Saturday, 2 June 2012
Dinosaurs, Physics and the MET Museum of Art?
This week I head to a meeting in New York City. The meeting is being held at the Metropolitan Museum of Art (The 'MET' to many). The Synchrotron Radiation in Art and Archaeology (SR2A) meeting will explore the latest inroads for synchrotron-based research to these two disciplines...with a few stray palaeontological presentations to boot! My talk will try, in 30 minutes, to highlight some of the advances that the Stanford Synchrotron Radiation Lightsouce (SSRL) and University of Manchester team have been working on these past five years or more. 30 minutes is not a long time, so I will have to either speak very quickly or just focus on some of our key findings...I think the latter wins!
The talk is entitled, 'Mapping Prehistoric Ghosts in the Synchrotron' and like many such presentations is credited to key members of the team, myself, Roy Wogelius, Bill Sellers and Uwe Bergmann.
For those of you who want a sneak preview of the talk...here is my abstract:
Detailed chemical analyses have never been completed on any fossil bird, such as the remains of Archaeopteryx and Confuciuornis santus, despite their iconic status. Ideally such analyses would measure and map the chemistry of bone, soft tissue structures, and characterize embedding matrix. Mapping the fossil in situ would place constraints on mass transfer between the enclosing matrix and preserved specimen(s), and therefore aid in distinguishing taphonomic processes from original chemical zonation remnant within the fossils themselves. Conventional nondestructive analytical methods face serious problems in this case and most recent technological advances have been targeted at developing nanometer-scale rather than decimeter-scale capabilities. However, the recent development of Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) at the Stanford Synchrotron Radiation Lightsource (SSRL) now allows large paleontological and archaeological specimens to be non-destructively analyzed and imaged using major, minor, and trace element concentrations. Here we present high-resolution elemental maps covering entire specimens of Archaeopteryx (Thermopolis) and Confuciuornis, along with large sections of the enclosing matrix for Silica, Phosphorus, Sulfur, Chlorine, Calcium, Barium, Manganese, Iron, Zinc, Copper, Bromine, and Lead. As a complement to the elemental maps, spatially resolved point analyses provide quantitative results and have been used to convert mapped intensities to concentrations. Our results unequivocally show that the feathers in the Archaeopteryx are not simply impressions. Several rachises are clearly visible in maps of both phosphorous and sulfur; thus, indicating that feather chemistry has been partially preserved. Furthermore, zinc and copper levels in the bone are similar to concentrations in extant avian species. We therefore conclude that part of the original bone composition is preserved in these critical elements. The SRS-XRF scans of Confuciuornis show that trace metals, such as copper, are present in fossils as organometallic compounds most likely derived from original eumelanin. The distribution of these compounds provides a long-lived biomarker of melanin presence and density within a range of fossilized organisms. Metal zoning patterns may be preserved long after structural evidence (melanosomes) for color has been destroyed. Curation artefacts have also been resolved. Our results show SRS-XRF is a powerful new tool for the study of paleontological and archaeological samples.
It is fun to note that the meeting next week is full! There seems an awful lot of interest in this wonderful field of synchrotron-based imaging...as well there should be.