If it's a covered wagon in the Old West.... there are no roads. They went over the open plain. Therefore, no road kill.
I would imagine at some point there must have been a herd of buffao or horses passing by a wagon train, and a few of those animals must have run straight into the side of a wagon.
Thanks for bringing the topic back up pianowolfi.
I'll bet 'em lizards get dern near runnnnnned over *tips hat, spits cud*