Feathers are remarkable evolutionary innovations that are associated with complex adaptations of the skin in modern birds. Fossilised feathers in non-avian dinosaurs and basal birds provide insights into feather evolution, but how associated integumentary adaptations evolved is unclear. Here we report the discovery of fossil skin, preserved with remarkable nanoscale fidelity, in three non-avian maniraptoran dinosaurs and a basal bird from the Cretaceous Jehol biota (China). The skin comprises patches of desquamating epidermal corneocytes that preserve a cytoskeletal array of helically coiled α-keratin tonofibrils. This structure confirms that basal birds and non-avian dinosaurs shed small epidermal flakes as in modern mammals and birds, but structural differences imply that these Cretaceous taxa had lower body heat production than modern birds. Feathered epidermis acquired many, but not all, anatomically modern attributes close to the base of the Maniraptora by the Middle Jurassic.

Evidence from iron meteorites indicates that a large number of differentiated planetesimals formed early in Solar System history. These bodies should have had well-developed olivine-rich mantles and consequentially such materials ought to be abundant both as asteroids and meteorites, which they are not. To investigate this "Great Dunite Shortage" we have undertaken a geochemical and oxygen isotope study of main-group pallasites and dunitic rocks from mesosiderites.Oxygen isotope analysis of 24 main-group pallasites (103 replicates) yielded a mean Delta O-17 value of -0.187 +/- 0.016 parts per thousand (2 sigma), which is fully resolved from the HED Delta O-17 value of -0.246 +/- 0.014 (2 sigma) obtained in our earlier study and demonstrates that both groups represent distinct populations and were derived from separate parent bodies. Our results show no evidence for Delta O-17 bimodality within the main-group pallasites, as suggested by a number of previous studies.Olivine-rich materials from the Vaca Muerta, Mount Padbury and Lamont mesosiderites, and from two related dunites (NWA 2968 and NWA 3329), have Delta O-17 values within error of the mesosiderite average. This indicates that these olivine-rich materials are co-genetic with other mesosiderite clasts and are not fragments from an isotopically distinct pallasite-like impactor. Despite its extreme lithologic diversity the mesosiderite parent body was essentially homogeneous with respect to Delta O-17, a feature best explained by an early phase of large-scale melting (magma ocean), followed by prolonged igneous differentiation.Based on the results of magma ocean modeling studies, we infer that Mg-rich olivines in mesosiderites formed as cumulates in high-level chambers and do not represent samples of the underlying mantle. By analogy, recently documented Mg-rich olivines in howardites may have a similar origin.Although the Dawn mission did not detect mesosiderite-like material on Vesta, evidence linking the mesosiderites and HEDs includes: (i) their nearly identical oxygen isotope compositions; (ii) the presence in both of coarse-grained Mg-rich olivines; (iii) both have synchronous Lu-Hf and Mn-Cr ages; (iv) there are compositional similarities between the metal in both; and (v) mesosiderite-like material has been identified in a howardite breccia. The source of the mesosiderites remains an outstanding question in meteorite science.The underrepresentation of olivine-rich materials amongst both asteroids and meteorites results from a range of factors. However, evidence from pallasites and mesosiderites indicates that the most important reason for this olivine shortage lies in the early, catastrophic destruction of planetesimals in the terrestrial planet-forming region and the subsequent preferential loss of their olivine-rich mantles. (C) 2015 The Authors. Published by Elsevier Ltd.

Cryptoendolithic lichen communities of the Dry Valleys, Antarctica, survive in an extremely inhospitable environment, finding refuge in microscopic niches where conditions suitable for life exist. Such "within-rock" communities may have evolved on Mars when conditions for life on the surface deteriorated to such an extent that they could no longer survive. Fourier transform infrared spectroscopy of unprepared whole-rock Antarctic Beacon sandstones was used to vertically profile molecular vibrations of fatty acids, proteins, and carboxylic acids created by endolithic communities. Spectral biosignatures were found localized to lichen-rich areas and were absent in crustal regions and the bulk rock substrate. These cryptoendolithic profiles will aid similar spectroscopic investigations of organic biosignatures during future Martian subsurface studies and will help in the identification of similar communities in other localities across the Earth.

Tube‐shaped beads excavated from grave pits at the prehistoric Gerzeh cemetery, approximately 3300 BCE, represent the earliest known use of iron in Egypt. Using a combination of scanning electron microscopy and micro X‐ray microcomputer tomography, we show that microstructural and chemical analysis of a Gerzeh iron bead is consistent with a cold‐worked iron meteorite. Thin fragments of parallel bands of taenite within a meteoritic Widmanstätten pattern are present, with structural distortion caused by cold‐working. The metal fragments retain their original chemistry of approximately 30 wt% nickel. The bulk of the bead is highly oxidized, with only approximately 2.4% of the total bead volume remaining as metal. Our results show that the first known example of the use of iron in Egypt was produced from a meteorite, its celestial origin having implications for both the perception of meteorite iron by ancient Egyptians and the development of metallurgical knowledge in the Nile Valley.

