely CI without CII. CNC15 (285.1 ± 120.7 nm long, 50.6 ± 16.5 nm wide, 0.64 at% sulfur) was much thicker, slightly longer, less thermal stable and contained more sulfate groups than CNC30 (207.2 ± 77.8 nm long, 23.2 ± 7.8 nm wide, 0.34 at% sulfur). CNCs with controllable allomorph may have potentially diverse applications.
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http://dx.doi.org/10.1016/j.carbpol.2018.03.042DOI Listing
July 2018

Possible bite-induced abscess and osteomyelitis in Lufengosaurus (Dinosauria: sauropodomorph) from the Lower Jurassic of the Yimen Basin, China.

Sci Rep 2018 03 22;8(1):5045. Epub 2018 Mar 22.

State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, China.

We report an osseous abnormality on a specimen of the sauropod dinosaur Lufengosaurus huenei from the Fengjiahe Formation in Yuxi Basin, China. A gross pathological defect occurs on the right third rib, which was subjected to micro-computed tomographic imaging as an aid in diagnosis. The analysis of pathological characteristics and the shape of the abnormality is incompatible with impact or healed trauma, such as a common rib fracture, and instead suggests focal penetration of the rib, possibly due to a failed predator attack. The identification of characteristics based on gross morphology and internal micro-morphology presented by the specimen, suggests an abscess with osteomyelitis as the most parsimonious explanation. Osteomyelitis is a severe infection originating in the bone marrow, usually resulting from the introduction of pyogenic (pus-producing) bacteria into the bone. Micro-tomographic imaging of the lesion suggests a degree of healing and bone remodelling following post-traumatic wound infection with evidence of sclerotic bone formation at the site of pathological focus, indicating that L. huenei survived the initial trauma. However, as osteomyelitis can express through widespread systemic effects, including a lowering of immune response and overall condition, this disease may have been a contributing factor to the eventual death of the individual.
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http://dx.doi.org/10.1038/s41598-018-23451-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5864883PMC
March 2018

A gigantic marine ostracod (Crustacea: Myodocopa) trapped in mid-Cretaceous Burmese amber.

Sci Rep 2018 01 22;8(1):1365. Epub 2018 Jan 22.

State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, 100083, China.

The mid-Cretaceous Burmese amber (~99 Ma, Myanmar), widely known for exquisite preservation of theropods, also yields microfossils, which can provide important contextual information on paleoenvironment and amber formation. We report the first Cretaceous ostracod in amber-the gigantic (12.9 mm) right valve of an exclusively marine group (Myodocopa: Myodocopida) preserved in Burmese amber. Ostracods are usually small (0.5-2 mm), with well-calcified carapaces that provide an excellent fossil record extending to at least the Ordovician (~485 million years ago), but they are rarely encountered in amber. The new specimen effectively doubles the age of the ostracod amber record, offering the first representative of the Myodocopa, a weakly calcified group with a poor fossil record. Its carapace morphology is atypical and likely plesiomorphic. The preserved valve appears to be either a moulted exuvium or a dead and disarticulated specimen, and subsequent resin flows contain forest floor inclusions with terrestrial arthropods, i.e., fragmentary remains of spiders, and insect frass. These features resolve an enigmatic taphonomic pathway, and support a marginal marine setting for resin production.
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http://dx.doi.org/10.1038/s41598-018-19877-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5778021PMC
January 2018

Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features.

Nat Commun 2017 05 2;8:14972. Epub 2017 May 2.

College of Life Sciences, Peking University, Beijing 100871, China.

Asymmetrical feathers have been associated with flight capability but are also found in species that do not fly, and their appearance was a major event in feather evolution. Among non-avialan theropods, they are only known in microraptorine dromaeosaurids. Here we report a new troodontid, Jianianhualong tengi gen. et sp. nov., from the Lower Cretaceous Jehol Group of China, that has anatomical features that are transitional between long-armed basal troodontids and derived short-armed ones, shedding new light on troodontid character evolution. It indicates that troodontid feathering is similar to Archaeopteryx in having large arm and leg feathers as well as frond-like tail feathering, confirming that these feathering characteristics were widely present among basal paravians. Most significantly, the taxon has the earliest known asymmetrical troodontid feathers, suggesting that feather asymmetry was ancestral to Paraves. This taxon also displays a mosaic distribution of characters like Sinusonasus, another troodontid with transitional anatomical features.
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http://dx.doi.org/10.1038/ncomms14972DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5418581PMC
May 2017

Response to: Phylogenetic placement, developmental trajectories and evolutionary implications of a feathered dinosaur tail in Mid-Cretaceous amber.

Curr Biol 2017 03;27(6):R216-R217

Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada.

In his correspondence, Markus Lambertz [1] raises some concerns about the phylogenetic placement and feather development of DIP-V-15103, the amber-entombed tail section that we recently reported [2] as fragmentary remains of a non-pygostylian coelurosaur (likely within the basal part of Coelurosauria). We here would like to respond to these concerns.
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http://dx.doi.org/10.1016/j.cub.2017.02.023DOI Listing
March 2017

A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber.

Curr Biol 2016 12 8;26(24):3352-3360. Epub 2016 Dec 8.

Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.

