Ryū (竜,Ryū?) is Japanese for "dragon" and can be found in the Japanese term for "dinosaur" (恐竜,kyōryū?).
Strengths and Weaknesses
This fruit bestows the power to turn into a spinosaurus, a large and powerful, semiaquatic predator from the prehistoric era, as well as a hybrid between a spinosaurus and human (or other) at will.
As with other dinosaur-based Zoan types, transforming into a spinosaurus grants the user tremendous strength, particularly in their jaw, tail, and arms (in hybrid form). In his full-beast form, Page One is able to smash and tear apart buildings with ease using his maw and tail. In his hybrid form, he is strong enough to send a Raid Suit-donning Sanji flying and crashing through several buildings with a single swipe of his arm.
Being a dinosaur Zoan, this fruit bestows much greater durability than standard Zoan types do. When Monkey D. Luffy's Elephant Gun hit Page One's lower jaw, the latter claimed that his jaw had "loosened up a little".
No weaknesses are currently known aside from the standard Devil Fruit weaknesses.
Page One uses this fruit to great effect during combat and when going on the offensive, starting a destructive rampage in order to lure out Sanji.
Page One without his eyebrow horns.
Page One's tail as shown during his first appearance.
Page One's new tail.
After a new fossil discovery (as of April 2020) suggested that the ancient Spinosaurus's tail was more akin to a paddle to allegedly aid the creature during swimming, Oda updated the design of the tail, making it thinner and with taller inner spines, for a paddle- or fin-like shape.
The above is the second physical change that Page One's full-beast form has undergone since its debut. The first was the protruding, V-shaped eyebrow ridge that was not present in Page One's introduction in Chapter 929.
In comparison to X Drake's Ryu Ryu no Mi, Model: Allosaurus, which is based on another theropod dinosaur and more in line with late-20th-century depictions of theropods, Oda's depiction of Page One's Spinosaurus form is much more modern. It is based on the 2014 reconstruction of the dinosaur with shorter backlegs. Generally, the Spinosaurus has, compared to the Allosaurus, little in the way of older depictions that interfere with its media portrayal; the only remains of the theropod were destroyed in World War II, and it took decades to find another set of fossils, and when they were found any previous reconstructions were instantly dismissed due to the presented findings being accused of being a being incorrect. The presented "correct" skeleton was accused of being a chimera, made of more than one skeleton which caused further problems with depictions in media, including One Piece until the update in April 2020.
Spinosaurus was a semi-aquatic dinosaur built primarily for fishing. This makes this fruit the second Zoan based on a semi-aquatic species despite the principal Devil Fruit weakness to water, the first being the amphibious-based Sara Sara no Mi, Model: Axolotl.