Protoceratops (CR 3)

Medium Animal
Alignment: Always neutral
Initiative: +0; Senses: low-light vision, scent, Listen +5, and Spot +5

AC: 18 (+8 natural), touch 10, flat-footed 18
Hit Dice: 5d8+20 (42 hp)
Fort +8, Ref +4, Will +2
Speed: 30 ft.
Space: 5 ft./5 ft.
Base Attack +3; Grapple +6
Attack: Bite +6 melee
Full Attack: Bite +6 melee
Damage: Bite 1d8+4
Special Attacks/Actions: Powerful charge
Abilities: Str 16, Dex 11, Con 19, Int 1, Wis 12, Cha 6
Special Qualities:
Feats: Alertness; Endurance
Skills: Listen +5, Spot +5, and Survival +9
Advancement: 6-10 HD (Medium); 11-15 HD (Large)
Climate/Terrain: Warm deserts
Organization: Solitary, pair, or herd (4-7)
Treasure/Possessions: None

Source: Sandstorm

Powerful Charge (Ex): A protoceratops deals 2d8+11 points of damage when it makes a charge.

Skills: Protoceratops have a +4 racial bonus on Survival checks.

Protoceratops are not very aggressive, but because they are the favored prey of larger creatures, they have developed effective defenses. A threatened protoceratops lowers its head and charges, attempting to bull rush an enemy and escape. If it cannot get away, it attempts to charge as often as possible.