Except for crocodiles, which animals would that be?Just look at what they have to defend themselves against as compared to wild horses.
african wild dogs
asian black bears
eurasian sabertoothed cats
possibly red dogs
And those predators mentioned for horses are only those, the horses met in todays Germany. In other parts of the world they met animals like jaguars (south america), dire wolfes (north america) or tigers (asia).