Archaeopteryx feathers and bone chemistry fully revealed via synchrotron imaging

Abstract

Evolution of flight in maniraptoran dinosaurs is marked by the acquisition of distinct avian characters, such as feathers, as seen in Archaeopteryx from the Solnhofen limestone. These rare fossils were pivotal in confirming the dinosauria-avian lineage. One of the key derived avian characters is the possession of feathers, details of which were remarkably preserved in the Lagerstätte environment. These structures were previously simply assumed to be impressions; however, a detailed chemical analysis has, until now, never been completed on any Archaeopteryx specimen. Here we present chemical imaging via synchrotron rapid scanning X-ray fluorescence (SRS-XRF) of the Thermopolis Archaeopteryx, which shows that portions of the feathers are not impressions but are in fact remnant body fossil structures, maintaining elemental compositions that are completely different from the embedding geological matrix. Our results indicate phosphorous and sulfur retention in soft tissue as well as trace metal (Zn and Cu) retention in bone. Other previously unknown chemical details of Archaeopteryx are also revealed in this study including: bone chemistry, taphonomy (fossilization process), and curation artifacts. SRS-XRF represents a major advancement in the study of the life chemistry and fossilization processes of Archaeopteryx and other extinct organisms because it is now practical to image the chemistry of large specimens rapidly at concentration levels of parts per million. This technique has wider application to the archaeological, forensic, and biological sciences, enabling the mapping of "unseen" compounds critical to understanding biological structures, modes of preservation, and environmental context. trace elements | X-ray absorption spectroscopy A rchaeopteryx (1) are rare but occupy a pivotal place in the development of Darwinian evolution because of their possession of both reptilian (jaws with teeth and a long bony tail) and avian (feathered wings) characters (2). The specimen used in this study is considered to be the most complete and best preserved archaeopterygid (3) belonging to the species A. siemensii (4). Previous analyses of this fossil have relied upon visual inspection, X-ray computer tomography, scanning electron, and ultraviolet/ visible light microscopy. Structural studies have been extensive and strongly indicate that this organism is transitional between dinosaurs and birds; however, detailed chemical analysis has never been performed. Here we apply state-of-the-art synchrotron rapid scanning X-ray fluorescence (SRS-XRF) imaging to this remarkably well-preserved specimen revealing striking and previously unknown details about the chemical preservation of soft tissue, elemental distribution patterns most likely related to the organism's life processes, insights into the chemistry of the fossilization process, and details of curation history. In addition, quantitative chemical analyses and X-ray absorption spectroscopy are presented that not only corroborate the imaging results but also give further det...

2D Neutron Diffraction Imaging on an Ammonite

“…For example, the molluscous parts are found in body chambers of Goniatite ammonites by using x-ray radiography [10]. In addition, feathers of an archaeopteryx fossil are observed by synchrotron fluorescence imaging of phosphorus due to the phosphorus-rich composition of her original feathers [12]. Therefore, siderite observed at the body chamber suggests that the molluscous part may consist of Mg and Fe rich chemical composition.…”

Informative Potential of Multiscale Observations in Archaeological Biominerals Down to Nanoscale

“…Nowadays, two and sometimes three-dimensional (2D and 3D) elemental, molecular, structural and isotopic imaging of entire objects has becomes possible owing to recent technological developments off ocused analytical probes used in scanning mode and detectors (e.g. Lebon et al 2011a;Reiche et al 2011aReiche et al , 2003Reiche et al , 2010Reiche and Chalmin 2008;Anne et al 2014;Bergmann et al 2010;Gueriau et al 2014;Gourrier et al 2007bGourrier et al , 2010.…”

The benefits of commercial fossil sales to 21st-century paleontology

“…This specimen has been displayed in Canada, China, Europe, Japan, and the US. It has been molded, photographed, Micro-CT scanned, laser-scanned and XRF scanned, and has generated multiple high-impact publications (Mayer et al 2005, Bergmann et al 2010. Despite this excellent academic work, some paleontologists have raised concerns on the ethics of publishing such material.…”

“…This site has been operated commercially since the advent of the lithographic printing process in 1798 (Barthel et al 1990). The Solnhofen Limestone has produced some of the most important fossils in the study of evolution, including the iconic early bird Archaeopteryx (Bergmann et al 2010). Every single specimen of Archaeopteryx known to science has been bought and sold (Ostrom 1985, Barthel et al 1990.…”