Why do pterosaur workers ignore the most basic data?

I don’t know why,
but today’s leading pterosaur experts are actively ignoring the data from the last twenty years while inventing their own fanciful versions of what pterosaurs looked like (Fig. 1) – while claiming to be the latest word on the subject. Today we’ll be looking at a short paper from the latest Flugsaurier book by Hone, Witton and Martill 2017. And we’ll criticize the artwork that crystalizes their latest intentions. This is part 1.

For some reason
Hone, Witton and Martill like to show ancient cartoons that have little to no bearing on the present knowledge base (Fig. 1). I think it’s an English thing since most, if not all of the old engravings are indeed English in origin and easily lampooned. ‘See how far we’ve come!’, they seem to be saying. Doing so only takes up space that could otherwise go to competing current versions – which they want to avoid.

We’ve seen this
earlier when English professor D. Naish preferred to criticize work that preceded (= was not included in) ReptileEvolution.com. He employed cartoons made by others, rather than artwork that was actually posted on the website to show how bad the whole website was.

It’s what they like to do. Someday, perhaps, they’ll look in a mirror and see some of the faults I present here… using their own artwork – which will soon enough joint their ancient engravings in a drawer full of foolish ideas they can draw upon in future decades.

Figure 1. Images from Hone, Witton and Martill 2017 showing the 'evolution' of our concept of Dimorphodon. Compare the latest color version to tracings of the several skeletons in figure 2.

Figure 1. Images from Hone, Witton and Martill 2017 showing the ‘evolution’ of our concept of Dimorphodon. Artists are credited in the text. Compare the latest color version to tracings of the several skeletons in figure 2. The long tail is based on a disassociated fossil probably belonging to a campylognathoid.

In figure 1
images of Dimorphodon through time are presented from Hone, Witton and Martill 2017.

  1. Rev. GE Howman 1829. Probably based on the headless holotype BMNH R1034 (Fig. 2). The authors labeled this as ‘monstrous’ when ‘inaccurate’, ‘fanciful’ or ‘medieval’ would do.
  2. Owen 1870. Probably based on the short-skull specimen, BMNH 41212 (Fig. 2), along with the disassociated tail specimen. The authors labeled this rendition as ‘ungainly, bat-like’. Odd word choice when among all the presented illustrations it is the one most like Witton’s 2017 version (#5).
  3. H Seeley 1901. Probably based on the long-skull specimen, BMNH PV R 1035 (Fig. 2) In the their comment Hone, Witton and Martill report, ‘progressive interpretation of D. macronyx as an erect-limbed quadruped’, but note that a biped interpretation was also offered. They thought it best not to show that possibility. 
  4. K Padian 1983. Probably based on the short-skull specimen, BMNH 41212 (Fig. 2). The authors report, ‘a highly active, bird-like digitigrade biped, a controversial interpretation that nevertheless symbolises the reinvention of pterosaurs in the late twentieth century.’ While there are minor issues associated with this figure (the orientation of fingers 1–3 and pedal digit 5, the over-extension of the metatarsophalangeal joint, the great length of the tail), it is the one that is most closely based on the skeleton (Fig. 2). BTW, when authors use the word, ‘controversial’ it usually means it does not fit their world view, but they have no evidence against it, nor any evidence to support their traditional hypothesis. 
  5. M Witton 2017. Not sure which skeleton this one is based on as it appears to have been done entirely freehand from memory and imagination. The authors report, ‘Modern interpretation of D. macronyx adult and speculative juveniles reflecting contemporary interpretations of pterosaur soft tissues, muscle development and ecology.’ Ahem…we’ll run through this illustration step-by-step below.
Figure 2. Images of Dimorphodon from ReptileEvolution.com. The tail attributed to Dimorphodon is shown in figure 3.

Figure 2. Images of Dimorphodon from ReptileEvolution.com. The tail attributed to Dimorphodon is shown in figure 3.

