Synthetic fossils are chemically comparable to real fossils:
Feathers undergoing high heat, high pressure experiments in sediment to simulate fossilization are chemically comparable to fossil feathers. Both consistent of dark stains produced by surviving, altered melanin pigment.
Preprint: Research Square
By compacting modern tissues in sediment and then ‘pressure cooking’ them to simulate long-term burial during fossilization, one can produce samples that are macro- and microscopically comparable to organically preserved fossils down to the level of an electron microscope.
Feathers do not clump together during compaction:
Contrary to earlier experiments using a simple press, when sub-aqueously buried before compaction, feathers on bird carcasses do not appear to significantly clump together. Feathers in compression fossils can be interpreted without mistaking them for more primitive structures due to compaction.
Dinosaur blood? Self-organizing structures:
Claims of dinosaur blood cells are challenged by experiments examining microbial decay and thermal degradation of bird and reptile skin structures. Turkey scales and associated skin that were partially degraded inadvertently produced the same range of folded structures as seen in the dinosaur fossil when examined under the vacuum of an electron microscope. The dinosaur structures are possibly degraded, folded organic material from infiltrating microbes rather than original organics, let alone preserved blood cell structures.
My summary: The Conversation
Keratin protein does not fossilize:
Feathers placed through high pressure, high temperature ‘artificial maturation’ to simulate deep burial and geothermal heat over millions of years degrade into a thick, smelly fluid that is water soluble at elevated temperature and not found in fossils. Other components of keratinous structures, such as pigments or calcium phosphates, can persist while proteins are lost from the fossils.