The Bull .. well I guess sometime, but I'm thinking more prehistoric animal - elasmothere, eohippus, chalicothere, or something of that nature.
This uses MM2, not savage species, rules on skill points and feats.
Here's the Chalicothere :
Chalicothere
Large Animal
Hit Dice: 6d8+12 (39hp)
Initiative: +4 (+0 Dex, +4 Improved Initiative)
Speed:10ft. ( 20ft. shambling)
AC: 13 (-1 size,+0 Dex, +4 natural), touch 9, flat-footed 13
Attacks: Claw swipe +6 (+4 Base, +3 Str, -1 size)
Damage: Claw swipe 1d8+3/20/x1 and knockdown
Face/Reach: 5 ft. by 5 ft./10 ft.
Special Attacks: Knockdown
Special Qualities : Low - Light Vision
Saves: Fort +7, Ref +5, Will +0
Abilities: Str 17, Dex 11, Con 15, Int 1, Wis 6, Cha 9
Skills: Spot +6, Listen +6
Feats: -
Climate/Terrain: Warm forest and plains
Organization: Solitary, pair, or herd
(3- 6)
Challenge Rating: 3
Treasure: None
Alignment: Always neutral
Advancement: 4 - 7 HD (Large), 8 - 9 HD (Huge)
A chalicothere is a large creature resembling a cross between a forest sloth and a horse. It has a horselike head, and its forelimbs are tipped with large claws. The creature is stupid and slow-moving.
COMBAT
Chalicotheres attack only if their lives are threatened or their territories are invaded. If defending its territory, 5 pounds of fresh plant matter thrown to a chalicothere has a 50% chance of distracting it.
The chalicothere can use its knuckles to move at a rate of 20 ft., but cannot attack in any such round.
Knockdown (Ex): If a chalicothere scores a critical hit, it does not deal multiple damage due to its rather blunt claws; it simply knocks a victim of one or more sizes smaller than itself down. Knocked down victims must spend a move-equivalent action standing up.