You know, you really can’t go wrong
when you strictly adhere to the bones (Figs. 2,3), soft tissue (Peters 2002) and footprints of the most closely related taxa (Peters 2011), which were made by digitigrade and bipedal pterosaur trackmakers. Unfortunately no such citations appear in this chapter. Those are purposefully omitted.

Dimorphodon model by David Peters

Figur 3. Dimorphodon model by yours truly. The tail is too long based on the disassociated tail.

fell under the spell of the quad-launch hypothesis (Habib 2008), then took it one step further and made Dimorphodon a galloping hunter (Fig. 4), forsaking its wings and erect, digitigrade hind limbs (according to related ichnite makers) to hunt prey on mossy logs with backward pointing fingers. The finger unguals are again too small here.

While writing this I became aware
of Sangster 2003, a PhD thesis that evidently used computer modeling to show Dimorphodon was a quadruped. I have not seen the thesis and Ms. Sangster can no longer be found online. I wonder about these conclusions because:

  1. PhD theses are, by definition, the work of inexperience workers; and
  2. Sangster may have had to earn her PhD by succumbing to the unveiled interests of her English professors, as we’ve seen before here and here.
Figure 4. Galloping Dimorphodon by Mark Witton.

Figure 4. Galloping Dimorphodon by Mark Witton.

To counter the awkward, dangerous and ultimately unproductive
quad-launch scenario, I proposed the following bipedal launch animation (Fig. 5). It combines the hind limb leap with the first flap of the large wings to provide the maximum thrust at takeoff. In the Habib proposal, you don’t get that wing flap until later in the cycle – maybe too late in the cycle. The quad launch also depends on directing the force of liftoff through the fragile free fingers. They were not strong enough for that, especialy not when there is a better option available using giant muscles in the chest and pelvis. That’s why the sacrum is so strong, to act as a fulcrum on that long, heavy lever!

FIgure 5. Dimorphodon take off (with the new small tail).

FIgure 5. Dimorphodon take off (with the new small tail).

So let’s get back
to Witton’s cover illustration (Fig. 6), which they tout as our contemporary view of Dimorphodon. I will note several inaccuracies (below). See figures 2 and 3 for accurate tracings.

Figure 6. Touted as the contemporary view of Dimorphodon, this Mark Witton illustration suffers from several fancies and inaccuracies.

Figure 6. Touted as the contemporary view of Dimorphodon, this Mark Witton illustration suffers from several fancies and inaccuracies.

  1. No Dimorphodon as this shape of skull.
  2. Needs a longer neck.
  3. Free fingers should be long and the unguals much larger.
  4. Wing appears to be too short with a too narrow wing tip chord.
  5. Witton wants to connect the trailing edge membrane from wing tip to ankle (or lateral toe), but look at the tremendous stretch in the membrane when that happens. Seems to be getting dangerously close to the narrow-at-the-elbow wing design of Zittel, Schaller and Peters, which they want to avoid.
  6. Ouch! This is a set of elongate toe bones with butt metatarsophalangeal joints – where Witton breaks them. This is not a calcar (a novel ossification on bat ankles which enters the uropatagium). One one side of these lateral toes the wing membrane attaches. On the other side the uroropatagium attaches. This is not shown in any fossil! Related taxa, from Langobardisaurus to Sharovipteryx, to Tanystropheus, with this same sort of elongate toe morphology, do not dislocate their bones this way. See Peters 2000 for a description that fits Rotodactylus tracks.
  7. No pterosaur has a uropatagium. This comes from a misinterpretation of Sordes. Pterosaur do have paired uropatagia.
  8. The tail is too large. On the BMNH 41212 fossil the traditionally overlooked tail is very small (Figs. 2, 7) This is in accord with related anurognathids. An unassociated tail has been attributed to Dimorphodon (Fig. 5) but it is robust and much longer. It probably belongs to a eudimorphodontid or campylognathoid. I”m surprised the tiny tail of Dimorphodon has gone unnoticed for so long. The specimen has been in English storage for over a hundred years. It was their responsibility for discovering this, but they chose instead to use their imaginations (Fig. 6).
  9. No tail vane is known for Dimorphodon. Tail vanes are found in pterosaurs like Campylognathoides and Rhamphorhynchus, both with a robust tail. Vestigial tails are unlikely to have had tail vanes.
FIgure 7. The tail of Dimorphodon (BMNH 41212 specimen). See figure 2 for reconstruction.

