Publications by authors named "Thomas G Kaye"

20 Publications

  • Page 1 of 1

Burmese Amber Compared Using Micro-Attenuated Total Reflection Infrared Spectroscopy and Ultraviolet Imaging.

Appl Spectrosc 2021 Jan 21:3702820986880. Epub 2021 Jan 21.

536920GRS Gemresearch Swisslab AG, Meggen (LU), Switzerland.

Attenuated Total Reflection (ATR) spectroscopy coupled with a microscope allows for the analysis of specimens without any preparation, spatially correlated with the morphology of the specimen. These characteristics make micro-ATR systems very useful for studying gemstones and in particular amber samples. Indeed, in this report, the micro-ATR technique was used to characterize three Burmite samples, as case studies. Particularly, focusing the ATR crystal spot on the amber surface where a difference in the Ultraviolet (UV) reaction was previously detected, thereby relative differences in the IR spectrum could be analyzed. Here we present a methodology combining the UV imaging technique with the micro-Attenuated total reflection Fourier transform infrared spectroscopy (micro-ATR/FT-IR) analyses, in order to correlate the fluorescence information with the molecular vibrational modes of amber and their relative spatial distribution. Finally, this work is intended as an initial methodology study and part of the amber characterization project, focused on characterizing the Burmese amber collection of the Peretti Museum Foundation from several disciplines (i.e., palaeoentomology, vibrational spectroscopy, neutron tomography, etc.).
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http://dx.doi.org/10.1177/0003702820986880DOI Listing
January 2021

Aerodynamics Show Membrane-Winged Theropods Were a Poor Gliding Dead-end.

iScience 2020 Dec 22;23(12):101574. Epub 2020 Oct 22.

Institute of Geology and Paleontology, Linyi University, Linyi City, Shandong, China.

The bizarre scansoriopterygid theropods and had skin stretched between elongate fingers that form a potential membranous wing. This wing is thought to have been used in aerial locomotion, but this has never been tested. Using laser-stimulated fluorescence imaging, we re-evaluate their anatomy and perform aerodynamic calculations covering flight potential, other wing-based behaviors, and gliding capabilities. We find that and were likely arboreal, highly unlikely to have any form of powered flight, and had significant deficiencies in flapping-based locomotion and limited gliding abilities. Our results show that Scansoriopterygidae are not models for the early evolution of bird flight, and their structurally distinct wings differed greatly from contemporaneous paravians, supporting multiple independent origins of flight. We propose that Scansoriopterygidae represents a unique but failed flight architecture of non-avialan theropods and that the evolutionary race to capture vertebrate aerial morphospace in the Middle to Late Jurassic was dynamic and complex.
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http://dx.doi.org/10.1016/j.isci.2020.101574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756141PMC
December 2020

Archaeopteryx feather sheaths reveal sequential center-out flight-related molting strategy.

Commun Biol 2020 Dec 8;3(1):745. Epub 2020 Dec 8.

Wyoming Dinosaur Center, Thermopolis, WY, 82443, USA.

Modern flying birds molt to replace old and worn feathers that inhibit flight performance, but its origins are unclear. We address this by presenting and evaluating a ~150 million year old record of molting in a feathered dinosaur from the early bird Archaeopteryx. Laser-Stimulated Fluorescence revealed feather sheaths that are otherwise invisible under white light. These are separated by one feather and are not in numerical sequential order and are mirrored in both wings. This indicates that a sequential center-out molting strategy was already present at the origins of flight, which is used in living falcons to preserve maximum flight performance. This strategy would have been a welcome advantage for early theropod flyers that had poor flight capabilities. This discovery provides important insights into how birds refined their early flight capabilities before the appearance of the keeled sternum, pygostyle and triosseal canal.
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http://dx.doi.org/10.1038/s42003-020-01467-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7722847PMC
December 2020

Reanalysis of putative ovarian follicles suggests that Early Cretaceous birds were feeding not breeding.

Sci Rep 2020 11 4;10(1):19035. Epub 2020 Nov 4.