One of the earliest examples of iron used by man was discovered in a prehistoric Egyptian cemetery. The site of Gerzeh, 40 miles south of Cairo, was excavated in 1911-1912, over 300 graves dat-ing from around 3300 BCE were discovered [1]. A few of the graves contained rare and precious materials such as gold and lapis lazuli. Two graves, Tombs 67 and 133, were also found to contain iron beads; at the time of excavation these examples of Egyptian pre-dynastic culture were considered to be the earliest specimens of worked iron. Subsequent analysis revealed the iron to contain significant levels of nickel, leading to identification of their me-teoritic origin [3]. Iron meteorites were also used to make other items later in Egyptian history, including a dagger blade from Tutankhamen’s tomb (18th dynasty, 1340-1320 BCE), but no artefacts have been found to be made from meteorite iron after this date. The most recently published analysis of the Gerzeh iron beads was in 1929 [3]. Our study is intended as an illustration of the non-destructive analysis of an intact artifact, in order to allow a better understanding of this historically rare and precious sample. Optical imaging, electron microscopy and EDS were used to both define and analyze the bead. A thick weathering layer of oxidized iron was easily seen; this incorporates rounded quartz grains that originated in the grave, which was filled with sand. Patches of the oxidized areas have degraded and partially fallen away, probably post-excavation, allowing us to examine underlying regions in which small areas of metal were observed. The metal has an average composition of 9 wt. % Ni. The tubular bead structure interior was also found to be filled with ferric oxides and sand, at one end of the bead plant fibres of the strand used to string the beads together were also observed. This study explores one of the earliest examples of the use of meteoritic iron in artefacts. It is impossible to estimate the original mass of the meteorite: 9 beads were discovered in the two tombs, but because of the rarity of iron in early Egypt, it is assumed all beads were produced from the same meteorite. The meteorite must have fallen prior to approximately 3300 BCE, as this is the accepted date of the tombs. It is also possible that it fell beyond Egyptian borders as some of the other materials found in the tombs are believed to have arrived in Egypt through foreign trade routes.

The nakhlite meteorites, widely accepted to originate on Mars, preserve complex mixtures of silicate alteration, carbonates, sulphates, halides, oxides and iron oxyhydroxides. These phases may have formed at different times, under different fluid flow regimes (groundwater, hydrothermal, crater lake), experiencing a range of water-rock ratios, evaporative histories, and varying degrees of interaction with the atmosphere and bedrock. Using information gathered from our 3D investigations of Nakhla’s fluid pathways we have undertaken a range of insitu geochemical and isotopic analyses of carbonate, sulphate and halite in the Nakhla meteorite.

The colonization and weathering of young seafloor basaltic glass from the mid-Atlantic Ridge was examined. Microorganisms were localised to fractures in the surface of the basalt and grew on the surfaces of material in the fractures. XAS, Raman spectroscopy and NanoSIMS analysis of the fracture-filling material shows that it contains non-crystallised iron-enriched altered glass and poorly ordered iron oxides. Organisms, which in places develop into contiguous biofilms, develop on the surface of the material. No putative biogenic alteration textures were observed in the basaltic glass at the fracture boundaries suggesting that the microbial community is restricted to the secondary alteration products. Microbial culturing shows the presence of heterotrophic bacteria including Sufitobacter and Halomonas consistent with observations of photic zone detritus associated with fracture-filling material. These data show that the interior of fresh basaltic glass is an endolithic habitat for microorganisms, but that the glass itself is not a primary source of cations or energy for the developing communities.

Pallasites are frequently considered to have formed at core mantle boundaries within small asteroid bodies. This study employs LA-ICPMS, EMPA, SEM and optical microscopy to characterise a selection of main group pallasites, and the trace element abundances of kamacite to provide evidence of the relationship between members of the main group pallasites.

The two groups of enstatite chondrites (EH and EL) and aubrites, their differentiated counterparts, are a unique suite of specimens that formed under highly reducing conditions within the solar nebula, possibly on three separate parent bodies [1]. The reduced nature of the meteorites is shown by their unusual mineralogy, characterised by the presence of abundant sulphides. They also have the same oxygen isotopic signature as the Earth-Moon system [2]. This does not mean that Earth and enstatite meteorites formed from the same reservoir, but it suggests that they formed in a similar locality, i.e. the innermost part of the protoplanetary disk. If we wish to understand the formation and evolutionary history of the Solar System, then we must explain how the characteristics of the parental sources of enstatite meteorites fit in with other, more oxidized parents. To this end, we have been investigating the mineralogy of silicate and opaque(oxidised vs. reduced) phases within a suite of enstatite meteorites, including unequilibrated enstatite chondrites (UEC), as well as aubrites. We will match mineralogy with volatile content (as determined by a combination of ICP-MS and combustion MS techniques). UEC are little affected by thermal processes, and should preserve a record of volatile condensation under reducing conditions, although very little is known about the distribution and location of volatiles in UEC, as most of the compositional data available are for equilibrated enstatite chondrites [3].

