The Crux of Discover Magazine publishes Jon Tennant’s report of the use of lasers on fossils, and how they can reveal the soft tissue chemistry of the original creature – and when a fossil has actually been assembled from several creatures:
When the team fired its laser at a Microraptor specimen, from the fossil graveyards of Liaoning, China, it lit up like a galaxy. What to the human eye appears as a rather mashed-up bird on a boring slab of rock, LSF transforms into a psychedelic horror show. Intriguingly, the skull of this particular specimen fluoresces in a way that suggests it could be a composite, with part of the skull added from another specimen.
A skull composite? The Microraptor skull under white light, top, shows subtle color differences. Under laser-light stimulation, the bone fluoresces from differences in fossil mineralogy. (Credit: http://dx.doi.org/10.1371/journal.pone.0125923.g013)
(Verbatim from The Crux)“Tom [Kaye] and I have laser-imaged thousands of dinosaur fossils and, aside from revealing soft tissue and bone details that were previously ‘invisible’ or unclear, it has helped us to identify potential composite specimens,” says [Mike] Pittman. “In these specimens, we see specific bones or slabs that have fluorescence colors that are amiss from the rest of the specimen. We can then explore further using other instruments (e.g. CT scanning) to confirm if it has been compiled from the parts of several specimens.”
In all fairness, I have used fraud in a slightly unfair manner. Not all fossils are embedded in rock, and even those that are quite often come from disarticulated skeletons; assemblage must be a bit of a guessing game if they come from a bone bed (i.e., area where more than one carcass was located). On the other hand, there have been documented cases of fraud, often by locals who find the fossils and assemble them in such a way as to intrigue fossil hunters – and induce them to pay more.
And it’s a great picture.
Going to the original article at PLOS ONE, I found this interesting discussion of one specimen:
Figure 6 from the article. “Unidentified Liaoning fossil specimen.
An unidentifiable specimen from a Liaoning rock slab containing a Microraptor specimen (LVH 0026). No diagnostic bones are visible on the specimen surface, but laser penetration into the matrix induced fluorescence in multiple teeth and scales, making the identification of a fish possible. Scale bar 1 cm. http://dx.doi.org/10.1371/journal.pone.0125923.g006″A very small specimen (Fig 6) was discovered on the same slab as a Microraptor specimen (Theropoda: Dromaeosauridae [20]) discovered in Liaoning province, China (LVH 0026). The visible bones were not sufficient to identify the specimen, so it was submitted for laser analysis as a last resort. Laser fluorescence identified the specimen as a fish within minutes. In this case the hydroxyapatite in the bones and teeth fluoresced at a higher intensity than the surrounding matrix. The higher intensity fluorescent reaction of the specimen, in comparison to the matrix, revealed teeth below the surface and transparent scales on the surface that were virtually invisible in reflected light (Fig 7). Note that the bone fragment on the right in Fig 7 actually lies under the scale. Laser fluorescence of the formerly translucent scale shows enough detail to count the scale’s growth rings.
Figure 7. From the article. ” Details enhanced with laser fluorescence.
A, White light photo. B, Fluoresced with a 457 nm blue laser. Fish scale on the surface is translucent and barely perceivable under white light. Growth rings on the scale are revealed under fluorescence and can be counted. Bone fragments are brought out in sharp detail. Arrows point to teeth in the matrix. Scale bar 0.5 mm. http://dx.doi.org/10.1371/journal.pone.0125923.g007″
The article notes that the laser can penetrate slightly into the matrix, revealing buried fossils and fossil fragments. Fascinating!
