Art Day, for Tapejaroidea


Tapejaroidea on Parade

Tapejaroidea, a clade of pterosaurs that might also be called Lophocratia, depending on whom you ask, represent a diverse clade of mostly toothless pterosaurs. They represent mostly one half of the Pterodactyloidea, the other being Ornithocheiroidea (or Euornithocheira). [It’s something of a boondoggle, the taxonomy of Pterosauria, due to the fact that two different and competing sets of names are used by mutually exclusive groups of pterosaur systematists; you’d think someone should just come in and settle the bloody thing once and for all.]

Shown from left to right are a “germanodactylid” (or basal dsungaripteroid, though considered in some analyses to be closer to ctenochasmatoids), a thalassodromid/tapejarid, an azhdarchid, a chaoyangopterid, and a more sensible dsungaripterid (or, one peering around the corner of the page). All animals are depicted in the quadupedal stance of general terrestrial locomotion, dispensing with the idea that they were bipedal in any fashion, while also covered head-to-toe and wintip-to-wingtip in “pterofuzz” (pycnofibres). Wings are tucked in “terrestrial” mode, and this can do funny things to the shape and relationship of the wing membrane (cheiropatagium, broadly).

The style here is pretty useful for characterizing a simple drawing showing proportions, stance, and attitude. I characterize the species merely walking, mostly largely doing the same thing, which helps the viewer to compare them easily side by side, get a sense of proportion or scale. In these, though, scale is less important than shape differences in body outline, something much more difficult to do with varying perspectives or even “in flight” depictions. Indeed, pterosaurs are so often shown flying, taking off in various ways, or landing that there is an essential dearth in “grounded” views, walking, or idling. I’ve shown pterosaurs before in “non-standard” perspectives, but that was only preparatory. There is a high degree of utility in “side-view” depictions, as it is otherwise impossible to describe scale when trying to be “realistic” in scaling and perspective but also show comparison between two animals. Artistically, one can show this by coloring, but that doesn’t tell you much about physical details, and indeed can obscure actual details; the artist is spending more time showing colors than showing shapes that actually distinguish the two. Of course, in some animals, the “standard” differs, so that in ceratopsians, the best way to show off the head is in fact a dorsal view of the head/skull, rather than a side view, due to the shape of the frill, horns, spikes, etc. [though I’ve differed occasionally, as in this piece, which also just so happens to show nonmuscular “cheeks”.] But that doesn’t really work on crest pterosaurs, as the crests are often very, very thin and form large semi-circular/ovate “plates” standing on-end.

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7 Responses to Art Day, for Tapejaroidea

  1. Simlpe but very effective. Great work.
    Also, “original” the uropatagium feature insted of the cruropatagium one. Exactly, why this choice?

    • Mostly it’s because I’m pulling the cruropatagium up close to the leg in profile, with a tight curve close to the body wall rather than letting the edge slack down close to ground level. The primary reason for that is due to the problems of walking around in brush with the edge of your wing scraping twigs, brush, rocks, etc. This is my biggest problem with modeling the quad-stance in pterosaurs from other artists, such as Mark Witton (however otherwise excellent). Here, function should restrict form.

  2. you’d think someone should just come in and settle the bloody thing once and for all.” Has been done with many more taxa than anyone else – http://www.reptileevolution.com/MPUM6009-3.htm.

    I notice you’re extending the toes prior to pedal liftoff, as in most tetrapods, But traditional reports say this is impossible due to joint limitations. I don’t agree with those traditions and I applaud your rendition of the feet here.

    It’s important to match the distance between implanted hands with the distance between implanted feet. If the distance between the hands exceeds that of the feet, they are moving faster than the feet, which can’t last for long.

    I think that, as in bats, the wing membranes would shrink to almost nothing visually while folded, as we can also see in many pterosaur fossils that preserve wing membranes.

    Have you tried moving the knees a little forward, in line with the prepuces? If so you’ll see the feet implant below the glenoid when the pterosaur is not moving, which means it can balance over its feet, leading to the possibility of a bipedal takeoff and landing.

    I applaud your shortening of the proximal wing membrane to the knee, which is supported by all available fossils (I would move to mid thigh to be more accurate) and avoids the droopy membrane connected to the ankles which you also see as untenable.

    This pseudo clade, the Tapejaroidea, needs to be divided between the sharp jaw tips and the non sharp jaw tips at its base. In my work the sharp tips are derived from Germanodactylids. The azhdarchids from Dorygnathus. More taxa resolve this issue.

    Finally, overall your renditions have great personality and are very attractive.

    Best, Dave Peters

    • When it comes to pterosaur taxonomy, I am referring to the differing definitions or uses of terms among the many competing analyses. None of them are consistent, and none of them necessarily follow what the others are doing. This problem isn’t “solved” by adding another idea to the mix.

      As for mobility and stance with membranes, flexibility is not the issue: The cruropatagium may differ among taxa, but in a large number of them it is fairly slender and would have aligned close to the body with the wing folded or extended, unless the wing were swept back in which case I imagine it possible the cruro/cheiropatagial transition to have a longer chord than otherwise.

      Stance would not necessarily alter this. Suffice it to say that I do not think pterosaurs were faculative bipeds, should have been more bipedal than quadrupedal, but that they were obligate quadrupeds with some bipedal stance capability. The type of stance or even locomotion required you argue for has NOT necessarily been demonstrated with models using body mass values and CoG placement with respect to stance or locomotion, especially when dealing with small-legged pterosaurs. The problem increases with long-legged pterosaurs in which, amazingly, the antebrachium appears elongated to a similar fashion (especially note dsungaripterids, azhdarchids and ctenochasmatids), suggesting coupling of forelimb to hindlimb during terrestrial locomotion. I think Darren Naish and Mark Witton went over this in their papers on azhdarchid locomotion/habitus. Please feel free to correct me with hard data.

    • As an additional point, to be brief, it should be noted that the clade Tapejaroidea is typically used in a cladistic sense; that is, it has a phylogenetic definition. Including the fact that “Tapejaroidea” essentially corresponds to a Linnaean “superfamily” in its original wording, and must exist so long as one uses the Linnaean System and Tapejaroidea (as a “family”), there will always be a “Tapejaroidea.” It doesn’t matter if this definition changes, either, expanded or restricted. The issue i raised with Lophocratia (briefly) was that it may correspond to the same content as Tapejaroidea, but is or can be used in lieu of it. It may even have a different definition but have the same content.

  3. As a brief note: the distance between manus strikes and pedal strikes can differ if the duty factors are not equal, which is plausible for pterosaurs.

    • That makes sense, Mike, though i notice that in higher disproportion between limbs as with many ornithocheiroids this would be more common than with, say, tapejaroids where the “effective” limb length (antebrachium/leg) is closer to equal. Obviously, the duty would lie stronger in the forelimbs for all pterosaurs, but less so as the hindlimbs become closer to the antebrachium length, and the antebrachium doesn’t become much, much heavier (as it does in azhdarchids, I think — they seem to have a denser trabecular system than other tapejaroids).

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