Evidence of preserved collagen in an Early Jurassic sauropodomorph dinosaur revealed by synchrotron FTIR microspectroscopy.

Fossilized organic remains are important sources of information because they provide a unique form of biological and evolutionary information, and have the long-term potential for genomic explorations. Here we report evidence of protein preservation in a terrestrial vertebrate found inside the vascular canals of a rib of a 195-million-year-old sauropodomorph dinosaur, where blood vessels and nerves would normally have been present in the living organism. The in situ synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectra exhibit the characteristic infrared absorption bands for amide A and B, amide I, II and III of collagen. Aggregated haematite particles (α-Fe2O3) about 6∼8 µm in diameter are also identified inside the vascular canals using confocal Raman microscopy, where the organic remains were preserved. We propose that these particles likely had a crucial role in the preservation of the proteins, and may be remnants partially contributed from haemoglobin and other iron-rich proteins from the original blood.

Dietary adaptions in the ultrastructure of dinosaur dentine.

Teeth are key to understanding the feeding ecology of both extant and extinct vertebrates. Recent studies have highlighted the previously unrecognized complexity of dinosaur dentitions and how specific tooth tissues and tooth shapes differ between taxa with different diets. However, it is unknown how the ultrastructure of these tooth tissues contributes to the differences in feeding style between taxa. In this study, we use third harmonic generation microscopy and scanning electron microscopy to examine the ultrastructure of the dentine in herbivorous and carnivorous dinosaurs to understand how the structure of this tissue contributes to the overall utility of the tooth. Morphometric analyses of dentinal tubule diameter, density and branching rates reveal a strong signal for dietary preferences, with herbivorous saurischian and ornithischian dinosaurs consistently having higher dentinal tubule density than their carnivorous relatives. We hypothesize that this relates to the hardness of the dentine, where herbivorous taxa have dentine that is more resistant to breakage and wear at the dentine-enamel junction than carnivorous taxa. This study advocates the detailed study of dentine and the use of advanced microscopy techniques to understand the evolution of dentition and feeding ecology in extinct vertebrates.

Third-harmonic generation microscopy reveals dental anatomy in ancient fossils.

Fossil teeth are primary tools in the study of vertebrate evolution, but standard imaging modalities have not been capable of providing high-quality images in dentin, the main component of teeth, owing to small refractive index differences in the fossilized dentin. Our first attempt to use third-harmonic generation (THG) microscopy in fossil teeth has yielded significant submicrometer level anatomy, with an unexpectedly strong signal contrasting fossilized tubules from the surrounding dentin. Comparison between fossilized and extant teeth of crocodilians reveals a consistent evolutionary signature through time, indicating the great significance of THG microscopy in the evolutionary studies of dental anatomy in fossil teeth.

Embryology of Early Jurassic dinosaur from China with evidence of preserved organic remains.

Fossil dinosaur embryos are surprisingly rare, being almost entirely restricted to Upper Cretaceous strata that record the late stages of non-avian dinosaur evolution. Notable exceptions are the oldest known embryos from the Early Jurassic South African sauropodomorph Massospondylus and Late Jurassic embryos of a theropod from Portugal. The fact that dinosaur embryos are rare and typically enclosed in eggshells limits their availability for tissue and cellular level investigations of development. Consequently, little is known about growth patterns in dinosaur embryos, even though post-hatching ontogeny has been studied in several taxa. Here we report the discovery of an embryonic dinosaur bone bed from the Lower Jurassic of China, the oldest such occurrence in the fossil record. The embryos are similar in geological age to those of Massospondylus and are also assignable to a sauropodomorph dinosaur, probably Lufengosaurus. The preservation of numerous disarticulated skeletal elements and eggshells in this monotaxic bone bed, representing different stages of incubation and therefore derived from different nests, provides opportunities for new investigations of dinosaur embryology in a clade noted for gigantism. For example, comparisons among embryonic femora of different sizes and developmental stages reveal a consistently rapid rate of growth throughout development, possibly indicating that short incubation times were characteristic of sauropodomorphs. In addition, asymmetric radial growth of the femoral shaft and rapid expansion of the fourth trochanter suggest that embryonic muscle activation played an important role in the pre-hatching ontogeny of these dinosaurs. This discovery also provides the oldest evidence of in situ preservation of complex organic remains in a terrestrial vertebrate.