In the two decades since the discovery of feathered dinosaurs [1-3], the range of plumage known from non-avialan theropods has expanded significantly, confirming several features predicted by developmentally informed models of feather evolution [4-10]. However, three-dimensional feather morphology and evolutionary patterns remain difficult to interpret, due to compression in sedimentary rocks [9, 11]. Recent discoveries in Cretaceous amber from Canada, France, Japan, Lebanon, Myanmar, and the United States [12-18] reveal much finer levels of structural detail, but taxonomic placement is uncertain because plumage is rarely associated with identifiable skeletal material [14]. Here we describe the feathered tail of a non-avialan theropod preserved in mid-Cretaceous (∼99 Ma) amber from Kachin State, Myanmar [17], with plumage structure that directly informs the evolutionary developmental pathway of feathers. This specimen provides an opportunity to document pristine feathers in direct association with a putative juvenile coelurosaur, preserving fine morphological details, including the spatial arrangement of follicles and feathers on the body, and micrometer-scale features of the plumage. Many feathers exhibit a short, slender rachis with alternating barbs and a uniform series of contiguous barbules, supporting the developmental hypothesis that barbs already possessed barbules when they fused to form the rachis [19]. Beneath the feathers, carbonized soft tissues offer a glimpse of preservational potential and history for the inclusion; abundant Fe suggests that vestiges of primary hemoglobin and ferritin remain trapped within the tail. The new finding highlights the unique preservation potential of amber for understanding the morphology and evolution of coelurosaurian integumentary structures.
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http://dx.doi.org/10.1016/j.cub.2016.10.008DOI Listing
December 2016

Mummified precocial bird wings in mid-Cretaceous Burmese amber.

Nat Commun 2016 06 28;7:12089. Epub 2016 Jun 28.

Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.

Our knowledge of Cretaceous plumage is limited by the fossil record itself: compression fossils surrounding skeletons lack the finest morphological details and seldom preserve visible traces of colour, while discoveries in amber have been disassociated from their source animals. Here we report the osteology, plumage and pterylosis of two exceptionally preserved theropod wings from Burmese amber, with vestiges of soft tissues. The extremely small size and osteological development of the wings, combined with their digit proportions, strongly suggests that the remains represent precocial hatchlings of enantiornithine birds. These specimens demonstrate that the plumage types associated with modern birds were present within single individuals of Enantiornithes by the Cenomanian (99 million years ago), providing insights into plumage arrangement and microstructure alongside immature skeletal remains. This finding brings new detail to our understanding of infrequently preserved juveniles, including the first concrete examples of follicles, feather tracts and apteria in Cretaceous avialans.
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http://dx.doi.org/10.1038/ncomms12089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4931330PMC
June 2016

Digit-only sauropod pes trackways from China--evidence of swimming or a preservational phenomenon?

Sci Rep 2016 Feb 18;6:21138. Epub 2016 Feb 18.

No. 208 Hydrogeological and Engineering Geological Team, Chongqing Bureau of Geological and Mineral Resource Exploration and Development, Chongqing 400700, China.

For more than 70 years unusual sauropod trackways have played a pivotal role in debates about the swimming ability of sauropods. Most claims that sauropods could swim have been based on manus-only or manus-dominated trackways. However none of these incomplete trackways has been entirely convincing, and most have proved to be taphonomic artifacts, either undertracks or the result of differential depth of penetration of manus and pes tracks, but otherwise showed the typical pattern of normal walking trackways. Here we report an assemblage of unusual sauropod tracks from the Lower Cretaceous Hekou Group of Gansu Province, northern China, characterized by the preservation of only the pes claw traces, that we interpret as having been left by walking, not buoyant or swimming, individuals. They are interpreted as the result of animals moving on a soft mud-silt substrate, projecting their claws deeply to register their traces on an underlying sand layer where they gained more grip during progression. Other sauropod walking trackways on the same surface with both pes and manus traces preserved, were probably left earlier on relatively firm substrates that predated the deposition of soft mud and silt . Presently, there is no convincing evidence of swimming sauropods from their trackways, which is not to say that sauropods did not swim at all.
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http://dx.doi.org/10.1038/srep21138DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4758031PMC
February 2016

Theropod courtship: large scale physical evidence of display arenas and avian-like scrape ceremony behaviour by Cretaceous dinosaurs.

Sci Rep 2016 Jan 7;6:18952. Epub 2016 Jan 7.

Bureau of Land Management, Uncompahgre Field Office, 2465 S. Townsend Ave., 81401 Montrose, Colorado, 81401, USA.

Relationships between non-avian theropod dinosaurs and extant and fossil birds are a major focus of current paleobiological research. Despite extensive phylogenetic and morphological support, behavioural evidence is mostly ambiguous and does not usually fossilize. Thus, inferences that dinosaurs, especially theropods displayed behaviour analogous to modern birds are intriguing but speculative. Here we present extensive and geographically widespread physical evidence of substrate scraping behavior by large theropods considered as compelling evidence of "display arenas" or leks, and consistent with "nest scrape display" behaviour among many extant ground-nesting birds. Large scrapes, up to 2 m in diameter, occur abundantly at several Cretaceous sites in Colorado. They constitute a previously unknown category of large dinosaurian trace fossil, inferred to fill gaps in our understanding of early phases in the breeding cycle of theropods. The trace makers were probably lekking species that were seasonally active at large display arena sites. Such scrapes indicate stereotypical avian behaviour hitherto unknown among Cretaceous theropods, and most likely associated with terrirorial activity in the breeding season. The scrapes most probably occur near nesting colonies, as yet unknown or no longer preserved in the immediate study areas. Thus, they provide clues to paleoenvironments where such nesting sites occurred.
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http://dx.doi.org/10.1038/srep18952DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4704466PMC
January 2016
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