LWL-Museum of Natural History, Westphalian State Museum with Planetarium, Sentruper Straße 285, 48161, Münster, Germany.

We address the identity of putative ovarian follicles in Early Cretaceous bird fossils from the Jehol Biota (China), whose identification has previously been challenged. For the first time, we present a link to the botanical fossil record, showing that the "follicles" of some enantiornithine fossils resemble plant propagules from the Jehol Biota, which belong to Carpolithes multiseminalis. The botanical affinities of this "form-taxon" are currently unresolved, but we note that C. multiseminalis propagules resemble propagules associated with cone-like organs described as Strobilites taxusoides, which in turn are possibly associated with sterile foliage allocated to Liaoningcladus. Laser-Stimulated Fluorescence imaging furthermore reveals different intensities of fluorescence of "follicles" associated with a skeleton of the confuciusornithid Eoconfuciusornis zhengi, with a non-fluorescent circular micro-pattern indicating carbonaceous (or originally carbonaceous) matter. This is inconsistent with the interpretation of these structures as ovarian follicles. We therefore reaffirm that the "follicles" represent ingested food items, and even though the exact nature of the Eoconfuciusornis stomach contents remains elusive, at least some enantiornithines ingested plant propagules.
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http://dx.doi.org/10.1038/s41598-020-76078-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7643104PMC
November 2020

Reply to: No protofeathers on pterosaurs.

Nat Ecol Evol 2020 12 28;4(12):1592-1593. Epub 2020 Sep 28.

School of Earth Sciences, University of Bristol, Bristol, UK.

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http://dx.doi.org/10.1038/s41559-020-01309-8DOI Listing
December 2020

Disassociated rhamphotheca of fossil bird Confuciusornis informs early beak reconstruction, stress regime, and developmental patterns.

Commun Biol 2020 Sep 21;3(1):519. Epub 2020 Sep 21.

Institute of Geology and Paleontology, Linyi University, Linyi, 276000, Shandong, China.

Soft tissue preservation in fossil birds provides a rare window into their anatomy, function, and development. Here, we present an exceptionally-preserved specimen of Confuciusornis which, through Laser-Stimulated Fluorescence imaging, is identified as preserving a disassociated rhamphotheca. Reconstruction of the in vivo position of the rhamphotheca validates the association of the rhamphotheca with two previous confuciusornithid specimens while calling that of a third specimen into question. The ease of dissociation is discussed and proposed with a fourth specimen alongside finite element analysis as evidence for preferential soft-food feeding. However, this proposition remains tentative until there is a better understanding of the functional role of beak attachment in living birds. Differences in post-rostral extent and possibly rhamphotheca curvature between confuciusornithids and modern birds hint at developmental differences between the two. Together, this information provides a wealth of new information regarding the nature of the beak outside crown Aves.
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http://dx.doi.org/10.1038/s42003-020-01252-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7506531PMC
September 2020

A giant planet candidate transiting a white dwarf.

Nature 2020 09 16;585(7825):363-367. Epub 2020 Sep 16.

Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA, USA.

Astronomers have discovered thousands of planets outside the Solar System, most of which orbit stars that will eventually evolve into red giants and then into white dwarfs. During the red giant phase, any close-orbiting planets will be engulfed by the star, but more distant planets can survive this phase and remain in orbit around the white dwarf. Some white dwarfs show evidence for rocky material floating in their atmospheres, in warm debris disks or orbiting very closely, which has been interpreted as the debris of rocky planets that were scattered inwards and tidally disrupted. Recently, the discovery of a gaseous debris disk with a composition similar to that of ice giant planets demonstrated that massive planets might also find their way into tight orbits around white dwarfs, but it is unclear whether these planets can survive the journey. So far, no intact planets have been detected in close orbits around white dwarfs. Here we report the observation of a giant planet candidate transiting the white dwarf WD 1856+534 (TIC 267574918) every 1.4 days. We observed and modelled the periodic dimming of the white dwarf caused by the planet candidate passing in front of the star in its orbit. The planet candidate is roughly the same size as Jupiter and is no more than 14 times as massive (with 95 per cent confidence). Other cases of white dwarfs with close brown dwarf or stellar companions are explained as the consequence of common-envelope evolution, wherein the original orbit is enveloped during the red giant phase and shrinks owing to friction. In this case, however, the long orbital period (compared with other white dwarfs with close brown dwarf or stellar companions) and low mass of the planet candidate make common-envelope evolution less likely. Instead, our findings for the WD 1856+534 system indicate that giant planets can be scattered into tight orbits without being tidally disrupted, motivating the search for smaller transiting planets around white dwarfs.
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http://dx.doi.org/10.1038/s41586-020-2713-yDOI Listing
September 2020

Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds.

Curr Biol 2020 Oct 6;30(20):4033-4046.e8. Epub 2020 Aug 6.

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

Uncertainties in the phylogeny of birds (Avialae) and their closest relatives have impeded deeper understanding of early theropod flight. To help address this, we produced an updated evolutionary hypothesis through an automated analysis of the Theropod Working Group (TWiG) coelurosaurian phylogenetic data matrix. Our larger, more resolved, and better-evaluated TWiG-based hypothesis supports the grouping of dromaeosaurids + troodontids (Deinonychosauria) as the sister taxon to birds (Paraves) and the recovery of Anchiornithinae as the earliest diverging birds. Although the phylogeny will continue developing, our current results provide a pertinent opportunity to evaluate what we know about early theropod flight. With our results and available data for vaned feathered pennaraptorans, we estimate the potential for powered flight among early birds and their closest relatives. We did this by using an ancestral state reconstruction analysis calculating maximum and minimum estimates of two proxies of powered flight potential-wing loading and specific lift. These results confirm powered flight potential in early birds but its rarity among the ancestors of the closest avialan relatives (select unenlagiine and microraptorine dromaeosaurids). For the first time, we find a broad range of these ancestors neared the wing loading and specific lift thresholds indicative of powered flight potential. This suggests there was greater experimentation with wing-assisted locomotion before theropod flight evolved than previously appreciated. This study adds invaluable support for multiple origins of powered flight potential in theropods (≥3 times), which we now know was from ancestors already nearing associated thresholds, and provides a framework for its further study. VIDEO ABSTRACT.
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http://dx.doi.org/10.1016/j.cub.2020.06.105DOI Listing
October 2020

Diatoms constrain forensic burial timelines: case study with DB Cooper money.

Sci Rep 2020 08 3;10(1):13036. Epub 2020 Aug 3.

, 228 Byron St, Palo Alto, CA, 94301, USA.

Diatoms are found universally in waters around the world. Some diatom species such as Asterionella formosa have a broad variation in seasonal abundance leading to the possibility that diatoms could constrain the time of year when an object was immersed in water. Here we apply this technique to the cold case of DB Cooper's money. Nine years after the crime, six thousand dollars in three bundles were found on the shore of the Columbia River near Portland, Oregon. This burial site was ~30 km from his reported jump location which gave no apparent reason for the money to end up there. This study found diatoms on a recovered bill which indicates that the money was immersed before burial. The species mix found on the bills was compared to a test bill submerged in the Columbia River in November which was the timeframe for the crime. The Cooper bill contained diatoms from summer bloom species suggesting that the money was not directly buried dry and the immersion happened months after the late November hijacking. This finding rules out of a majority of current theories related to the crime and proposes diatoms as a feasible methodology to constrain seasonal timelines in forensics.
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http://dx.doi.org/10.1038/s41598-020-70015-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400570PMC
August 2020

Recent advances in amniote palaeocolour reconstruction and a framework for future research.

Biol Rev Camb Philos Soc 2019 Sep 19. Epub 2019 Sep 19.

Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xizhimenwai Street., Beijing, 100044, China.

