Aurochs

Oracle Text

Trample

Whenever Aurochs attacks, it gets +1/+0 until end of turn for each other attacking Aurochs.

Card Rulings

10/4/2004 The bonus is not applied until after you check for attack legality, so it is a 2/3 creature when declaring attackers.
10/1/2009 The ability counts the number of attacking creatures with the creature type Aurochs, not just those named Aurochs.