Gigantosaurus (CR 13)

Gargantuan Animal
Alignment: Always neutral
Initiative: +1 (Dex); Senses: keen scent, low-light vision, Listen +15, and Spot +16

AC: 15 (-4 size, +1 Dex, +8 natural) touch 7, flat-footed 14
Hit Dice: 24d8+204 (312 hp)
Fort +22, Ref +15, Will +10
Speed: 40 ft.
Space: 20 ft./20 ft.
Base Attack +18; Grapple +44
Attack: Bite +28 melee
Full Attack: Bite +28 melee and 2 claws +23 melee
Damage: Bite 4d6+21/19-20/x3, claw 1d8+10
Special Attacks/Actions: Improved grab, pinning, swallow whole, wounding bite
Abilities: Str 38, Dex 12, Con 26, Int 2, Wis 14, Cha 10
Special Qualities:
Feats: Alertness; Improved Critical (bite); Improved Natural Attack (bite); Run; Toughness (4); Track
Skills: Listen +15 and Spot +16
Advancement: 25-36 (Gargantuan), 37-72
Climate/Terrain: Warm plains
Organization: Solitary, pair, or group (3-6)
Treasure/Possessions: None

Source: Dragon #318

Improved Grab (Ex): To use this ability, a gigantosaurus must hit an opponent at least one size smaller with its bite attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity, If it wins the grapple check, It establishes a hold and can try to swallow or pin the foe the following round.

Pinning (Ex): A gigantosaurus can pin a grabbed opponent of up to two sizes smaller than itself to the ground with one of its feet by making a successful grapple check.

The pinned creature takes 2d6+21 points of bludgeoning damage per round and cannot move as long as the pin persists. The gigantosaurus gains a +4 circumstance bonus on attack rolls to hit a pinned target with its bite. A gigantosaurus can pin one creature at a time.

Swallow Whole (Ex): A gigantosaurus can try to swallow a grabbed opponent of up to two sizes smaller by making a successful grapple check.

The swallowed creature takes 2d8+8 points of bludgeoning damage and 8 points of acid damage per round from the gigantosaurus's gizzard. A swallowed creature can cut its way out by using a light slashing or piercing weapon to deal 35 points of damage to the gizzard (AC 14). Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out.

A gargantuan gigantosaurus's immense gizzard can hold 2 Large, 8 Medium, 32 Small, or 128 Tiny or smaller opponents.

Wounding Bite (Ex): A gigantosaurus's teeth are razor-sharp and slice through flesh with shocking ease. Its bite naturally threatens a critical hit on a 19-20 and inflicts triple damage on a successful critical hit. In addition, a creature critically hit by a gigantosaurus's bite takes 2 points of Constitution damage from the terrible nature of the wound.

Keen Scent (Ex): A gigantosaurus can detect creatures by scent in a 180-foot radius.

Gigantosauruses often hunt in pairs or small groups and use cunning tactics.

A favored tactic finds one or two gigantosauruses charging into the midst of their chosen prey and flushing them toward the others who lurk at the edge of a nearby forest in ambush. Against single targets, a gigantosaurus uses its formidable special attacks to grab, pin, and swallow victims with shocking speed.