Bones of recent mammals in the Amboseli Basin, southern Kenya, exhibit distinctive weathering characteristics that can be related to the time since death and to the local conditions of temperature, humidity and soil chemistry. A categorization of weathering characteristics into six stages, recognizable on descriptive criteria, provides a basis for investigation of weathering rates and processes. The time necessary to achieve each successive weathering stage has been calibrated using known-age carcasses. Most bones decompose beyond recognition in 10 to 15 yr. Bones of animals under 100 kg and juveniles appear to weather more rapidly than bones of large animals or adults. Small-scale rather than widespread environmental factors seem to have greatest influence on weathering characteristics and rates. Bone weathering is potentially valuable as evidence for the period of time represented in recent or fossil bone assemblages, in- cluding those on archeological sites, and may also be an important tool in censusing populations of animals in modern ecosystems.

Taphonomic and Ecologic Information Form Bone Weathering

The Climate Near the Ground

A rapid and economical route based on an efficient microwave–hydrothermal process has been developed to synthesize monodisperse α-Fe2O3 nanocrystals with continuous aspect-ratio tuning and fine shape control, which takes advantage of microwave irradiation and hydrothermal effects. This method easily programs the experimental conditions (e.g., temperature and time) and significantly shortens the synthesis time to minutes. It allows the creation of numerous recipes for optimizing and scaling up production. The effects of experimental conditions including reaction temperature and reactant concentration on the morphology of α-Fe2O3 have been investigated systematically. Results reveal that the initial molar ratio of Fe3+ to PO plays a crucial role in the final morphology of the α-Fe2O3 products. Several morphologies, which include ellipsoids/spindles with aspect ratios that range from 1.1 to 6.3, nanosheets, nanorings, and spheres can be obtained. The as-formed α-Fe2O3 exhibits shape-dependent infrared optical properties. The growth process of colloidal α-Fe2O3 crystals in the presence of phosphate ions is discussed. The products have been characterized by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and infrared spectroscopy. This work presents an efficient and cost-effective approach that is potentially competitive for scaling-up industrial production. The as-formed α-Fe2O3 crystals with controllable morphologies not only provide flexible building blocks for advanced functional devices, but are also ideal candidates for studying their nanoarchitecture-dependent performance in optical, catalytic, and magnetic applications.

Continuous Aspect-Ratio Tuning and Fine Shape Control of Monodisperse α-Fe2O3 Nanocrystals by a Programmed Microwave-Hydrothermal Method

The search for affordable high performance electrode materials in photoelectrochemical hydrogen production by solar water splitting is an ongoing quest. Hematite is a photoanode material with an electronic band gap suitable for efficient absorption of visible light in a photoelectrochemical cell (PEC). Although its poor electronic structure makes hematite a controversial candidate for PEC, it remains promising because it is an earth abundant, chemically stable and low cost material – necessary prerequisites for PEC to become a competitive cost-efficient solar fuel economy. In addition to reviewing some recent PEC research on hematite and its relevant physical and chemical characteristics, we show how hematite obtained by a low cost synthesis can be refined by hydrothermal treatment and further functionalized by coating with phycocyanin, a light harvesting protein known for photosynthesis in blue-green algae.

“In rust we trust”. Hematite – the prospective inorganic backbone for artificial photosynthesis

We propose a simple method for the efficient and rapid synthesis of one-dimensional hematite (α-Fe2O3) nanostructures based on electrical resistive heating of iron wire under ambient conditions. Typically, 1–5 μm long α-Fe2O3 nanowires were synthesized on a time scale of seconds at temperatures of around 700 ° ⊂. The morphology, structure, and mechanism of formation of the nanowires were studied by scanning and transmission electron microscopies, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman techniques. A nanowire growth mechanism based on diffusion of iron ions to the surface through grain boundaries and to the growing wire tip through stacking fault defects and due to surface diffusion is proposed.

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Simple and rapid synthesis of α-Fe2O3 nanowires under ambient conditions

A new specimen of Supersaurus vivianae is described, providing additional information about the osteology of Supersaurus. The single Supersaurus individual that the WDC quarry produced allows a re- examination of elements referred to Supersaurus from the Dry Mesa quarry. The osteology supports maintaining the generic distinction of Supersaurus. Phylogenetic evaluation finds a monophyletic Apatosaurinae containing (Apatosaurus + Supersaurus) + Suuwassea, and a monophyletic Diplodocinae containing (Diplodocus + Seismosaurus) + Barosaurus, although the generic distinction of Seismosaurus is not supported in the current analysis. RESUMO: Morfologia de um especime de Supersaurus (Dinosauria, Sauropoda) da Formacao Morrison de Wyoming e uma reavaliacao da filogenia de diplodocideos. Um novo especime de Supersaurus vivianae e descrito, acrescentando informacoes sobre a osteologia de Supersaurus. O unico individuo de Supersaurus coletado no afloramento WDC permite o re-exame dos elementos referidos a Supersaurus do afloramento de Dry Mesa. A osteologia suporta a manutencao da distincao generica de Supersaurus. Uma avaliacao filogenetica resultou em um grupo monofiletico Apatosaurinae contendo (Apatosaurus + Supersaurus) + Suuwassea, e um grupo monofiletico Diplodocinae contendo (Diplodocus + Seismosaurus) + Barosaurus, embora a distincao generica de Seismosaurus nao esteja suportada na presente analise.

Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny

The last two decades have seen a remarkable increase in the known diversity of basal avialans and their paravian relatives. The lack of resolution in the relationships of these groups combined with attributing the behavior of specialized taxa to the base of Paraves has clouded interpretations of the origin of avialan flight. Here, we describe Hesperornithoides miessleri gen. et sp. nov., a new paravian theropod from the Morrison Formation (Late Jurassic) of Wyoming, USA, represented by a single adult or subadult specimen comprising a partial, well-preserved skull and postcranial skeleton. Limb proportions firmly establish Hesperornithoides as occupying a terrestrial, non-volant lifestyle. Our phylogenetic analysis emphasizes extensive taxonomic sampling and robust character construction, recovering the new taxon most parsimoniously as a troodontid close to Daliansaurus, Xixiasaurus, and Sinusonasus. Multiple alternative paravian topologies have similar degrees of support, but proposals of basal paravian archaeopterygids, avialan microraptorians, and Rahonavis being closer to Pygostylia than archaeopterygids or unenlagiines are strongly rejected. All parsimonious results support the hypothesis that each early paravian clade was plesiomorphically flightless, raising the possibility that avian flight originated as late as the Late Jurassic or Early Cretaceous.

A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight.

The Lower Triassic Red Peak Formation of the Chugwater Group has long been considered to have an extremely poor paleontological record, although the cause for the apparent dearth of fossils has yet to be been determined. During the course of fieldwork in central Wyoming numerous vertebrate and invertebrate ichnogenera (n ≥ 11) were observed. Vertebrate tracks and trackways representative of dinosauromorph, archosaur, lepidosaur, and testudinate trackmakers were found (cf. Rotodactylus, Chirotherium barthii, Rhynchosauroides, and cf. Chelonipus respectively). An invertebrate ichnoassemblage composed of at least 6 ichnogenera consistent with the Scoyenia ichnofacies were also found (e.g., Diplichnites, Lockeia, Fuersichnus communis, Palaeophycus striatus, cf. Scoyenia, and cf. Scolicia). The majority of these tracks and traces were found in the upper platy facies (upper 10–20 m of the of the Red Peak Formation), which is thought to be no younger than upper Spathian in age. Sedimentary structures, architectural elements, and lateral stratigraphic relationships support the interpretation of floodplain, fluvial, and lacustrine deposition for the upper platy facies in central Wyoming. The Red Peak Formation vertebrate and invertebrate ichnoassemblages, along with their associated depositional environments, are consistent with a fluviolacustrine (continental) setting comparable to those described from Lower to Middle Triassic strata with a Pangean distribution, including the Moenkopi Formation in the southwestern United States. This ichnoassemblage provides the first opportunity to observe paleoecological diversity and associated paleoenvironments within the Lower Triassic of the Chugwater Group.

https://bioone.org/journals/palaios/volume-27/issue-9/palo.2012.p12-011r/PALEOENVIRONMENTS-AND-PALEOECOLOGY-OF-A-LOWER-TRIASSIC-INVERTEBRATE-AND-VERTEBRATE/10.2110/palo.2012.p12-011r.pdf

Paleoenvironments and Paleoecology of a Lower Triassic Invertebrate and Vertebrate Ichnoassemblage from the Red Peak Formation (Chugwater Group), Central Wyoming

Turtle (Testudines) tracks, Chelonipus torquatus, reported from the early Middle Triassic (Anisian) of Germany, and Chelonipus isp. from the late Early Triassic (Spathian) of Wyoming and Utah, are the oldest fossil evidence of turtles, but have been omitted in recent discussions of turtle origins. These tracks provide significant clues as to how early the turtle Bauplan originated. Turtle trackways are quite distinctive: the manus and pes form tracks nearly parallel to the midline and indicate an unusually wide gait in which the trackway width is nearly equal to the stride length. These tracks do not fit what would be expected to be made by Triassic Pappochelys or Odontochelys, a supposed prototurtle and an early turtle, respectively. In contrast, these tracks are consistent with what would be expected from the Triassic turtles Proganochelys and Palaeochersis. The features inferred to be present in Triassic turtle tracks support the notion that Odontochelys is a derived aquatic branch of the turtl...

David M. Lovelace

Papers

Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny

A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight.

Paleoenvironments and Paleoecology of a Lower Triassic Invertebrate and Vertebrate Ichnoassemblage from the Red Peak Formation (Chugwater Group), Central Wyoming

Triassic turtle tracks and the origin of turtles

Cytochrome c interaction with hematite (α-Fe2O3) surfaces