Enpu Gong

Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui

Fossils of the remarkable dromaeosaurid Microraptor gui and relatives clearly show well-developed flight feathers on the hind limbs as well as the front limbs. No modern vertebrate has hind limbs functioning as independent, fully developed wings; so, lacking a living example, little agreement exists on the functional morphology or likely flight configuration of the hindwing. Using a detailed reconstruction based on the actual skeleton of one individual, cast in the round, we developed light-weight, three-dimensional physical models and performed glide tests with anatomically reasonable hindwing configurations. Models were tested with hindwings abducted and extended laterally, as well as with a previously described biplane configuration. Although the hip joint requires the hindwing to have at least 20° of negative dihedral (anhedral), all configurations were quite stable gliders. Glide angles ranged from 3° to 21° with a mean estimated equilibrium angle of 13.7°, giving a lift to drag ratio of 4.1:1 and a lift coefficient of 0.64. The abducted hindwing model’s equilibrium glide speed corresponds to a glide speed in the living animal of 10.6 m·s−1. Although the biplane model glided almost as well as the other models, it was structurally deficient and required an unlikely weight distribution (very heavy head) for stable gliding. Our model with laterally abducted hindwings represents a biologically and aerodynamically reasonable configuration for this four-winged gliding animal. M. gui’s feathered hindwings, although effective for gliding, would have seriously hampered terrestrial locomotion.

The birdlike raptor Sinornithosaurus was venomous

We suggest that some of the most avian dromaeosaurs, such as Sinornithosaurus, were venomous, and propose an ecological model for that taxon based on its unusual dentition and other cranial features including grooved teeth, a possible pocket for venom glands, and a groove leading from that pocket to the exposed bases of the teeth. These features are all analogous to the venomous morphology of lizards. Sinornithosaurus and related dromaeosaurs probably fed on the abundant birds of the Jehol forests during the Early Cretaceous in northeastern China.

Laser-Stimulated Fluorescence in Paleontology

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 paleontologys preparatory bottleneck.

Palynomorph assemblages and paleoclimate records from the Zhuanchengzi Bed of the Yixian Formation, western Liaoning Province, China

We collected, processed, identified, and analyzed the spores and pollen samples from the Zhuanchengzi Bed of the Yixian Formation in the Yingwoshan area of western Liaoning. As a result, we confirm a palynomorph assemblage of Cicatricosisporites-Protoconiferus. The pollen was primarily from gymnosperms, dominated especially by conifer pollen. Pteridophyte spores were less common and some questionable angiosperm pollen occurred occasionally. The age of the palynomorph assemblage is dated as the late Valanginian or Hauterivian-Barremian stage, the Early Cretaceous. The study applies the concept of Palynological Vegetation based on palynological spectra and the paleoecological characteristics of palynological taxa for the first time. Palynological vegetation type, climatic zone type, and humidity type are divided quantitatively for the Zhuanchengzi Bed in the Yixian Formation of western Liaoning. We then obtained the evolutionary trends. The results showed that the overall climate was warm and humid during the deposition period of the Zhuanchengzi Bed in the Yixian Formation. Palynological vegetation types are various and include coniferous forest, deciduous broadleaf forest, evergreen broad-leaved forest, grass, and shrubs. The local temperature changed from warm to much warmer and from a semi-humid to humid climate. Palynological vegetation types are always dominated by coniferous forest. The coexistence of deciduous broad-leaved forest, evergreen broad-leaved forest, shrubs, grass, and some xerophytic plants indicates vertical zonation and seasonal climate change The vertical vegetation types and the warm humid climate may imply a large geomorphological contrast in the Yixian Formation of western Liaoning.

A NEW EXPERIMENTAL SETUP FOR STUDYING AVIAN NEOICHNOLOGY AND THE EFFECTS OF GRAIN SIZE AND MOISTURE CONTENT ON TRACKS: TRIALS USING THE DOMESTIC CHICKEN (GALLUS GALLUS)

Abstract: A new experimental setup using a collapsible wooden tray, monopod, and digital video camera is used to observe and collect modern bird tracks. This setup is unique because it simultaneously captures tracemaker behavior, trace morphology, and media consistency (i.e., grain size and moisture content), and can be used in the laboratory and in natural environments. Here we provide examples produced by domestic chickens (Gallus gallus). Using this setup we determined that bird track morphology varies in a predictable manner with respect to sediment grain size and the percent of water present. The finer the sediment grain size, the more detail is likely to be preserved. If the sediment is completely dry, no track details will be preserved––digit impressions will be broad and will not taper at the tips; digit impression length will be longer than the actual digit lengths. If the sediment is wet (8.8%–6.7%), digit impressions will taper to points, will not be as wide as in dry sediment, and will not preserve pad impressions. If the sediment is variably moist (5.3%–3.2%), the detail level of pad or scale impressions, depending on the grain size, may be present. Within this study, we propose a sinuosity index that allows for quantification of sinuous avian trackways, and quantify the trackway parameters of behaviors, including start-stop walking, walking, running, takeoff, and landing. Both takeoff and landing traces are significantly deeper than the proceeding or following walking and running traces. Start-stop walking does not always result in side-by-side paired tracks, and often the bird will pause in midstride. Linking behavior and morphology of tracks can be used to better interpret ancient behavior and the depositional environment in which ancient tracks were produced.

Palaeoecology of Late Carboniferous encrusting chaetetids in North China

Well-preserved encrusting chaetetids are widespread and easily observed in limestones of the Benxi Formation (Moscovian, Upper Carboniferous) in the Benxi area, eastern Liaoning Province, North China. Chaetetids and colonial corals were the framework-building organisms, with chaetetids as the most common fossils in several small-scale reefs of the study area. The common types of hard substrate encrusted by chaetetids include in situ carbonate hardgrounds, carbonate hardground clasts, calcareous bioclasts and coral skeletons. We have observed lamellar, low domical (mini-domal) and anastomosing lamellar chaetetid morphologies in this fauna. Chaetetids with thin, spreading lamellae are the most common growth forms. Chaetetids employed peripheral, medial and mixed growth strategies to occupy sufficient living space on the substrates. They favoured a shallow, warm and clear marine environment within the photic zone. Chaetetids were later usually smothered by sediments. The chaetetid fossil communities in the Benxi area have a relatively high species diversity, which is not typical of hard substrate marine communities in the Carboniferous. The most common spatial relationship between competing encrusters on hard substrates is the growth of one over the other in the study region. Chaetetids were superior competitors for hard substrate attachment space. This palaeoecological study of chaetetids offers a new example for encrusting organisms on hard substrates of the Carboniferous of China. This research may aid in studying other colonised substrates of the Late Carboniferous.

The first report of terrestrial Petroxestes from the Lower Cretaceous Yixian Formation, western Liaoning, China

Abundant aggregated, elongate, shallow borings have been discovered from the Lower Cretaceous Yixian Formation in western Liaoning, China. By contrast with several similarly-shaped trace fossils, such as Asthenopodichnium, Teredolites, Rogerella, Cubiculum and Petroxestes, their appearance, size, arranged modes, distribution density and substrate types are most similar with traces of Petroxestes that was discovered from Southern Ohio, USA (J. Paleontol. 62: 306–08, 1988). This is the first report of Petroxestes from China, and also the first report of these traces from a terrestrial environment.