Article: Microstructural analysis of bone of the sauropod dinosaur Seismosaurus by transmission electron microscopy

Transmission electron microscopy (TEM) is commonly used to characterize materials with respect to crystal structure, chemical composition, defect density and type, as well as other microstructural features. Observation of bone from the Upper Jurassic sauropod dinosaur Seismosaurus using this technique, reveals a unique bimodal crystallite structure which appears to have local preferred orientation. Most crystallites are small oblong grains, averaging approximately 100 nm long and 20 nm wide; larger hexagonal crystallites are also present, ranging from 80 to 400 nm in diameter. The larger crystallites are found near naturally occurring canals and pores in the Seismosaurus bone. Electron diffraction and chemical analyses show that both the small and large crystallites are composed of fluorapatite. Comparative analyses of Seismosaurus with modern crocodile, Pleistocene mammoth, and Cretaceous theropod dinosaur bones show that younger fossil bone microstructure is essentially unaltered; the older fossil bones share a unique crystalline microstructure in which original and diagenetic apatite is intermixed.