Sinopterus

of S. dongi Sinopterus is known from numerous specimens, some of which have been assigned to unique species and even different genera over the years. The type species, Sinopterus dongi, is known from one specimen described in 2003. A second specimen, BPV-077, was also described in 2003 by Li, Lü, and Zhang, who classified it in its own species, S. gui. It was said to differ from S. dongi mainly in its smaller size (only about half the size of S. dongi) and the presence of a notarium, though this was later disproved. Some later studies found S. gui to simply represent a younger specimen of S. dongi, though one large analysis in 2014 found it to be a more primitive tapejarid. However, Xinjun Zhang and colleagues in 2019 considered Huaxiapterus an invalid genus and therefore reassigned H. atavismus to Sinopterus, which created the new combination Sinopterus atavismus. A 2021 study by Darren Naish and colleagues of variation within pterosaur growth stages noted that numerous species had been classified as Sinopterus or "Huaxiapterus", most based only on a single specimen, and most differentiated from each other by features like wing proportions, skull length, and crest shape and size. Naish et al. pointed out that all of these features are known to be variable within a single species due to growth, and that there were unlikely to be such a high diversity of extremely similar species in the same ecosystem when their differences are more likely due to variation within a few species. They suggested that a larger study would be needed to untangle the question of how many species of Sinopterus-like pterosaurs actually existed in the Jiufotang ecosystem, and how they are related to each other. In a preliminary opinion, these scientists stated that there is likely only one valid species of Sinopterus, S. dongi, but that "Huaxiapterus" corollatus might be a valid second species based on unique wing and leg proportions. ==Description==

of Sinopterus and Huaxiadraco in Jiufotang The type species, S. dongi, is based on IVPP V13363, an articulated, nearly complete skeleton. The skull of this individual was 17 centimeters (6.7 inches) long, and the wingspan was estimated to be 1.2 meters (3.9 feet). The authors suggested that it was an omnivore, and noted that it was the first record of a tapejarid outside of Brazil, and the earliest and most complete tapejarid. The maximum adult wingspan of this pterosaur would have been , and an individual of this size would have weighed . ==Classification==

of S. dongi The cladogram below follows the 2014 analysis by Brian Andres and colleagues, showing the placement of two Sinopterus species ("S." gui and S. dongi) within the clade Tapejaromorpha. Based on their reassessment of the Sinopterus species-complex, Pêgas et al. modified their working dataset, previously used in the redescription of Aerotitan. Their cladogram is shown below: ==Paleobiology==

Growth specimen IVPP V-14377, which may be Sinopterus'' Sinopterus is known from several specimens at various stages of growth, which has allowed scientists to study the changes these animals went through during their life histories. At least one very small juvenile (possibly hatchling) specimen has been attributed to Sinopterus. This specimen was originally classified as a distinct genus in 2008, Nemicolopterus crypticus. The name Nemicolopterus comes from the Greek words "Nemos" meaning "forest", "ikolos" meaning "dweller", and the Latinised "pteron" meaning "wing". The specific name crypticus is derived from the Greek "kryptos", meaning "hidden". Thus "Nemicolopterus crypticus" means "Hidden flying forest dweller". The type specimen of N. crypticus, catalog number IVPP V-14377, is housed in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China. The fossil was collected from the Jiufotang Formation, like all adult Sinopterus specimens. It was discovered in the Luzhhouou locality of Yaolugou Town, Jianchang County, Huludao City, western Liaoning Province in northeastern China. It has a wingspan of slightly under 25 centimeters (10 in), making it smaller than all but a few specimens of hatchling pterosaurs. of two Nemicolopterus Wang et al. (2008), who originally described the specimen, concluded that it was immature, citing the amount of bone fusion and the ossification of the toes, gastralia, and sternum as indicating that it was a sub-adult rather than a hatchling. However, Darren Naish argued on his popular weblog that, due to the hypothesis that pterosaurs were highly precocial, bone fusion and ossification could have occurred very early in life, and that Nemicolopterus might in fact be a hatchling Sinopterus. Diet skulls, Sinopterus is F Tapejarids like Sinopterus have long been speculated as having been frugivores or omnivores, based on their parrot-like beaks. In 2025, the palaeontologist Shunxing Jiang and colleagues reported stomach contents from the abdominal cavity of a Sinopterus specimen. These include gastroliths (stones used to aid food processing in the gizzard) and the first evidence of phytoliths in pterosaurs (minerals found in certain plants which persist after their decomposition), and the first evidence of these co-occurring in a pterosaur. Earlier known pterosaur stomach contents are all from more basal pterosaurs, containing fish remains. The gizzard of the Sinopterus specimen is similar to that of the bird Jeholornis, and the pattern and size of their gastroliths are similar; since both belonged to the Jehol Biota, these writers suggested they shared a herbivorous diet such as seeds and grains. Some of the phytoliths of the specimen were identified as the angiosperm family Poaceae as well as gymnosperms or ferns, indicating Sinopterus had a diverse diet of plants. While noting that tapejarids and some other pteosaurs had earlier been suggested as herbivorous based on indirect evidence, these researchers considered the gut contents confirmation of herbivory, and excluded a generalist diet for Sinopterus as for example no undigested bones, scales, or insect exoskeletons were found. They also stated that bite force estimations of Tapejara had suggested a herbivorous diet of fruits, seeds, and more resistant plant matter, and added that the similarity between their skulls indicated similar bite forces, supporting a herbivorous diet for both. ==See also==