A semi-recent paper by Alifanov and Kurochkin (2011) just came to my attention. The authors presented a tiny Triassic (Madygen Formation) reptile, Kyrgyzsaurus bukhanchenkoi (Figs. 1, 2), based on a crushed anterior skeleton (sans forelimbs) and impressive skin impressions. Alifanov and Kurochkin (2011) considered it the most archaic representative of the the family Drepanosauridae (which they wrongly attributed to the Archosauromorpha).
Figure 3. The origin of pterosaurs now includes Kyrgyzsaurus, nesting between Cosesaurus and Sharovipteryx.
Alifanov and Kurochkin (2011) did not test their find against a wider gamut of taxa. They did not include Jesairosaurus, or Huehuecuetzpalli which both nested at the base of the drepanosaurs in the large reptile tree. Short trees like theirs’ are problematic at the get-go because they include no suitable outgroup taxa that would make the point that Kyrgyzsaurus would indeed nest where it does. Nor did they attempt a reconstruction. Alifanov and Kurochkin (2011) also misidentified several bones (see below for list), which is easy to do due to the crushed and slightly scattered remains.
Kyrgyzsaurus is small reptile with a 1-inch long very open skull and an elongated neck with parallelogram-shaped centra. The scapula is elongated and robust, as in Longisquama. The coracoid is quadrant-shaped, as in other basal fenestrasaurs starting with Cosesaurus. The rostrum was so short that the naris began over the premaxilla, unlike other fenestrasaurs. The skull was shorter than the cervicals, as in Sharovipteryx.
Figure 2. Updated figure of Kyrgyzsaurus. Note the tiny forelimbs and large hyoid, as in Sharovipteryx.
Kyrgyzsaurus includes a large scaly dewlap as preserved in Cosesaurus and Longisquama. A different sort of soft tissue was dorsal to the vertebrae. It was fibrous, presaging pycnofibers found in pterosaurs. Unfortunately the matrix is broken close to the body, preventing knowledge of any possible plumes along the back.
Moving the colored bones back to their in vivo positions results in a lateral view (Fig. 2) and palatal view that fits readily within all aspects of the Fenestrasauria and distinct from all other known fenestrasaurs. This was no drepanosaur, but it -was- an outgroup to all known drepanosaurs.
Kyrgyzsaurus nested in the large reptile tree between Cosesaurus and Sharovipteryx. Indeed it looks like a cross between both with that short rostrum an autapomorphy. This specimen confirms observations made in Cosesaurus and other fenestrasaurs and these suggest Kyrgyzsaurus was also a bipedal flapping taxon and possibly a glider, but not a flyer. All those extradermal membranes were secondary sexual traits. So was flapping. These were the birds-of-paradise of the Triassic.
The size is similar to other fenestrasaurs indicating that all known specimens are adults.
Even though the forelimbs are missing, the elongated scapula and stemmed coracoid are identical to those found in Langobardisaurus and Cosesaurus through pterosaurs. Earlier we discussed how these were different than those of quadrupedal tritosaur lizards and that birds, bats and pterosaurs all have a similar morphology for flapping.
The Madygen Formation also yielded Sharovipteryx and Longisquama, so this is confirmed as the birthplace of the pterosaurs. If we keep looking here we will find a larger variety of fenestrasaurs. Alifanov and Kurochkin (2011) listed several papers describing Longisquama and Sharovipteryx, but failed to mention any of my papers, so once again these paleontologists turned a blind eye to the most parsimonious hypotheses out there. That’s a shame. Ultimately, as in this blog, their mistakes and oversights will be revealed.
Alifanov and Kurochkin (2011) misidentified the dorsal scapula as a single high neural spine. They thought the lower jaw was shorter than the upper at their tips. The occiput was overlooked as it sits on top of the parietal. What they considered the occiput are the first two cervical vertebrae. What they considered the occipital condyle is the posterior cervical vertebrae 2 extending below cervical 3, as in all the other cervical vertebrae and as in pterosaurs and other fenestrasaurs. What they considered broken maxilla is the sclerotic ring. What they considered the sclerotic ring is the squamosal and the postorbital. What they considered the arch of the hypoglossal apparatus is the main portion of the quadrate together with the much thinner hyoid. Their quadrate is the pterygoid process of the quadrate. Their maxilla is actually the ectopalatine (ectopterygoid + palatine). It might have tiny teeth. Their nasal is the ascending process of the premaxilla. The more slender thoracic spine is the ventral stem of a displaced coracoid. The lacrimals and prefrontals were overlooked entirely.
Making a reconstruction is key to double-checking the identities of crushed bones as in this specimen. You know the whole thing is there. You know what bones to look for. Putting them back together confirms identities.
Alifanov and Kurochkin (2011) reported, “The new species is referred to drepanosaurids based on the large nares and orbits, low position of the quadrates, the absence of gradual transition between vertebrae of the cervical and thoracic regions, arched clavicles, subtriangular section of thoracic ribs, and cranial inclination of the dorsal end of the scapulae.” In the new reconstruction, the naris is not so large, the quadrates are just as low, the transition between the cervicals and thoracic vertebrae is gradual, clavicles are not arched, but fused to the sternal complex, the thoracic ribs are indeed subtriangular in section (not sure how this relates to drepanosaurids) and the scapulae are not cranially inclined. Their big mistake was not correctly identifying the displaced scapula and coracoid, considering both to be vertebral spines. Drepanosaurs nest close to fenestrasaurs in the large reptile tree.
And the rest of Kyrgyzsaurus?
Phylogenetic bracketing permits us to imagine a long-torso fenestrasaur with long hind limbs and an attenuated tail. The pelvis could be deep or shallow, but the ilial processes would be elongated. A prepubis and pteroid would be present. Whether the forelimbs were shorter or longer depends on whether Kyrgyzsaurus was closer to the lineage of Sharovipteryx or Longisquama. Considering the size of the scapula, I would guess the latter was more probable.
I dream of finding more fenestrasaurs like this. Thank you, very much, Wm. Parker for sending the pdf!
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
Alifanov VR and Kurochkin EN 2011. Kyrgyzsaurus bukhanchenkoi gen. et sp. nov., a new reptile from the triassic of southwestern Kyrgyzstan. Paleontological Journal 45(6): 639–647. doi:10.1134/S0031030111060025.