You are absolutely right that a worldwide flood would account for these fossils very well. And what is the evidence for a worldwide flood that another commenter asks for? Billions of dead things (fossils) buried in rock layers laid down by water all over the earth. And that is exactly what we find. Sedimentary rock covers about three quarters of the earth’s surface and many of these contain fossils. We find marine fossils even on the top of Mount Everest, which means that the mountain must have been pushed up through tectonic plate activity during and after a massive flood.
Further, slow burial as a previous poster assumes, doesn’t work for fossilization, especially for organisms with soft bodies. Fossilization requires rapid and generally deep burial as the article acknowledges. Oxygen must be quickly excluded as must scavengerswithin days at most. Gradual burial just doesn’t work.
I am not sure how the narrative of a global ice age causing extinction fits in either. There is really no good evidence for a worldwide ice age or ages“snowball earth”. That postulate creates a lot more problems than it solves. The striations on the rocks which are interpreted as evidence for ice ages in the lower latitudes were most likely created by massive catastrophic landslides, most of them in a submarine environment.
There are lots of speculative theories to explain an ice age, but these fall far short of being reasonable. The only reasonable explanation is I have read is from Michael Oard. Like fossilization, ice ages take very special conditionsFirst, warmer oceans are necessary to put massive amounts of moisture in the air. Perhaps you’ve heard the phrase, “It’s too cold to snow.” That is because really cold air doesn’t carry enough moisture for snow. Next, for glaciers to form you need many years of accumulated snowfall. Much cooler continents are necessary so that the moisture comes down as snow and remains un-melted through the summer. How could both of these requirements be met? The oceans would be warmed by massive global techtonics and volcanism; the land masses would remain cool due to the massive amounts of volcanic dust in the atmosphere.
Another problem with this published narrative is that it states that half the species uncovered are unknown. That is often an argument from ignorance. Dr. Carl Werner conducted a multi-year study and found that many of the purported new species are not really such if fossils from museums around the world are actually comparedand on many occasions, the fossils are very similar to existing, living species.