Young Spinosaurus

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

Reptilian Affinity. The spinosaurus never willingly attacks a reptilian Humanoid, such as a lizardfolk or dragonborn, unless attacked first. If magically forced to attack such a creature, the spinosaurus has disadvantage on attack rolls against it. This trait doesn't function if the spinosaurus's rider or tamer directs it to attack.

Multiattack. The spinosaurus makes one Bite attack and one Claw attack.

Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 24 (3d12 + 5) piercing damage. If the target is a Medium or smaller creature, it is grappled (escape DC 15). Until this grapple ends, the target is restrained, and the spinosaurus can't Bite another target.

Claw. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 15 (3d6 + 5) slashing damage.