Likely under body cladding. Cuts down drag and keeps out mud. Probably need to go to a dealer and replace the fasteners which likely came undone or failed. Most modern cars have stuff like this and it falls off easily. Had it happen to my car, it only cost $25 for a new piece.
Car shorts eh? Must have been going too fast and in a rut. Resulting drag heated the spandex up and got it brittle thusly shearing it off in the wind......