Preserved melanin pigments have been discovered in fossilised integumentary appendages of several amniote lineages (fishes, frogs, snakes, marine reptiles, non-avialan dinosaurs, birds, and mammals) excavated from lagerstätten across the globe. Melanisation is a leading factor in organic integument preservation in these fossils. Melanin in extant vertebrates is typically stored in rod- to sphere-shaped, lysosome-derived, membrane-bound vesicles called melanosomes. Black, dark brown, and grey colours are produced by eumelanin, and reddish-brown colours are produced by phaeomelanin. Specific morphotypes and nanostructural arrangements of melanosomes and their relation to the keratin matrix in integumentary appendages create the so-called 'structural colours'. Reconstruction of colour patterns in ancient animals has opened an exciting new avenue for studying their life, behaviour and ecology. Modern relationships between the shape, arrangement, and size of avian melanosomes, melanin chemistry, and feather colour have been applied to reconstruct the hues and colour patterns of isolated feathers and plumages of the dinosaurs Anchiornis, Sinosauropteryx, and Microraptor in seminal papers that initiated the field of palaeocolour reconstruction. Since then, further research has identified countershading camouflage patterns, and informed subsequent predictions on the ecology and behaviour of these extinct animals. However, palaeocolour reconstruction remains a nascent field, and current approaches have considerable potential for further refinement, standardisation, and expansion. This includes detailed study of non-melanic pigments that might be preserved in fossilised integuments. A common issue among existing palaeocolour studies is the lack of contextualisation of different lines of evidence and the wide variety of techniques currently employed. To that end, this review focused on fossil amniotes: (i) produces an overarching framework that appropriately reconstructs palaeocolour by accounting for the chemical signatures of various pigments, morphology and local arrangement of pigment-bearing vesicles, pigment concentration, macroscopic colour patterns, and taphonomy; (ii) provides background context for the evolution of colour-producing mechanisms; and (iii) encourages future efforts in palaeocolour reconstructions particularly of less-studied groups such as non-dinosaur archosaurs and non-archosaur amniotes.
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http://dx.doi.org/10.1111/brv.12552DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7004074PMC
September 2019

Cretaceous dinosaur bone contains recent organic material and provides an environment conducive to microbial communities.

Elife 2019 06 18;8. Epub 2019 Jun 18.

Department of Geosciences, Princeton University, Princeton, United States.

Fossils were thought to lack original organic molecules, but chemical analyses show that some can survive. Dinosaur bone has been proposed to preserve collagen, osteocytes, and blood vessels. However, proteins and labile lipids are diagenetically unstable, and bone is a porous open system, allowing microbial/molecular flux. These 'soft tissues' have been reinterpreted as biofilms. Organic preservation versus contamination of dinosaur bone was examined by freshly excavating, with aseptic protocols, fossils and sedimentary matrix, and chemically/biologically analyzing them. Fossil 'soft tissues' differed from collagen chemically and structurally; while degradation would be expected, the patterns observed did not support this. 16S rRNA amplicon sequencing revealed that dinosaur bone hosted an abundant microbial community different from lesser abundant communities of surrounding sediment. Subsurface dinosaur bone is a relatively fertile habitat, attracting microbes that likely utilize inorganic nutrients and complicate identification of original organic material. There exists potential post-burial taphonomic roles for subsurface microorganisms.
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http://dx.doi.org/10.7554/eLife.46205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6581507PMC
June 2019

Fully fledged enantiornithine hatchling revealed by Laser-Stimulated Fluorescence supports precocial nesting behavior.

Sci Rep 2019 03 21;9(1):5006. Epub 2019 Mar 21.

Facultad de Ciencias, Departamento de Biología, Universidad Autónoma de Madrid, 28049, Madrid, Spain.

Laser-Stimulated Fluorescence (LSF) is used to identify fully fledged feathering in the hatchling enantiornithine bird specimen MPCM-LH-26189, supporting precocial nesting behavior in this extinct group. The LSF results include the detection of a long pennaceous wing feather as well as cover feathers around the body. The LSF technique showed improved detection limits over and above synchrotron and UV imaging which had both been performed on this specimen. The findings underscore the value of using a wide range of analytical techniques.
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http://dx.doi.org/10.1038/s41598-019-41423-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6428842PMC
March 2019

Detection of lost calamus challenges identity of isolated Archaeopteryx feather.

