Ancient birds were feeding, not breeding:
Structures in the abdomen of Mesozoic birds interpreted as preserved ovaries are unlikely to be so, given their little preservation potential. Instead, they match plant propagules found in the same fossil beds – indicating that these were stomach contents.
Study: Mayr et al. 2020. Scientific Reports
Shuvuuia feathers are inorganic:
Fibers around the dinosaur are calcium phosphate, not organic keratin protein as suggested by antibody studies. Antibodies possibly adhered to glue on the fibers applied during excavation or preparation. The preserved salts are used to harden keratin in life and could indicate that the feathers were more complex, branching structures, rather than simple strands.
Study: Saitta et al. 2018. Organic Geochemistry
Media: Briefly mentioned in National Geographic
Fossils with soft tissues are not always rotten:
Fossilization involves a complex interplay of multiple factors, beyond just microbial decay. In fact, some preserve soft tissues because such decay was limited in their burial environment. This understanding influences our ability to properly interpret fossils to study evolution.
Study: Parry et al. 2017. BioEssays
Evan T. Saitta, Ph.D. 