Flyby. The ornithocheirus doesn’t provoke an opportunity attack when it flies out of an enemy’s reach. 

Infected. The Ornithocheirus can infect a dinosaurs and prehistoric marine and flying reptiles with the plaque and turn that dinosaur into a zombie

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 6 (2d4 + 1) piercing damage.

Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 15 (2d6 + 8) slashing damage.

Multiattack. The Ornithocheirus can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Undead Nature. A zombie Ornithocheirus doesn't require air, food, drink, or sleep.