According to reports: fossils of pterosaurs that have so far preserved the basal hyoid bone have been found. Previously, studies on the pterosaur hyoid bone were relatively sporadic, and this was the first time that a more systematic fossil of the pterosaur hyoid bone was found.
Hyoid apparatus, in most living birds, consists of a pair of thin stick-like hyoid bones and superior hyoid bones with varying degrees of ossification, the basal and coccyoglossoid bones in the middle part of the hyoid bones, and the paratyoid bone composed of cartilage at the very tip of the basal hyoid bone. In pterosaurs, only thin stick-like hyoid bones have been found before, so they have long been thought to be very similar to the hyoid bones of birds. In this new specimen temporarily classified as Gladocephaloideus jingangshanensis, a long-triangular basal hyoid bone was first discovered, and based on the expansion of the anterior front of its horned hyoid bone and the fact that most of the pterosaurs known to preserve the horned hyoid bone had this feature, it is speculated that the basal hyoid bone may have existed in many types of pterosaurs, but it is not preserved because it is not ossified or completely ossified.
By comparing the proportion of the length of the hyoid bone and the skull of the pterosaur horn that has been found in the world, it is believed that in the evolution of the pterosaur, the length of the horned hyoid bone is gradually shortening relative to the length of the skull, which may represent the gradual weakening of the ability of the tongue of the pterosaur to shrink backwards, of which the ratio of comb-jawed pterosaurs and Gallic pterosaurs is the smallest, and the King Kong sword-headed pterosaur that preserves the base hyoid bone belongs to the Gallic pterosaur class, which may represent one of the types with the shortest relative length of the hyoid bone in the pterosaur.
In the process of gradually shortening the pterosaur hyoid bone relative to its skull, the sail pterosaurs evolved a special Y-shaped hyoid bone, composed only of the horned hyoid bone, the front end gradually became thinner and sharper, no expansion, no basal hyoid bone. Previous researchers have believed that the two horned hyoid bones of this pterosaur were healed at the front end and may have a habit similar to that of chameleons popping out their tongues to prey. By observing the orthodontic specimen of the most representative of this type of hyoid bone, the Liaoxi Pterodactylosaurus and further repairing the hyoid bone of the orthodon specimen of nurhachiptera, which also belongs to the class of Sail Pterodactyl, it was found that the anterior end of the Y-shaped hyoid bone did not heal, but only two close together, and a careful comparison with the color-changing kewpaw also found that it was completely different from its powerful catapult structure, so the sail pterosaurs were not pterosaurs with insectivore habits like chameleons.
In addition, the particularly elongated hyoid bones of the sail pterosaurs represent the muscles that cause the tongue to contract backwards compared to the shorter type (M. serpihyoideus and M. stylohyoideus) is longer and more developed, so the ability of these pterosaurs to transport food into the mouth is also more prominent. Features such as the lateral flattened diamond teeth of the sail pterosaurs and the posterior protrusion of the lower jaw also supported the previously thought scavenger lifestyle of the sail pterosaurs.