Ryu Ryu no Mi, Model: Pteranodon in One Piece

As the fruit hasn't yet been shown in the anime, we don't know a lot about its appearance.

This devil fruit allows the user to turn into a Pteranodon, which is a large flight-capable predatory reptile. Once the user is transformed, they are able to fly at high speeds and cover large distances. They also have a significant boost to their overall physical abilities. When they are in their full form, they're way bigger than an average human. It also grants the user a very hard and durable Dragon-esque hide that gives them a strong defense.

As they can fly at high speed and are huge in size, they can violently push back and cause damage to whatever they fly at. The user's beak is long, sturdy, and sharp, which is an effective weapon which allows King to attack smaller objects and also tear apart things. The user also has the abilities of a Pteranodon, using their head as a slingshot at times to hunt their prey down. The wings are also a strong suit of this fruit and are able to generate strong winds and clash against swords too.

This devil fruit doesn't have weaknesses of its own other than the standard devil fruit weakness, that is the inability to swim.

King uses his devil fruit powers for combat, especially while fighting in the air with an aerial enemy. With the help of his flying ability, he can fly over large distances. He also has tremendous speed. When King is in his full form, he can fly into objects with immense speed and damage the enemy severely in the process. This can be seen when King dove right into Sanji while fighting him and rendered Sanji's suit's defenses useless. King claims that he can split his foes into half upon impact. King's head can also be used as a weapon.

When King is in his hybrid form, he uses his Pteranodon wing-arms like swords which allow him to release powerful air blades by swinging them. These slash attacks can greatly damage whatever they hit. For defense, King can use his durable wings as a shield and is also able to withstand powerful whirlwinds. King can also combine his transforming abilities with fire to shoot out multiple flame projectiles.

The techniques used by King are:

Tankyudon

In this technique, King flies towards his opponents in his hybrid form and when he gains a lot of momentum, he hits them with a sweeping strike of his Pteranodon wing.

Tempuraudon

In this technique, King is in his full form where he pulls back on his head crest with one arm and then stretches his face flat which causes his beak to retract into his face. He then lets go of his crest so that his head flings forward at extreme speed, like a slingshot, at his enemies with a massive force.

Barizodon

In this technique, King uses his Pteranodon wings like blades and launches a series of destructive elliptic air projectiles while flying.

Q. What does Ryu mean?

A. Ryu in Japanese refers to a ‘dragon’, which is a mythical creature.

Q. Who ate the Ryu Ryu no Mi, Model: Pteranodon?

A. King was the one who ate the Ryu Ryu no Mi, Model: Pteranodon.