Multiattack

The diplodocus makes a stomp attack and a tail attack against two different targets.

Stomp

Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 21 (4d6 + 7) bludgeoning damage.

Tail

Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 17 (3d6 + 7) bludgeoning damage. If the target is a Large or smaller creature it is pushed 10 feet away from the diplodocus and knocked prone.