A day with John Conway’s Pteranodon

Scott Hartmann’s wonderful blog skeletaldrawing.blogspot.com featured a day with paleo artist, John Conway here. Conway’s work, seen on his website, is unique, insightful, fanciful and beautiful. He has a great following and counts among his friends many, if not all, of the Pterosaur.net folks, a website he contributes to. Unfortunately I seem to have a constant feud with the pterosaur.net folks, to be candid, which is one of the reasons why I started this blog.

It’s important to be accurate
Most of John’s work sparkles with accuracy and artistry. Unfortunately, John’s Pteranodon skull is largely based on the restoration by Bennett (1991, 2001) which was based on several specimens, but chiefly it appears based on the skull of KUVP2212 (Fig. 1). Conway accurately portrays the Bennett restoration and the skull of KUVP2212, but the actual specimen is a chimaera (built from several specimens). So, the post-crania of KUVP2212 do not belong with the skull, but are stitched together like a Frankenstein monster to make a complete display. (That’s what they did back then to make a pretty and spectacular display). If  Conway bought into or depended on the chimaera of Bennett’s restoration or KUVP2212 this may explain some of the problems found here. My email to him on this matter has gone unanswered.

Although I usually take inspiration from Conway’s work, the proportions of John’s Pteranodon along with some of the configurations he sets it in seem to be a wee bit off. I’ll point out my concerns using evidence from other more complete and singular Pteranodon specimens.

Note!
I’m not telling you to avoid all of John Conway’s work (which would follow the less than scientific patterns set in 2012 by paleontologists and paleoartists Darren Naish and Mark Witton). Even so, John is not blameless here. He promoted Gothic pterosaur illustrations purportedly based on my hypotheses and, at one time, some blogs falsely attributed that horrorshow to my hand. I would have preferred that he and others would have used my actual illustrations, to be more fair and accurate. And to use the latest work, not things I’ve thrown away many years ago.

That’s why I’m using John’s own images, without distorting them. Here (Figs. 1-3), I’m just pointing out inaccuracies and accuracies with one set of illustrations produced by Conway. Here the facts should speak for themselves and only need a finger to point them out.

wo of the most completely known Pteranodon

Figure 1. Two of the most completely known Pteranodon specimens (UALVP24238 and NMC4138) along with the skull of KUVP2212 to scale. In purple, John Conway’s Pteranodon with a too  small skull and an  odd elbow-high walking configuration. The Conway wings are more robust, but other Pteranodon specimens had more robust wing bones than does the Triebold specimen (see links in text), as can also be imagine by the porportions of the UALVP specimen, above.

Back to Pteranodon
Just one look at two other more complete and closely related Pteranodon specimens (Fig. 1) shows there is great variation in this genus. Even more so when you consider most of the Pteranodon skulls or post-crania without skulls now known. That’s good background material. Now, on to Conway’s artwork…

One reconstruction vs. another
Above is the Conway reconstruction (in purple, evidently based on a chimaera of specimens) alongside my own reconstructions based on the two most complete Pteranodon specimens now known.

Easy to see
1. the Conway Pteranodon skull is only 2/3 as large as it should be based on the non-chimaera specimens and the actual skull of KUVP 2212.

Not so easy to see:
2. Conway includes a smaller scapulocoracoid, which, by its brevity, raises the sternal complex and slants the ribs too far backward and gives Pteranodon a bulging belly. Now, this may be based on the UALVP specimen, which does have a different profile than the Trielbold/NMC specimen, larger humerus, larger sternal complex, etc. Yes, they’re both to the same scale and the variation plainly goes beyond gender or ontogeny.

3. Conway puts the center of balance, the wing root, over the fingers, just beyond the toes. Thus the largely vertical metacarpus requires an elbow-high configuration, unlike that of other pterosaurs with a more relaxed elbow in line with the torso. Conway’s reconstruction puts the shoulder and elbow joints at the extremes of their movement ranges, rather than in the neutral range, as in the Peters configuration. Perhaps Conway is anticipating a forelimb leap.

4. Conway extends the knee joint such that the femur and tibia are nearly aligned, as in humans, rather than at right angles, as in lizards and other reptiles, including birds. Such a configuration disarticulates the distal femoral condyles from the tibia. This also misaligns the prepubes with the femora, which Peters aligns. The Peters configuration also places the femur at right angles to the ilium, but the Conway configuration sets the femur at a further posterior extreme.

5. Conway puts the pteroid in the cup of the preaxial carpal. Peters puts the pteroid on the saddle joint of the proximal carpal (radiale) as confirmed by Kellner (2012) and every other articulated pterosaur.

Anterior view of Pteranodon by Conway.

