Introducing Sinopterus(?) liui

Figure 1. Sinopterus liui reconstructed from the original tracing of Meng Xi thesis for Masters degree.

Figure 1. Sinopterus liui reconstructed from the original tracing of Meng Xi thesis for Masters degree. Note the long cervicals not found in Sinopterus.

A new, virtually complete and articulated pterosaur specimen (IVPP V14188, Fig. 1), Sinopterus liii (Meng 2015; Jiufotang Formation, 120 mya), is considered a new species of a well known genus, Sinopterus. According to Meng, distinct traits include:

  1. large body size
  2. short beak
  3. high and short skull
  4. cranially sloping crest on premaxilla
  5. well developed hatchet-shaped deltopectoral crest of humerus
Figure 2. Tapejaridae. Sinopterus liui is indeed larger than other Sinopterus specimens.

Figure 2. Tapejaridae. Sinopterus liui is indeed larger than other Sinopterus specimens. Click to enlarge. This clade evolves to greater size and greater crest size.

Only the abstract is in English. Meng also modifies the description of the genus Sinopterus (Fig. 3).

Figure 1. Sinopterus and purported juvenile, but note the skull is relatively smaller with smaller eyes in the smaller specimen. The feet are also distinct. This appears to be a smaller adult of another species, not a juvenile.

Figure 3. Sinopterus and purported juvenile, but note the skull is relatively smaller with smaller eyes in the smaller specimen. The feet are also distinct. This appears to be a smaller adult of another species, not a juvenile.

From the Meng abstract
“Studies on the cranial crest have resulted in the suggestion that the bony crest was ossified by a crest composed of soft tissue during the ontogeny. As a result, the variation of size and shape among various Sinopterus specimens may be related to ontogeny and sexual behavior. Consequently, the sole difference in the cranial crest morphology between Huaxiapterus and Sinopterus is not taxonomically diagnostic, thus we propose that Huaxiapterus and Sinopterus are synonymy. Frequent volcanic activity in this region has caused the mass mortality of vertebrates.”

So Meng is a lumper.
Unfortunately we have not been able to verify variation in size and shape (except for enlargement of a cranial crest) in any pterosaur during ontogeny — and none, so far, have been able to assigned to a gender unless an aborted egg is nearby. These observations, of course, are contra traditional pterosaur paradigms, but they do follow the data.

Figure 4. Sinopterus iui skull in situ and reconstructed using DGS. That small orbit is distinct from Sinopterus and similar to Tupuxuara.

Figure 4. Sinopterus iui skull in situ and reconstructed using DGS. That small orbit is distinct from Sinopterus and similar to Tupuxuara.

I would have given this specimen a new genus. 
Based on the low resolution images provided and the great size difference, the new specimen (Fig. 4) appears to be sufficiently distinct to warrant its own genus — but then again, all those Pteranodon specimens are lumped into one genus.

Will the lumpers and splitters please get together?

TMM 42489-2, the tall crested Latest Cretaceous large rostrum and mandible. It's a close match to that of Tupuxuara, otherwise known only from Early Cretaceous South American strata.

Figure 4. TMM 42489-2 and the Tupuxuara longicristatus, to tupuxuarids with skulls similar, but not too similar, to the new Sinopterus.

 

References
Meng X 2015. A New Species of Sinopterus from Jehol Biota and Reconstraction of Stratigraphic Sequence of the Jiufotang Formation. A Thesis for the Master Degree of Science in the Graduate School of Chinese Academy of Sciences, directed by Wang X-L. (in Chinese)

 

 

 

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4 thoughts on “Introducing Sinopterus(?) liui

  1. Going off at a bit of a tangent to your blog, but could you tell me since Huaxiapterus jii has been reclassified as Sinopterus jii, have the other two species been given a new genus name?

  2. I think you’re seeing the lumpers taking the reigns here. That’s fine as long as a phylogenetic analysis supports that branch. If we stay with the lumping of the many species in Pteranodon, then the pattern has been set for tapejarids and sinopterids. However, eyeballing the two specimens IMHO does not support such a lumping and I’ll run the phylogenetic analysis by Monday.

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