Adult Spinosaurus

Keen Hearing and Smell. The spinosaurus has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Hold Breath. The spinosaurus can hold its breath for 1 hour.

Stunning Dive. If the spinosaurus swims at least 20ft., towards a target and then hits it with a bite attack on the same turn, if the target is a creature, it must succeed a DC 16 Strength saving throw or be grappled underwater until the end of the spinosaurus turn on a failed save.

Sail Distraction. As a bonus action, the spinosaurus  can lower its head close to the ground, presenting the sail on its back to attackers. While making its sail distraction, the spinosaurus has disadvantage on attack rolls made to attack with its tail and those attacking the spinosaurus have disadvantage on their attack rolls.

Multiattack. The spinosaurus makes two attacks: one with its bite and one with its claw.

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 33 (4d12 + 7) piercing damage. If the target is a Medium or smaller creature, it is grappled (escape DC 16). Until this grapple ends, the target is restrained, and the spinosaurus can't bite another target.

Claw. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 20 (3d8 + 7) slashing damage.

Tail. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 20 (3d8 + 7) bludgeoning damage.