Quetzalcoatlus, Variant (5e Creature)
From D&D Wiki
huge beast, unaligned
Dive Attack. If the quetzalcoatlus is flying and dives at least 30 feet toward a target and then hits with a bite attack, the attack deals an extra 10 (3d6) damage to the target.
Flyby. The quetzalcoatlus doesn't provoke opportunity attacks when it flies out of an enemy's reach.
Bite. Melee Weapon Attack: +4 to hit, reach 10 ft., one target. Hit: 12 (3d6 + 2) piercing damage.
This giant relative of the pteranodon has a wingspan exceeding 30 feet. Although it can move on the ground like a quadruped, it is more comfortable in the air.