Using light to describe the ancient world

Archive for May, 2011

#Recent News: A closer look

Microstructure of bone – Matthieu Lebon and colleagues present spectroscopic maps of diagenetic alteration at this fine scale

Imagine a world where you can analyse a fossil as you find it, learning what an ancient creature ate and what it’s world was like, all while sitting at its final resting place. As far fetched as that sounds, we are actually stepping closer and closer towards this point. An interesting step along this path was recently presented by Matthieu Lebon and colleagues in the Journal of Analytical Atomic Spectrometry. One of the battles with analysing a sample without first scrubbing it down is knowing where to sample, and understanding how samples change from place to place. Lebon and colleagues used Fourier Transform Infrared spectroscopy to produce fine scale chemical maps from the surfaces of fossil bones. One type of map shows the intensity of a spectral band attributed to carbonate normalised against phosphate, and hence reflects the distribution of carbonate: carbonate is a biological component of bone, but is also a near ubiquitous diagenetic gremlin that can potentially confound isotopic studies. Maps from a 15 thousand year old bone showed that carbonate had a close relationship with collagen, suggesting that the ion was an original, biogenic component. In contrast, maps from a 60 thousand year old bone showed that carbonate was centered in the most porous part of the bone, telling us that it had formed while that vile counterpart to diagenesis – groundwater – was flowing through the bone. The fine scale mapping approach may help us target the most immaculately preserved regions of fossil bone if we ever have the chance to sample on such a fine scale. Which, of course, is what our In-The-Field-Dinosaur-Analyser (ITFDA) will eventually be able to do.

Lebon M, Müller K, Bahain J-J, Fröhlich, Falguères C, Bertrand L, Sandt C, Reiche I. 2001. Imaging fossil bone alterations at the microscale by SR-FTIR microspectroscopy. Journal of Analytical Atomic Spectrometry 26: 922-929.

Image courtesy of the Department of Histology, Jagiellonian University Medical College, and sourced from Wikimedia Commons


NIR 2011

The 15th International Conference on Near Infrared Spectroscopy is being held in Cape Town this week. Yesterday I presented work from a forthcoming publication, where we used NIR to study burial history. Two other talks describing NIR of minerals were also presented, demonstrating just how powerful this spectroscopy could be for the paleosciences. Part of the reason that NIR has not attracted a lot of attention by the paleoscience community is that bands in the NIR region tend to come from light elements, which are not large components of bone mineral. There are plenty of light elements in secondary minerals though, which I think is where the focus should be. So, instead of studying bone mineral with NIR, we instead study burial history of bone from mineral composition. Given time, I think we will see some interesting fossil applications from NIR spectroscopy

E.T. Stathopoulou, V. Psycharis, G.D. Chryssikos, V. Gionis and G. Theodorou, “Bone diagenesis: new data from infrared spectroscopy and x-ray diffraction”, Palaeogeogr. Palaeocl. 266, 168 (2008). doi: 10.1016/j.palaeo.2008.03.022

Thomas, DB, McGoverin, CM, Chinsamy A. and Manley, M. 2011.Near infrared analysis of fossil bone from the Western Cape of South Africa. Journal of Near Infrared Spectroscopy. In press.

#News: Soft tissue preserved in a giant extinct marine lizard

Mosasaurs were lizards that patrolled Earth’s waterways during the end times of the dinosaurs. A new study from Johan Lindgren and colleagues has used infrared spectroscopy to show that soft tissues have been preserved in mosasaur bone.

Preservation of soft tissue in fossil bone is incredibly rare. So rare in fact, that reports of fossil soft tissues tend to attract a lot of flak, with the most common argument being that the ‘tissues’ are simply organic residues of fairly modern bacteria. This is why the very recent article from Johan Lindgren and colleagues is so fantastic: not only is protein shown to be preserved in mosasaur bone, but the authors also describe the titanic effort that went into ruling microbial contamination. And, of course, they used spectroscopy.

Infrared spectroscopy results are presented from analyses of a partly demineralised Prognathodon bone. The IR absorbance spectra show bands from the bone mineral – phosphate and carbonate stretches – as well as very clear bands due to organic material. These bands are also shown in a modern lizard bone, and in the spectrum of type 1 collagen. The spectra are also compared to analyses from microbes, which actually have very similar overall spectra. This is unsurprising, as the spectral bands are just informing about organic material, not collagen per se. ‘Fingerprinting’ for certain proteins (i.e. collagen) works by looking at the presence of certain bands, their positions, and their relative intensities – none of the microbes can truly mimic the Prognathodon protein spectrum. Head over to PLoS ONE for the exquisite details…

Lindgren, J., Uvdal, P., Engdahl, A., Lee, A.H., Alwmark, C., Bergquist, K.-E., Nilsson, E., Ekstro, P., Rasmussen, M.,Douglas, D.A., Polcyn, M.J., Jacobs, L.L. 2011. Microspectroscopic evidence of Cretaceous bone proteins. PLoS One 6(4): e19445. doi:10.1371/journal.pone.0019445

Image from Wikimedia Commons

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