Sinopterus
Sinopterus | |
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Fossil specimen of S. dongi, National Museum of Natural Science | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Order: | †Pterosauria |
Suborder: | †Pterodactyloidea |
Family: | †Tapejaridae |
Subfamily: | † Sinopterinae
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Genus: | †Sinopterus Wang & Zhou, 2003 |
Type species | |
†Sinopterus dongi Wang & Zhou, 2003
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Synonyms | |
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Sinopterus (meaning "Chinese wing") is a
Description
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.[1] The maximum adult wingspan of this pterosaur would have been 1.9 metres (6.2 ft), and an individual of this size would have weighed 2.87 kg (6.3 lb).[2]
Classification
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,[3] though this was later disproved.[4] Some later studies found S. gui to simply represent a younger specimen of S. dongi,[5] though one large analysis in 2014 found it to be a more primitive tapejarid.[6]
A third specimen was referred to Sinopterus in 2007, again classified as a new species, this time given the name S. jii. This species was first named by Lü & Yuan in 2005 as the type species of a new genus which they named Huaxiapterus. Two later studies in 2007 and 2011 both showed that H. jii was in fact more closely related to Sinopterus than to the two other species also assigned to Huaxiapterus, "H." corollatus and "H." benxiensis. Both groups of researchers concluded that Huaxiapterus jii should therefore be reclassified as Sinopterus jii, and that the other two species of "Huaxiapterus" require a new genus name.[4][5] However, a more complete phylogenetic analysis suggested that Sinopterus may actually be an intermediate step in the grade between H. jii and the other two Huaxiapterus species, making Sinopterus paraphyletic if H. jii is included.[6]
In 2016, another species, S. lingyuanensis, was named. It purportedly differed from the other species in the proportions of its
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.[2]
In 2023, Rodrigo V. Pêgas et al. reviewed the recent taxonomic histories of the tapejarids. In their article, they made S. gui and S. lingyuanensis synonymous with S. dongi. In addition, the genus Huaxiapterus was synonymized with Sinopterus as a result of H. jii and H. atavismus being reclassified as synonyms of S. dongi and "H." corollatus being reclassified to the new genus Huaxiadraco from which Huaxiapterus benxiensis became synonymous with.[9]
Relationships
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.[6]
Tapejaromorpha |
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In 2019, a different analysis, this time by
Tapejaromorpha |
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Paleobiology
Growth
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
Based on study of hatchling Sinopterus skeletons as well as comparison with hatchlings of other pterosaur species, Naish and colleagues (2021) found that the wing proportions and bone strength/flexibility of hatchlings were similar to adults, and concluded that Sinopterus was capable of powered flight very shortly after hatching. They found that while young juveniles would have been excellent gliders, they would not have been reliant on gliding alone as opposed to true flight. Juveniles also seem to have been more adapted to flight in closed environments, like dense forests, compared to adults. Juveniles therefore probably occupied different ecological niches than adults, transitioning between different niches as they grew.[2]
See also
References
- S2CID 43993745.
- ^ PMID 34294737.
- ^ Li, J.; Lü, J.; Zhang, B. (2003). "A new Lower Cretaceous sinopterid pterosaur from the Western Liaoning, China". Acta Palaeontologica Sinica. 42 (3): 442–447.
- ^ a b Kellner, A.W.A.; Campos, D.A. (2007). "Short note on the ingroup relationships of the Tapejaridae (Pterosauria, Pterodactyloidea)". Boletim do Museu Nacional. 75: 1–14.
- ^ .
- ^ S2CID 18293296.
- ^ Lü, Junchang; Teng, Fangfang; Sun, Deyu; Shen, Caizhi; Li, Guoqing; Gao, Xia; Liu, Hanfeng (2016). "The toothless pterosaurs from China". Acta Geologica Sinica. 90 (9): 2513–2525. Archived from the original on 2016-10-11. Retrieved 2016-10-10.
- PMID 31271567.
- PMC 9922500.
- PMID 31432888.
- PMID 18268340.
- ^ Naish, Darren. "Tiny pterosaurs and pac-man frogs from hell". scienceblogs.com. Science 2.0 Corp. Retrieved 2022-06-10.