A series of striking 'feathered dinosaur' fossil discoveries from the Cretaceous Jehol Group sediments of China has revolutionized thinking about the evolution and diversity of dinosaurs and early birds. But it has been suggested that some of the structures that are not obviously feathers might actually be strands of collagen from under the skin. Zhang et al. refute this notion by demonstrating the presence in these structures of melanosomes — the characteristic bodies that give feathers their colours. Not only do they show that the feather-like structures of dinosaurs such as Sinosauropteryx really are akin to feathers, but also they can speculate in an informed way about their colour — which it seems was reddish brown or ginger. Here the presence of melanosomes — characteristic bodies that give feathers their colour — is demonstrated in feathers and feather-like structures of fossil early birds and dinosaurs from the Early Cretaceous Jehol Group of China. Not only is it shown that the feather–like structures of dinosaurs such as Sinosauropteryx really are akin to feathers, it is also possible to speculate in an informed way about their colour. Spectacular fossils from the Early Cretaceous Jehol Group1,2 of northeastern China have greatly expanded our knowledge of the diversity and palaeobiology of dinosaurs and early birds, and contributed to our understanding of the origin of birds, of flight, and of feathers. Pennaceous (vaned) feathers and integumentary filaments are preserved in birds3,4,5 and non-avian theropod dinosaurs6,7,8,9,10,11,12, but little is known of their microstructure. Here we report that melanosomes (colour-bearing organelles) are not only preserved in the pennaceous feathers of early birds, but also in an identical manner in integumentary filaments of non-avian dinosaurs, thus refuting recent claims13,14,15,16 that the filaments are partially decayed dermal collagen fibres. Examples of both eumelanosomes and phaeomelanosomes have been identified, and they are often preserved in life position within the structure of partially degraded feathers and filaments. Furthermore, the data here provide empirical evidence for reconstructing the colours and colour patterning of these extinct birds and theropod dinosaurs: for example, the dark-coloured stripes on the tail of the theropod dinosaur Sinosauropteryx can reasonably be inferred to have exhibited chestnut to reddish-brown tones.

Introduction Pallasites are widely considered to be poor in sulphide, as such little is known about troilite evolution and processing. Very few examples exist indicating the multiple stages of troilite evolution. Discussed here are two such samples of FeS structures one is a nickel enriched FeS grain in the main group pallasite Hambleton. The other is a series of micron FeS particles within olivine crystals lying along partially annealed fractures in NWA4482. Discussion Hambleton- Is a main group pallasite rich in FeS, previous study [1] has illustrated this sulphide as interconnecting veins and sheets contained within these are typically broken frag-ments of olivine and chromite. Many of these Troilite veins dis-play a nickel enriched exsolution texture on a scale of hundreds of microns. We have now also identified a nickel enriched FeS grain within a later FeS vein, the grain displays a nickel enriched exsolution texture on a scale orders of magnitude smaller than that observed in vein structures. It is possible that the nickel en-richment within the veins is the result of melting of small frag-ments of nickel rich precursor FeS materials. This may implies that the grain evolved from a chemically distinct nickel rich melt either within the same parent body or seperately and subse-quently mixed. NWA4482- Is a highly weathered main group pallasite consisting of many fragments of a magnetic metal oxide-olivine meteorite. Most metal in this sample was weathered into iron hydroxides it was also found to contain small quantities of schreibersite and chromite grains. Only a small quantity of troilite was identified within the sample analysed it was embedded ex-clusively as particles within olivine crystals. The commonest of these particles are submicron size spheres distributed in equally spaced arrays that appear to lie along annealed fractures. Similar structures have been noted by others in olivine crystals within the Omolon pallasite [2] and were interpreted as indicator of post deformational annealing [3] or due to terrestrial atmospheric en-try and impact mechanisms. Arrays of tubular structures were also noted by others [4] in the main group pallasite Fukang they were attributed to exsolution of incompatible elements. Conclusion The observation of pre-cursor FeS structures may yield evidence to early formation processes in the pallasite parent bodies in relation to distribution of sulphide. The struc-tures identified in these two samples are supportive of Hambleton forming via introduction of a significant sulphide volume under pressure into a metal-olivine mixture with metal approaching solidus temperature, deforming olivine, chromite and pre-cursor FeS during the processes. The arrays of sulphide present in NWA4482 are most probably due to exsolution during formation. Further studies of both these structures could yield new insights into the formation process. References [1] Johnson D et al 2008 Meteoritics and Plane-tary Science, 43, A67 [2] Sharygin V.V et al. 2006 LPS XXVII A1235 [3] Buseck P R 1977, Geochim Cosmochim. Acta, 41,711 [4] Stevens M, Buseck P R, 2008 LPS XXXIX, A2157.

The application of X-ray microtomography to the sulphide rich main group pallasite Hambleton is dicussed as an attempt to further understand pallasite genesis. X-ray microtomography is an under utilized technique for the study of diverse samples such as pallasites. The three-dimensional textures observed in Hambleton may be explained by introduction of a large sulphide volume under pressure into a metal-olivine mixture with metal approaching solidus temperature.