FIgure 7. The tail of Dimorphodon (BMNH 41212 specimen). See figure 2 for reconstruction.

I’m asking my Engllsh colleagues
|to step up their game and become more professional. Otherwise chaps from across the pond are going to continue pointing out the flaws in their thinking. I’m not going to say their approach is not scientific (as they say about my work), but when you forsake accuracy for artistry, you’re treading very close to that line.

Habib MB 2008. Comparative evidence for quadrupedal launch in pterosaurs. Zitteliana B28:159-166.
Hone DWE, Witton MP and Martill DM 2017.
New perspectives on pterosaur paleobiology in Hone DWE, Witton MP and Martill DM (eds) New Perspectives on Pterosaur Palaeobiology. Geological Society, London, Special Publications, 455, https://doi.org/10.1144/SP455.18
Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods 
Ichnos, 7: 11-41.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist 
Historical Biology 15: 277-301
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification.
Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605
Sangster S 2003. The anatomy, functional morphology and systematics of Dimorphodon macronyx (Diapsida: Pterosauria)..Unpublished PhD thesis, University of Cambridge.

“Pterosaurs” (2012) – same old problems – but gorgeous!

Veldmeijer, Witton and Nieuwland (2012) have a relatively new book out (Fig. 1, well… it just recently came to my attention), “Pterosaurs, Flying Contemporaries of the Dinosaurs.” And, like Witton (2013), this book presents the same problems in a gorgeous and easy-to-read fashion.

Figure 1. Pterosaurs, Flying Contemporaries by Veldmeijer et al. 2014.

Figure 1. Pterosaurs, Flying Contemporaries by Veldmeijer et al. 2014. Gorgeous artwork, unfortunately flawed by adherence to deep chord wing membranes. (See figure 4). This is akin to having dinosaurs continue to drag their tails in 2014.

Just a few pages will suffice for this review, but the whole book is available online here.

Problem # 1.
The authors nest pterosaurs between plesiosaurs and crocodiles (Fig. 2). Folks, I’m not making this up, but I think they are. Certainly this is the result of a dartboard throw, because no comprehensive phylogenetic analysis would ever produce these results. Rather, you can find the tested and verified nesting of pterosaurs here at the large reptile tree.

Figure 2. Veldmeijer et al. family tree nests pterosaurs between crocs and plesiosaurs, breaking all past traditions and barriers.

Figure 2. Veldmeijer et al. family tree nests pterosaurs between crocs and plesiosaurs, breaking all past traditions and barriers. Type enlarged for legibility. Color added.

Problem #2
What Bennett 2006 identified as a baby Germanodactylus, Veldmeijer et al. identify as a baby Pterodactylus (Fig 3). When we get back to reality, phylogenetic analysis nests it is as an adult of its own genus and clade, not even in the lineage of either more widely known genus. The little one is  SoS 4593 (formerly PTHE No. 29 III 1950, No. 9 of Wellnhofer (1970). If it looks like a little Scaphognathus, that’s because it is derived from little scaphognathids that were likewise reducing the tail. Bennett, Witton, Veldmeijer all have bought into the hypothesis of allometry (morphological change) during ontogeny, ignoring the proof for isometry during ontogeny in pterosaurs in Zhejiangopterus and embryo pterosaurs, like Pterodaustro.

Figure 3. Not a baby Pterodactylus, but a full grown tiny pterosaur the size of a sparrow.

Figure 3. Not a baby Pterodactylus, but a full grown tiny pterosaur the size of a sparrow. Insert added to put the two images to the same scale. One key to telling these two apart is in the feet. They had distinct phalangeal proportions unlikely to change during ontogeny. Plus, we have families of pterosaurs that demonstrate isometry during ontogeny. And these have been known for decades now. 