Sci Rep 2019 02 4;9(1):1182. Epub 2019 Feb 4.

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

In 1862, a fossil feather from the Solnhofen quarries was described as the holotype of the iconic Archaeopteryx lithographica. The isolated feather's identification has been problematic, and the fossil was considered either a primary, secondary or, most recently, a primary covert. The specimen is surrounded by the 'mystery of the missing quill'. The calamus described in the original paper is unseen today, even under x-ray fluorescence and UV imaging, challenging its original existence. We answer this question using Laser-Stimulated Fluorescence (LSF) through the recovery of the geochemical halo from the original calamus matching the published description. Our study therefore shows that new techniques applied to well-studied iconic fossils can still provide valuable insights. The morphology of the complete feather excludes it as a primary, secondary or tail feather of Archaeopteryx. However, it could be a covert or a contour feather, especially since the latter are not well known in Archaeopteryx. The possibility remains that it stems from a different feathered dinosaur that lived in the Solnhofen Archipelago. The most recent analysis of the isolated feather considers it to be a primary covert. If this is the case, it lacks a distinct s-shaped centerline found in modern primary coverts that appears to be documented here for the first time.
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http://dx.doi.org/10.1038/s41598-018-37343-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362147PMC
February 2019

Pterosaur integumentary structures with complex feather-like branching.

Nat Ecol Evol 2019 01 17;3(1):24-30. Epub 2018 Dec 17.

Department of Earth Sciences, University of Bristol, Bristol, UK.

Pterosaurs were the first vertebrates to achieve true flapping flight, but in the absence of living representatives, many questions concerning their biology and lifestyle remain unresolved. Pycnofibres-the integumentary coverings of pterosaurs-are particularly enigmatic: although many reconstructions depict fur-like coverings composed of pycnofibres, their affinities and function are not fully understood. Here, we report the preservation in two anurognathid pterosaur specimens of morphologically diverse pycnofibres that show diagnostic features of feathers, including non-vaned grouped filaments and bilaterally branched filaments, hitherto considered unique to maniraptoran dinosaurs, and preserved melanosomes with diverse geometries. These findings could imply that feathers had deep evolutionary origins in ancestral archosaurs, or that these structures arose independently in pterosaurs. The presence of feather-like structures suggests that anurognathids, and potentially other pterosaurs, possessed a dense filamentous covering that probably functioned in thermoregulation, tactile sensing, signalling and aerodynamics.
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http://dx.doi.org/10.1038/s41559-018-0728-7DOI Listing
January 2019

Basal paravian functional anatomy illuminated by high-detail body outline.

Nat Commun 2017 03 1;8:14576. Epub 2017 Mar 1.

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

Body shape is a fundamental expression of organismal biology, but its quantitative reconstruction in fossil vertebrates is rare. Due to the absence of fossilized soft tissue evidence, the functional consequences of basal paravian body shape and its implications for the origins of avians and flight are not yet fully understood. Here we reconstruct the quantitative body outline of a fossil paravian Anchiornis based on high-definition images of soft tissues revealed by laser-stimulated fluorescence. This body outline confirms patagia-bearing arms, drumstick-shaped legs and a slender tail, features that were probably widespread among paravians. Finely preserved details also reveal similarities in propatagial and footpad form between basal paravians and modern birds, extending their record to the Late Jurassic. The body outline and soft tissue details suggest significant functional decoupling between the legs and tail in at least some basal paravians. The number of seemingly modern propatagial traits hint that feathering was a significant factor in how basal paravians utilized arm, leg and tail function for aerodynamic benefit.
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http://dx.doi.org/10.1038/ncomms14576DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5339877PMC
March 2017

Laser Fluorescence Illuminates the Soft Tissue and Life Habits of the Early Cretaceous Bird Confuciusornis.

