Glyptodon (CR 5)

Large Animal
Alignment: Always neutral
Initiative: -1 (Dex); Senses: low-light vision, Listen +8, and Spot +8

AC: 18 (-1 size, -1 Dex, +10 natural), touch 8, flat-footed 18
Hit Dice: 10d8+33 (72 hp); DR: 5/piercing
Fort +10, Ref +6, Will +8
Speed: 20 ft., burrow 5 ft.
Space: 10 ft./5 ft.
Base Attack +7; Grapple +16
Attack: Tail +11 melee
Full Attack: Tail +11 melee and bite +6 melee
Damage: Tail 2d6+5/3, bite 1d4+2
Special Attacks/Actions: Augmented critical, trample
Abilities: Str 20, Dex 8, Con 17, Int 2, Wis 12, Cha 7
Special Qualities:
Feats: Alertness; Improved Natural Attack (rail); Power Attack; Toughness
Skills: Listen +8, Spot +8, and Swim +8
Advancement: 11-15 HD (Large); 16-30 HD (Huge)
Climate/Terrain: Cold plains
Organization: Solitary, pair, colony (3-4), or herd (6-20)
Treasure/Possessions: None

Source: Frostburn

Augmented Critical (Ex): A glyptodon deals triple damage if it scores a critical hit with its tail attack.

Trample (Ex): As a full-round action, a glyptodon can move up to twice its speed and literally run over Medium or smaller creatures. This attack deals 1d6+7 points of damage. Trampled opponents can make attacks of opportunity against the glyptodon at a -4 penalty. If they do not make attacks of opportunity, trampled opponents can attempt a DC 20 Reflex save for half damage. The save DC is Strength-based.

A glyptodon found by itself is common, but the creatures also fight in small groups, circling around the young to create a wall of armored flesh. If provoked, a glyptodon typically begins a combat by attempting to trample its foe.