Problem #3
Sadly, like a droopy dinosaur tail, these pterosaurs (Fig. 4) continue to have bat-like, deep chord wing membranes, for which there is no evidence whatsoever. All the evidence proves that pterosaurs had a narrow chord wing membrane, like the added insets show.

Figure 4. Glamour shot of flying azhdarchids, unfortunately with deep chord wing membranes.

Figure 4. Glamour shot of flying azhdarchids, unfortunately with deep chord wing membranes. Insets offer corrections.

Problem #4
Finally, the authors offer a tracing from Wellnhofer 1991, of a quadrupedal walking pterosaur. I often like to place the trackmaker into the tracks (not in front of them  – Fig. 5) to see how carefully the artist has drawn the match. In the lower drawing, note the width of the track does not match the length. On another aspect going back to the original drawing, It’s best, when trying to match trackmakers to tracks, to elevate at least one or two and maybe three of the feet, leaving only one planted, not all four, as shown here (Fig. 5). When all four are implanted the animal has stopped. When two limbs are raised it is in the process of making tracks.

Figure 5. Above, standing/walking pterosaur traced from Wellnhofer 1991 by Veldmeijer et al. . Below, problems are illuminated. If you're going to have deep chord wing membranes, then you can't switch back to narrow chord ones when you want to. Rather, if you're going to be true to a configuration, then let the membranes droop when they're not pulled taut by the hind limbs.

Figure 5. Above, standing/walking pterosaur traced from Wellnhofer 1991 by Veldmeijer et al. . Below, problems are illuminated. If you’re going to have deep chord wing membranes, then you can’t switch back to narrow chord ones when you want to. Rather, if you’re going to be true to a configuration, then let the membranes droop when they’re not pulled taut by the hind limbs. And note the width of the track does not match the length.

It’s also valuable to animate the walk in order to work out all the problems. In figure 5, for instance, it is difficult to see how such a crouched over pterosaur could make such a long stride. It’s also difficult to imagine the order of limb placement.

Pterodactylus walk matched to tracks according to Peters

Figure 6. Click to animate. Plantigrade and quadrupedal Pterodactylus walk matched to tracks

If Veldmeijer et al. had just taken the time to match a real pterosaur to a real track they would have found what I found, that the only way to make it work is to elevate the back bone, as in this animated trackmaker that fits every step (Fig. 6).

Veldmeijer AJ, Witton M and Nieuwland I 2012. Pterosaurs, flying contemporaries of the dinosaurs. online here.

Mark Witton’s “Pterosaurs” – a book review part 1

Dr. Mark Witton is fantastic artist and devotee of pterosaurs. He has a new book called Pterosaurs (with an Amazon.com preview). I’ve ordered the book and will make an in depth report after it arrives. The following is based on the online preview of chapter 1. Witton’s writing style is entertaining and engaging. The book should have popular appeal on that level.

The cover portrays a magnificent crested Nyctosaurus at sunrise or sunset. Gorgeous!

Then things tumble.

Witton’s Table of Contents shows an embryo Pterodaustro with a very short rostrum, unlike any Pterodaustro I’ve ever seen. And I’ve seen the embryo. The rostrum extends nearly the entire length of the egg. An agreement with Laura Codorniú prohibits me from publishing the image until she does, but the reconstruction of the long-beaked embryo Pterodaustro is based on that tracing. As we learned earlier, pterosaurs grew isometrically, resembling their parents on hatching.

Witton’s Rhamphorhynchus image on page 2 portrays the infamous cruro/uropatagium, a membrane spanning the hind limbs and not including the tail. The image also includes the infamous deep chord wing membrane, for which there is no evidence whatsoever as the Sordes situation was falsified. Witton’s two Rhamphs also have much shorter wings than any Rhamphorhynchus I’ve ever seen. One of Witton’s wonders has brought its wrists (carpals) in close to the base of the neck, which is novel, at least, but kills the tension on the extensor tendon that keeps the wing membrane aerodynamic. As in birds, when the elbow flexes, the wing folds. Having the wings fold in flight isn’t bad. Birds do it all the time for a brief low drag rest. At least the feet are properly positioned in Wittons’ illustration.

