China News Service, Beijing, September 7 (Reporter Sun Zifa) On September 7, the reporter learned from the team of researcher Wang Xiaolin at the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, that the team recently conducted an in-depth study and analysis of a nearly complete right forelimb fossil of a pterosaur collected from Hami, Xinjiang, which provided new important evidence for the study of the anatomical characteristics of the postcranial skeleton of Hami Pterosaur and the allometric growth model of pterosaur growth and development.
This paper on the latest discoveries and research progress of Hamipteryx was recently published in the international academic journal "Journal of Vertebrate Paleontology".
According to the research team, Tianshan Hamipterus is a major member of the Early Cretaceous Hamipterosaur fauna in China, and is characterized by a large number of three-dimensionally preserved male and female Hamipterus skeletons, eggs and embryos at different stages of development. The fossils are mainly found in the Lower Cretaceous lacustrine strata of the Tuha Basin and are enriched in storm event sedimentary layers, reflecting the large-scale lake storms that led to the death of clusters of pterosaur fauna and rapid and specific burial.
However, the large number of bone fossils that have been discovered before are mostly scattered and isolated bones representing different individuals, and few related skeletons. Although the skull anatomy, sexual dimorphism, eggs, and embryos of Hamipterus have been studied in detail, due to the lack of associated bones, the anatomy of the postcranial skeleton is still poorly understood, especially the skeletal proportions and allometric growth of limb bones. This information can provide important basis for the growth and development, systematics, and wingspan estimation of Hamipterus.
The discovery of a nearly completely related right forelimb fossil of Hamipterus reveals for the first time the morphological characteristics of the posterior head bone of Hamipterus. Morphological comparison confirms that it belongs to the superfamily Pteranodon, and further supports its classification into the ancient pterosaur family Hamipterydae. According to the limb bone proportion data of Hamipteryx, it is found that it is closer to the northern pterosaurs and the ancient demon pterosaurs, but different from the toothless pterosaurs with extremely elongated wing metacarpal bones, and the ancient divine pterosaurs with relatively long forearms (radial and ulnar bones).
Judging from the degree of healing of the forelimb bones, the fossil specimen of Hamipteryx studied this time belongs to a sub-adult to adult individual, with a wingspan of about 1.8 meters. Compared with the previously estimated wingspan of Hamipteryx of up to 3.5 meters, this individual is relatively small. In addition, this fossil specimen, together with the currently known embryonic data of Hamipterus, provides new evidence for studying the allometric growth pattern of Hamipterus.
Combined with another partially related forelimb fossil preserved together with other individuals, judging from its bone length and bone healing degree, it also represents a sub-adult to adult individual, but its size is significantly larger than the nearly complete related fossil specimen. Therefore, the large Hamiopterus may be in a later developmental stage.
The research team said that overall, the limb bone proportions of the Hamipterus embryo and this nearly complete related pterosaur sub-adult individual are highly similar, which may reflect a unique growth strategy of Hamipterus. That is, except for the relative proportions of the forearm and the second wing phalanx, the remaining forelimb bones generally remain synchronized during the ontogeny process, that is, they grow at or near isokinetic speeds.
However, based on only the data on the developmental stages of embryos and a small amount of sub-adult individuals, and the lack of continuous evidence of other developmental stages, the possibility of allometric growth in the limb bones of Hamipteryx cannot be completely ruled out, and more fossil evidence needs to be discovered and studied in the future.
It is reported that on the eve of the 18th Annual Academic Conference of Chinese Vertebrate Paleontology and the 10th International Conference on Pterosaurs and the world's first pterosaur-themed science museum in Hami, the publication of this result is also a "congratulatory gift" to both.
