In the Cretaceous mud we found a shattered dinosaur thigh by following fragments of petrified bone scattered down an arroyo.

But—I think I’ve explained this before—if you find a tiny piece, how can you tell whether it’s a dissolving dinosaur?

Lick it. If it’s bone, rather than some other stone like agate or silicified wood, the porous vesicles left by once-living cells and capillaries will wick up the moisture of your tongue, and it will stick.