Using light to describe the ancient world

Two spectroscopic techniques helped identify heme from a Tyrannosaurus rex bone

Fourteen years ago Mary Schweitzer and colleagues published a paper in PNAS with the title “Heme compounds in dinosaur trabecular bone”. This was a huge step forward in the study of ancient organic tissues. The paper described a meticulous study, and the abstract opened with “Six independent lines of evidence point to the existence of heme-containing compounds and/or hemoglobin breakdown products in extracts of trabecular tissues of the large theropod dinosaur Tyrannosaurus rex”. One of those techniques was Raman spectroscopy, and another was UV/Visible spectroscopy.

The UV-Vis spectra of tissue extracts exhibited a distinct band at around 405 nm, “…consistent with the absorbance characteristic of the Soret band of hemoglobin and other heme proteins…”. Likewise, Raman spectra of the tissue extract exhibited a set of “marker” bands in the 1300 to 1600 cm-1 region that could be linked to similar bands in modern day hemoglobin. Hence, both spectroscopic techniques were used to “fingerprint” hemoglobin from a 70 million year old fossil. Isn’t spectroscopy wonderful?

Schweitzer MH et al. 1997. Heme compounds in dinosaur trabecular bone. Proceedings of theNationalAcademyof Sciences of theUnited States of America. 94: 6291-6296.

Image compiled from Wikimedia Commons


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