Good argument for these fossils coming from a catastrophe but not necessarily an argument that ALL fossils come from a catastrophe. It is troubling that science avoids catastrophic causes for past processes when even by my short time on earth that large sudden events do occur and have major impacts on environment.
If you leave a corpse of any living thing out for “gradual processes” to affect, it just rots, it doesn’t fossilize.
It would have to be suddenly buried under great amounts of pressure. A catastrophe.
It depends on how you want to define catastrophe. Fore example, a 500 year flood or massive landslide may be locally catastrophic, but events that take place on anything greater than a regional level are extremely rare. As far as “major impacts on the environment”, disturbance is what guides many processes, and while they may effect subpopulations or small regions, organisms and geomorphology are much more subject to long-term gradual change.