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(Dinosaur) Mamenchisaurus

By ДиБгд, CC BY-SA 3.0,, Mamenchisaurus
By ДиБгд, CC BY-SA 3.0,

This massive quadruped has a long tail, a box-like head attached to a disproportionately long neck, and a wrinkled, elephantine hide.

Originally Posted by Shade of the En World forums.
On this Thread

Although mamenchisaurs are not the longest, heaviest or otherwise record-setting dimensionally of the massive sauropods, they do have the longest necks of their family. The neck of a mamenchisaurus takes up almost 40 feet of its 70 foot length and is held at a slightly erect angle. Due to the massive pressures needed to pump blood up to its head, multiple heart-like structures are positioned along its neck. Mamenchisaurs are at a significant advantage when it comes to a wide field of vision and a selection of food from the tallest of trees, but their lives are among the shortest of the sauropods (only seventy-five years at a maximum, barring a violent end) due to their fragile hearts.

Dinosaur, Mamenchisaurus
Colossal animal
Hit Dice22d8+181 (277 hp)
Speed30 ft. (6 squares)
Armor Class12 (-8 size, +1 Dexterity, +9 natural), touch 3, flat-footed 11
Base Attack/Grapple+16/+42
AttackTail slam +18 melee (4d6+15 plus thunderous snap)
Full AttackTail slam +18 melee (4d6+15 plus thunderous snap)
Space/Reach50 ft./40 ft.
Special AttacksThunderous snap, trample 8d8+15
Special QualitiesLow-Light Vision, Scent
SavesFort +22, Ref +16, Will +11
AbilitiesStrength 30, Dexterity 12, Constitution 25, Intelligence 1, Wisdom 14, Charisma 10
SkillsListen +12, Spot +21
FeatsAlertness, Diehard, Endurance, Epic Toughness, Great Fortitude, Iron Will, lightning reflexes, Power Attack
EnvironmentWarm forests, plains and hills
OrganizationSolitary, pair or herd (10-24)
Challenge Rating10
AlignmentAlways neutral
Advancement23-66 HD (Colossal)
Level Advancement


Although they are more closely related to camarasaurs and brachiosaurs than diplodocids, they bear the latter’s whip-like tail, complete with its sonic consequences. More often then not, however, they merely trod on any threat to their safety.

Thunderous Snap (Ex): Although they are ponderous, a mamenchisaurus’ whip-like tail can move faster than sound. Any creature struck by a mamenchisaurus’ tail slam must make a Fortitude save (DC 28) or be stunned for 1d4 rounds and deafened for 1d4 minutes. On a successful save, the creature is merely deafened for 1d4 minutes. The save DC is Constitution-based.

Trample (Ex): A mamenchisaurus can literally run over any creatures in its way that are of Gargantuan or smaller size. Creatures trampled must make a Reflex save (DC 31 half) or take 8d8+15 damage. The save DC is Strength-based.

Originally appeared in Monstrous Compendium Volume Three: Forgotten Realms Appendix (1989).

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