All the theories about fossilization and "hydrologic sorting" of the bones to explain their appearance post-flood posit very hot and very turbulent water conditions. The amount of water required to hold the amount of salt left behind at Bonneville would require a water column that could not possibly be contained by the surrounding geography.
Is it possible the local surrounding geography at Bonneville was still undergoing a relatively late change? How do we know what geography was still in the precess of sinking or rising?
We don't know all the dynamics of the preservation of fossilization, obviously -- but they sure ain't 60 million year old bones as "science" has sworn. Or even 1 million year old bones.