Reconstructing Sharov’s Longisquama

My detractors often point to my discovery of the second half of Longisquama as pure fantasy.

So let’s pretend
that the back half of Longisquama was never present in the fossil. Pretend, like Jimmy Stewart in a Wonderful Life, that I was never born.

Now the onus
goes back to all the pterosaur workers who still refuse to examine the very pterosaurian traits of Longisquama, as traced by Sharov (1970, Fig. 1). Those traits are still there, whether I point them out or not.

Figure 1. Longisquama as traced by Sharov 1970. Workers have been searching for the predecessor of pterosaurs. Why didn't they look here?

Figure 1. Click to enlarge. Longisquama as traced by Sharov 1970 above, reconstructed below using DGS to move Sharov’s lines around. Workers have been searching for the predecessor of pterosaurs. Why don’t they look here? According to Sharov Longisquama has a sternal complex (he saw the displaced, fused clavicles, but not the sternum they rimmed), antorbital fenestra, long 4th finger (the actual 4th finger is much longer) and membranes trailing the forelimbs, not to mention a strap-like scapula and elongate coracoid. What more could you want? Alongside, not to scale, long-necked Sharovipteryx and short-necked MPUM6009, a basal pterosaur. Yellow displaced “plumes” are actually the tibia and femur, so the hind legs have been seen, just misidentified.  Those two bumps on the head are really a displaced parietal rimming upper temporal fenestrae. A little more resolution would clear this up.

So many fantasy creatures
have been built around the idea of Longisquama (just Google it), but no one has taken Sharov’s blueprint and put the bones back into their in vivo positions — until now (Fig. 1). When you repeat this experiment, you will also get something that can be input into phylogenetic analysis. And the rest (the blue areas) can be guesstimated based on phylogenetic bracketing. Almost all other artists put much smaller hind limbs on Longisquama, but that’s not what close relatives have (Fig. 1).

Like a basal pterosaur Longisquama has this suite of characters:

  1. an antorbital fenestra
  2. a large orbit
  3. multicusped teeth
  4. short neck (eight cervicals)
  5. 9th vert has short rib, 10th vert has rib that contacts sternal complex
  6. strap-like scapula
  7. narrow coracoid
  8. sternal complex (clavicles wrapped around sternum + interclavicle)
  9. parallel ulna and radius
  10. asymmetric manus with short digit 5
  11. structured membrane trails forelimb (proto-wing)
  12. small membrane precedes forelimb (proto-propatagium)

Everything else we’ll call guesswork
based on phylogenetic bracketing, which is, by definition, extremely conservative. Phylogenetic bracketing gives Longisquama long hind limbs, uropatagia, an attenuated tail and a short mt5 + elongated p5.1, just like it’s sisters.

Sharov’s traits alone
are enough to call this specimen out as the best candidate for pterosaur kinship — and yet — it’s been ignored and dismissed for forty years — even with that PR bump in 2000 and 2002. With such data widely available, does anyone else think it is very odd that professionals who write pterosaur books (Wellnhofer, Witton and Unwin) and other professors (Bennett, Padian, Hone, etc. etc.) claim we don’t know the ancestry of pterosaurs? Or am I the only one who finds this odd and unsettling?

I can understand why they would ignore me, a published amateur widely despised and ridiculed. But why ignore Sharov?

Evidently it’s a mind set.
And it’s hard to break, even with Sharov’s own images. He saw what I saw. I just added details.

New tracings of Longsiquama

Figure 2. Click to enlarge. New tracings of Longsiquama (B) soft tissues and (C) bones.

If you want to learn more details about the Longisquama fossil, find them here.

 

Figure 3. Click to enlarge. If you still don't like Longisquama, there's more where that taxon came from. Any one of these will nest closer to pterosaurs than any archosauromorph. Here's Kyrgyzsaurus to scale alongside other basal fenestrasaurs, Cosesaurus, Sharovipteryx and Longisquama. Kyrgyzsaurus likely was a biped with long legs. We know from the shape of its coracoids that it was a flapper.

Figure 3. Click to enlarge. If you still don’t like Longisquama, there’s more where that taxon came from. Any one of these will nest closer to pterosaurs than any archosauromorph. Here’s Kyrgyzsaurus to scale alongside other basal fenestrasaurs, Cosesaurus, Sharovipteryx and Longisquama. Kyrgyzsaurus likely was a biped with long legs. We know from the shape of its coracoids that it was a flapper.

References
Bennett SC 2008. Morphological evolution of the forelimb of pterosaurs: myology and function. Pp. 127–141 in E. Buffetaut & D.W.E. Hone (eds.), Flugsaurier: pterosaur papers in honour of Peter Wellnhofer. Zitteliana, B28.
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. Historical Biology 15: 277-301.
Senter P 2003. Taxon Sampling Artifacts and the Phylogenetic Position of Aves. PhD dissertation. Northern Illinois University, DeKalb, IL, 1-279.
Senter P 2004. Phylogeny of Drepanosauridae (Reptilia: Diapsida) Journal of Systematic Palaeontology 2(3): 257-268.
Sharov AG 1970. A peculiar reptile from the lower Triassic of Fergana. Paleontologiceskij Zurnal (1): 127–130.

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