|Wisent with aurochs-like horns at Hellabrunn Zoo, Munich|
An interesting question is if hybridization with bison might have also left a track in the aurochs. There is one detail that makes me consider it not unlikely: the curly hair on the forehead and sometimes also neck and face that we see in many European taurine bulls (and cows, but to a lesser extent). Cattle outside of Europe, especially zebuine cattle, always lack this trait. Perhaps it is a trait that found its way into the gene pool of B. p. primigenius by occasional hybridization with bison and got fixed by sexual selection. But that is only an idea of mine.