PLoS One 2016 14;11(12):e0167284. Epub 2016 Dec 14.

University of Kansas Natural History Museum and Biodiversity Institute, Lawrence, KS United States of America.

In this paper we report the discovery of non-plumage soft tissues in Confuciusornis, a basal beaked bird from the Early Cretaceous Jehol Biota in northeastern China. Various soft tissues are visualized and interpreted through the use of laser-stimulated fluorescence, providing much novel anatomical information about this early bird, specifically reticulate scales covering the feet, and the well-developed and robust pro- and postpatagium. We also include a direct comparison between the forelimb soft tissues of Confuciusornis and modern avian patagia. Furthermore, apparently large, fleshy phalangeal pads are preserved on the feet. The reticulate scales, robust phalangeal pads as well as the highly recurved pedal claws strongly support Confuciusornis as an arboreal bird. Reticulate scales are more rounded than scutate scales and do not overlap, thus allowing for more flexibility in the toe. The extent of the pro- and postpatagium and the robust primary feather rachises are evidence that Confuciusornis was capable of powered flight, contrary to previous reports suggesting otherwise. A unique avian wing shape is also reconstructed based on plumage preserved. These soft tissues combined indicate an arboreal bird with the capacity for short-term (non-migratory) flight, and suggest that, although primitive, Confuciusornis already possessed many relatively advanced avian anatomical characteristics.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0167284PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5156344PMC
July 2017

3D Camouflage in an Ornithischian Dinosaur.

Curr Biol 2016 09 15;26(18):2456-2462. Epub 2016 Sep 15.

School of Biological Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK. Electronic address:

Countershading was one of the first proposed mechanisms of camouflage [1, 2]. A dark dorsum and light ventrum counteract the gradient created by illumination from above, obliterating cues to 3D shape [3-6]. Because the optimal countershading varies strongly with light environment [7-9], pigmentation patterns give clues to an animal's habitat. Indeed, comparative evidence from ungulates [9] shows that interspecific variation in countershading matches predictions: in open habitats, where direct overhead sunshine dominates, a sharp dark-light color transition high up the body is evident; in closed habitats (e.g., under forest canopy), diffuse illumination dominates and a smoother dorsoventral gradation is found. We can apply this approach to extinct animals in which the preservation of fossil melanin allows reconstruction of coloration [10-15]. Here we present a study of an exceptionally well-preserved specimen of Psittacosaurus sp. from the Chinese Jehol biota [16, 17]. This Psittacosaurus was countershaded [16] with a light underbelly and tail, whereas the chest was more pigmented. Other patterns resemble disruptive camouflage, whereas the chin and jugal bosses on the face appear dark. We projected the color patterns onto an anatomically accurate life-size model in order to assess their function experimentally. The patterns are compared to the predicted optimal countershading from the measured radiance patterns generated on an identical uniform gray model in direct versus diffuse illumination. These studies suggest that Psittacosaurus sp. inhabited a closed habitat such as a forest with a relatively dense canopy. VIDEO ABSTRACT.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5049543PMC
http://dx.doi.org/10.1016/j.cub.2016.06.065DOI Listing
September 2016

Laser-stimulated fluorescence in paleontology.

PLoS One 2015 27;10(5):e0125923. Epub 2015 May 27.

1111 Army Navy Drive, Arlington, Virginia, United States of America.

Fluorescence using ultraviolet (UV) light has seen increased use as a tool in paleontology over the last decade. Laser-stimulated fluorescence (LSF) is a next generation technique that is emerging as a way to fluoresce paleontological specimens that remain dark under typical UV. A laser's ability to concentrate very high flux rates both at the macroscopic and microscopic levels results in specimens fluorescing in ways a standard UV bulb cannot induce. Presented here are five paleontological case histories that illustrate the technique across a broad range of specimens and scales. Novel uses such as back-lighting opaque specimens to reveal detail and detection of specimens completely obscured by matrix are highlighted in these examples. The recent cost reductions in medium-power short wavelength lasers and use of standard photographic filters has now made this technique widely accessible to researchers. This technology has the potential to automate multiple aspects of paleontology, including preparation and sorting of microfossils. This represents a highly cost-effective way to address paleontology's preparatory bottleneck.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0125923PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4446324PMC
April 2016

Lakeside cemeteries in the Sahara: 5000 years of holocene population and environmental change.

