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Survival of T. rex Microvascular Structures from Deep Time

Using techniques available at the Advanced Light Source (ALS), researchers led by Elizabeth Boatman, formerly at UC Berkeley and now at UW-Stout, demonstrated how soft-tissue structures may be preserved in dinosaur bones, countering long-standing scientific dogma that protein-based body parts cannot survive more than one million years.

A sample from a 66-million-year-old Tyrannosaurus rex tibia provided evidence that vertebrate blood vessels—predominantly composed of collagen and elastin, which don’t fossilize the same way as mineral-based bone—may persist across geologic “deep time” through two natural, protein-fusing (“cross-linking”) processes: Fenton chemistry and glycation.

Boatman used small-angle x-ray scattering (SAXS) at Beamline 7.3.3 to help establish that the specimen is indeed the animal’s original collagen-based tissue because the vessel structures possessed periodic features consistent with modern collagen fibers. To understand how this collagen-based tissue is preserved, the team conducted further investigations. 

Using x-ray fluorescence (XRF) mapping, iron K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and x-ray diffraction (XRD) at Beamline 10.3.2, the team discovered the presence of finely crystalline goethite (α-FeOOH), a known product of cross-linking processes. 

Simultaneously, modern tissues treated with the proposed cross-linking mechanisms were compared to the dinosaur vessels using Fourier-transform infrared spectromicroscopy (FTIR) at Beamlines 1.4 and 5.4. By revealing protein-folding patterns, FTIR indicated that both cross-linking mechanisms have occurred.

The team concluded that Fenton chemistry and glycation likely contributed to collagen preservation in the dinosaur vessels. These cross-linking reactions, combined with the protection offered by the dense mineral of the dinosaur’s large tibia bone, begin to explain how original soft tissues persist.

Photo of a T. rex skeleton, posed mid-attack on a triceratops skeleton, on black background; inset shows visible-light microscopy image of T. rex vascular structure.
In order to take these mesmerizing microscopy images (inset), the team carefully demineralized small bits of T. rex bone to liberate the preserved vessel tissue inside. The sample used in this study came from the famous, nearly complete fossil specimen known as “the Nation’s T. rex,” which is currently on display at the Smithsonian National Museum of Natural History. (Credit: Boatman et al. and Smithsonian Institute)

E.M. Boatman, M.B. Goodwin, H.-Y.N. Holman, S. Fakra, W. Zheng, R. Gronsky, and M.H. Schweitzer, “Mechanisms of soft tissue and protein preservation in Tyrannosaurus rex,” Sci. Rep. 9, 15678 (2019), doi: 10.1038/s41598-019-51680-1.

Adapted from the Berkeley Lab Science Snapshot, “Berkeley Lab Helps Reveal How Dinosaur Blood Vessels Can Preserve Through the Ages.”