Thesis defence by Aude Cincotta

Soft tissues are non-biomineralized tissues that might, in specific cases, be preserved in geological records bearing important information on the biology of extinct organisms. This dissertation focuses on the study of the modes of preservation of fossil soft tissues such as feathers from different specimens of Ornithopoda, the clade including both dinosaurs and pterosaurs. The studied specimens include two small theropod dinosaurs from the Late Jurassic of Liaoning (China) and a neornithischian dinosaur from the Middle Jurassic of Siberia (Russia). A series of modern analytical techniques were used to study the ultrastructure of the soft tissues and to characterize their chemical composition. The thesis also presents palaeo-environmental reconstructions of two vertebrate-bearing localities in order to understand the fossilization modes of the fossils.

Photograph: Serikornis sungei, a four-winged paravian dinosaur from the Late Jurassic (about 160 millions years) of Jianchang (Liaoning, China) (from Lefèvre et al., 2017).