PLoS One 2008 Aug 14;3(8):e2995. Epub 2008 Aug 14.

Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, United States of America.

Background: Approximately two hundred human burials were discovered on the edge of a paleolake in Niger that provide a uniquely preserved record of human occupation in the Sahara during the Holocene ( approximately 8000 B.C.E. to the present). Called Gobero, this suite of closely spaced sites chronicles the rapid pace of biosocial change in the southern Sahara in response to severe climatic fluctuation.

Methodology/principal Findings: Two main occupational phases are identified that correspond with humid intervals in the early and mid-Holocene, based on 78 direct AMS radiocarbon dates on human remains, fauna and artifacts, as well as 9 OSL dates on paleodune sand. The older occupants have craniofacial dimensions that demonstrate similarities with mid-Holocene occupants of the southern Sahara and Late Pleistocene to early Holocene inhabitants of the Maghreb. Their hyperflexed burials compose the earliest cemetery in the Sahara dating to approximately 7500 B.C.E. These early occupants abandon the area under arid conditions and, when humid conditions return approximately 4600 B.C.E., are replaced by a more gracile people with elaborated grave goods including animal bone and ivory ornaments.

Conclusions/significance: The principal significance of Gobero lies in its extraordinary human, faunal, and archaeological record, from which we conclude the following: The early Holocene occupants at Gobero (7700-6200 B.C.E.) were largely sedentary hunter-fisher-gatherers with lakeside funerary sites that include the earliest recorded cemetery in the Sahara.Principal components analysis of craniometric variables closely allies the early Holocene occupants at Gobero with a skeletally robust, trans-Saharan assemblage of Late Pleistocene to mid-Holocene human populations from the Maghreb and southern Sahara.Gobero was abandoned during a period of severe aridification possibly as long as one millennium (6200-5200 B.C.E).More gracile humans arrived in the mid-Holocene (5200-2500 B.C.E.) employing a diversified subsistence economy based on clams, fish, and savanna vertebrates as well as some cattle husbandry.Population replacement after a harsh arid hiatus is the most likely explanation for the occupational sequence at Gobero.We are just beginning to understand the anatomical and cultural diversity that existed within the Sahara during the Holocene.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0002995PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2515196PMC
August 2008

Dinosaurian soft tissues interpreted as bacterial biofilms.

PLoS One 2008 Jul 30;3(7):e2808. Epub 2008 Jul 30.

Department of Paleontology, Burke Museum of Natural History, Seattle, Washington, United States of America.

A scanning electron microscope survey was initiated to determine if the previously reported findings of "dinosaurian soft tissues" could be identified in situ within the bones. The results obtained allowed a reinterpretation of the formation and preservation of several types of these "tissues" and their content. Mineralized and non-mineralized coatings were found extensively in the porous trabecular bone of a variety of dinosaur and mammal species across time. They represent bacterial biofilms common throughout nature. Biofilms form endocasts and once dissolved out of the bone, mimic real blood vessels and osteocytes. Bridged trails observed in biofilms indicate that a previously viscous film was populated with swimming bacteria. Carbon dating of the film points to its relatively modern origin. A comparison of infrared spectra of modern biofilms with modern collagen and fossil bone coatings suggests that modern biofilms share a closer molecular make-up than modern collagen to the coatings from fossil bones. Blood cell size iron-oxygen spheres found in the vessels were identified as an oxidized form of formerly pyritic framboids. Our observations appeal to a more conservative explanation for the structures found preserved in fossil bone.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0002808PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2483347PMC
July 2008