Mauricio Barbi, Phil R. Bell, Federico Fanti, James J. Dynes, Anezka Kolaceke, Josef Buttigieg & Philip J. Currie (2019)
Integumentary structure and composition in an exceptionally well-preserved hadrosaur (Dinosauria: Ornithischia).Â
PeerJ Preprints 7:e27698v1
Preserved labile tissues (e.g. skin, muscle) in the fossil record of terrestrial vertebrates are increasingly becoming recognized as an important source of biological and taphonomic information. Here, we combine a variety of synchrotron radiation techniques with scanning electron and optical microscopes to elucidate the structure of 72 million-year-old squamous (scaly) skin associated with a hadrosaurid dinosaur from the Late Cretaceous of Alberta, Canada. Scanning electron and optical microscopy independently reveal that the three-dimensionally preserved scales are associated with a band of carbon-rich layers up to a total thickness of 75 Îm. Compositionally, this band deviates from that of the surrounding matrix; Fourier-transform infrared spectroscopy and soft X-ray spectromicroscopy analyses indicate the presence of carboxylic compounds. The regions corresponding to the integumentary layers are distinctively enriched in iron compared to the associated sedimentary matrix and seem associated to kaolinite. These carbonyl-rich layers are apparently composed of subcircular bodies resembling preserved cell structures. Each of these structures is encapsulated by calcite/vaterite, with iron predominantly concentrated at its center. The presence of iron, calcite/vaterite and kaolinite might have played important roles in the preservation of the layered structures.