BlueCrab and Neil_Boekend did. Ms. Frizzle has pushed BraveBean's corpse into the grave and is covering it with soil. Cuegan are collecting more stones for the cairn.
… the raptor?
Spoiler:
It's about to land on the stone with BraveBean's Beanie. (It sees Ms. Frizzle digging, so it hopes to find some worms.)