Whether scientists have directly observed animals being killed by a sandslide in the Gobi doesn’t bear on whether a sandslide could have killed animals in the Gobi desert 65 million years ago. As long as sandslides can kill animals, the authors’ theory can be supported by other evidence. No one needs to directly witness a death due to sandslide in order for such a death to be a reasonably possible occurrence.

The current state of the site doesn’t impact whether the site could have been a stable dune 65 million years ago.

We already know that no fossils were found in the second type of standstone at Ukhaa Tolgod. So whether fossils have been found in that kind of stone at different sites has no impact. The argument is about Ukhaa Tolgod.

The argument is about what happened 65 million years ago. The fact sandslides haven’t occurred in 5 million years doesn’t relate to whether they could have occurred 65 million years ago.

This weakens by providing an alternate explanation for how the fossils can be found in the third type of sandstone. Remember, the author jumped to sandslides as the explanation merely because the third type of sandstone “exhibits a structure similar to that caused by” sandslides. But if other natural processes can produce the third type of sandstone, then that raises the possibility another natural process besides a sandslide occurred to make the sandstone have the structure it does. We don’t need to jump to the sandslide hypothesis.