Figure 2. Anterior view of Pteranodon by Conway (sans skull). Here the elbows are high, which is an excellent way to add curvature to the wing membrane. If you look closely the metacarpals are stacked, palmar side forward, and high, which would produce pterosaur handprints with all three digits extending posteriorly, which is not the case in pterosaur fossils. I’d also fill in the space between the sternal complex and deltopectoral crest with more muscle.

In anterior view
the Conway reconstruction correctly raises the elbow higher than the wrist, adding curvature to the extended wing. Unfortunately Conway stacks the metacarpals so their palmar sides face anteriorly in flight, following the very strange and untenable hypothesis of Bennett (2008) detailed and criticized here (and see Fig. 3). This configuration provides no room for the extensor tendon of the wing finger (Fig. 3) and, when the fingers do extend, all three would extend posteriorly, which is not reflected in the fossil track record. The Peters configuration keeps the fingers palmar side down (Fig. 3), as in other tetrapods, so the fingers extend laterally as reflected in the fossil record. Only digit 3 extends posteriorly due to a more spherical, lizard-like metacarpophalangeal joint as discussed here.

The fragile hinge binding tiny metacarpal 3 to giant metacarpal 4 forms a metaphorical drawbridge when the extensor tendon rots away, creating the misleading interpretation of the palmar side facing anteriorly as the set rises until stopped in bottom currents. When the wing is preserved anterior side down as shown here, the correct order and configuration is maintained during burial. When the wing is preserved dorsal side down the drawbridge affect raises the three conjoined metacarpals ventrally as a unit, proving my point.

Pterosaur finger orientation in lateral view

Figure 3. Pterosaur finger orientation in lateral view, the two hypotheses of the evolution of the pterosaur manus by Bennett and by Peters. In Bennett’s view the entire manus rotates palmar side forward, digits 1-3 migrate as a group to the middle of the palmar side and there is no room for the extensor tendon, among other more ghastly problems.  In the Peters scenario the only thing that happens is an axial rotation and enlargement of metacarpal 4.

In dorsal view (Fig. 4) the flying Pteranodon of Conway likely has too much extended soft tissue that is not shown in the Zittel wing, for instance. It’s a nice thought, creating a thicker, more airplane-like wing, but such tissue would likely interfere with folding.

 Conway Pteranodon in dorsal view.

Figure 4. Conway Pteranodon in dorsal view. The black and dark gray areas are hypothetical soft tissue.

Conway is correct in his shallow-at-the-elbow wing membrane configuration. And that’s great. Drawing that configuration Conway breaks from the paradigm of the pterosaur.net folks.

In my opinion, the humerus extends too far laterally in the Conway reconstruction and so does the forearm. This is a common an oft repeated error (Fig. 5). The basic pterosaur wingshape is shown here (Fig. 5) in which the elbows are further back, the elbow extends no more than 110 degrees and the metacarpus aligns with the wing finger creating a rather straight sailplane-like wing. In flight the tibiae would have extended to their limits on the femora creating a wider horizontal stabilizer held that way with little effort by the aerodynamics of the webbed feet, now held palmar side medially like twin rudders.

Figure 8. Click to enlarge. Problems with the Elgin, Hone and Frey (2011) pterosaur wing model with corrections proposed by Peters (2002).

Figure 5. Click to enlarge. Problems with the Elgin, Hone and Frey (2011) pterosaur wing model with corrections proposed by Peters (2002). And yes, they tried to cheat the look (lower right) by redrawing my configuration to make it look bad. Use these illustrations, guys!! Don’t cartoon your own and pass it off as mine. Note: Conway’s pterosaur wings are not quite like either of these.

To John’s credit, I was inspired to redo the ribs on the Triebold specimen, which is one of my oldest reconstructions. I angled them further back, which shifted the sternal complex further back.

I encourage all observers of paleoart to see with two sets of eyes, one for accuracy and one for beauty. And do visit johnconway.co when you have a chance to. It’s a rich and rewarding experience.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodon and Systematics of the Pterodactyloidea. [dissertation]  University of Kansas. Available from University Microfilms Int. no. 9238613. 680 pp.
Bennett SC 2001. The osteology and functional morphology of the Late Cretaceous pterosaurPteranodonPart I. General description of osteology. Palaeontographica, Abteilung A, 260: 1-112.   Part II. Functional morphology. Palaeontographica, Abteilung A, 260:113-153.
Bennett SC 2008. Morphological evolution of the forelimb of pterosaurs: myology and function. Pp. 127–141 in E Buffetaut and DWE Hone eds., Flugsaurier: pterosaur papers in honour of Peter Wellnhofer. Zitteliana, B28.
Elgin RA, Hone DWE and Frey E 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica 56 (1), 2011: 99-111. doi: 10.4202/app.2009.0145
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.

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