Frivolous ASB thread

  I think that would cause ecological chaos.  Even assuming the impossible physics of the case, including how much fuel they would need and how they avoid boiling themselves alive or breaking every bone in their bodies at that speed.  They would be virtually impossible to catch other than when asleep or feeding so are likely to bred in massive numbers unless in some way predators evolve to counter them.  Also it would make them virtually impossible for humans to catch or train, even if the immunity to traveling at supersonic speed carried over to a rider from the horse.  [If it did some nomadic tribe that learnt to tame horses would probably establish something approaching a world empire].  Without any appreciable number of horses for cavalry or as beasts of burden human history would be drastically different.  The great plains would probably be settled by sedentary people earlier and such states would last longer without nomadic warriors periodically sweeping in from the steppes to raid and loot.