Anatotitan (CR 7)

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

AC: 15 (-2 size, -1 Dex, +8 natural), touch 7, flat-footed 15
Hit Dice: 12d8+90 (144 hp)
Fort +15, Ref +7, Will +5
Speed: 30 ft.
Space: 15 ft./10 ft.
Base Attack +9; Grapple +25
Attack: Tail slam +15 melee
Full Attack: Tail slam +15 melee
Damage: Tail slam 1d6+12
Special Attacks/Actions: Trample 2d10+12
Abilities: Str 26, Dex 9, Con 24, Int 1, Wis 12, Cha 7
Special Qualities:
Feats: Alertness, Endurance, Run, Toughness (x2)
Skills: Listen +8, Spot +8, and Swim +13
Advancement: 13-24 HD (Huge), 25-36 HD (Gargantuan)
Climate/Terrain: Temperate and cold plains
Organization: Solitary, pair or herd (6-36)
Treasure/Possessions: None

Source: Converted

Trample (Ex): An anatotitan can literally run over any creatures in its way that are of Large or smaller size. Creatures trampled must make a Reflex save (DC 24 half) or take 2d10+12 damage. The save DC is Strength-based.

Anatotitans avoid combat whenever possible, preferring to flee from confrontation. If their young are threatened, however, they fight with their powerful tails. An anatotitan will only make a trample attack as part of an escape attempt, or if pursuers are too vigilant.

Originally found in the first edition Monster Manual (1977, Gary Gygax), Monstrous Compendium MC3 - Forgotten Realms Appendix I (1989), and Monstrous Compendium Annual Two (1995).