Maybe if you reduced the temps to single degree Kelvin levels, otherwise the soft tissue should disappeared due to simple thermal degradation over 65 million years.
I can see an “out” for them... maybe.
The earth is billions of years old,
but somehow, some dinosaurs continued to live up to a few thousand years ago.
Soft tissue, made of protein, does no undergo thermal degradation at 13C, which is what the typical soil temperature is near the surface, where the fossils end up. All natural protein decay you see in your kitchen is done by bacteria and fungi. To degrade protein thermally you normally have to go past water boiling point; in other words, cook it. Cooked meat is the natural result of this degradation. To cook a fossil, it would have to be buried something like a kilometer deep, where no paleontologist would ever find it.