Page 3 portrays several dozen pterosaurs doing the forelimb leap that is such a travesty and fantasy that I slap my head every time I see it again and again. It has become firmly entrenched. Gadzooks@!# what is the ptero-world coming to?

Page 4 has a fine picture of Pterodactylus antiquus, the first pterosaur known to science, with a big round head crest. Not quite ready to buy into that one quite yet. Some Pterodactylus did have a crest, but not that one.

Page 12 portrays a hypothetic pterosaur ancestor. It looks like Peteinosaurus with a short digit 4 leaping from a branch (using muscular hind limbs). The caption reads, “The fossil record has yet to reveal an “intermediate” between fully formed pterosaurs and possible ancestors, meaning we can only speculate on their anatomy and appearance.” And once again, pterosaur professors are casting a blind eye toward the hard evidence presented in the large reptile tree where dozens of ancestors are lined up. As you’ll recall, ludicrous as it sounds, we can even put turtles up as the closest known sisters to pterosaurs if we delete all the other sisters and candidates from the new Lepidosauromorpha, as demonstrated here. This just proves that pterosaur workers are actively avoiding the issue and the answer. But, I have to say, it’s a beautiful and evocative image that Witton has created, wrong though it may be.

Page 16 portrays three purported pterosaur ancestor/sisters, Sharovipteryx, Euparkeria and Scleromochlus. Witton calls Sharovipteryx an archosauromorph protorosaur, when it is neither. It is a fenestrasaur tritosaur lepidosaur, as we learned earlier. Euparkeria is closest to erythrosuchids, about as far from pterosaurs as one could imagine. Scleromochlus, shown hopping in Witton’s illustration with a dino quadrate leaning the wrong way, is a basal crocodylomorph. Witton strongly leans toward the “pterosaurs are ornithodires” direction despite the tiny hands and lack of pedal digit 5 in Scleromochlus.

Witton takes aim at my placing pterosaurs within the Squamata as the most unlikely hypothesis currently under consideration. See a recent post on this here. Witton writes, “There seems little similarity between the skulls of pterosaurs and the highly modified, mobile skulls of squamates or any similarity between the trunk and limb skeletons of each group.” Well, frequent readers will know that pterosaurs are tritosaur lepidosaurs, an outgroup clade to the two that make up the Squamata, the Iguania and the Scleroglossa. Pterosaurs are neither of these. Tritosaurs do not have the mobile skulls found in some squamates. They also don’t have the fused tarsals of squamates. They are distinct. Witton has whitewashed the tritosaur fenestrasaur hypothesis with this “red herring,” while virtually ignoring the fenestrasaurs, following in the less than noble footsteps of our colleague Dr. David Hone, whose exploits you can read about here. In chapter one, at least, Witton avoids any discussion of the pteroid and prepubis in Cosesaurus and other fenestrasaurs. Why should he ignore these key and readily observable traits? Dr. Pierre Ellenberger saw them first without recognizing their significance.

Page 17 Witton then discusses the possible protorosaur origins of pterosaurs, pointing to the shared trait of an elongated neck and forgetting the not-so-elongated neck of the basalmost  pterosaur, MPUM6009.  Witton points up the “fact” that protorosaurs lack an antorbital fenestra, but recent finds show that two protorosaurs had such a fenestra by virtue of convergence (really a side issue of little consequence). Witton finishes with protorosaurs by noting the body shapes are not at all pterosaurian, which is true.

Witton invites a closer look at Sharovipteryx and notices similarities to pterosaurs in the hind limbs and their membranes, but notes, “It’s hard to find other features that reliably link this animals with pterosaurs.” He may not have looked at the actual specimen as I have. Evidently he did not notice the ilium was anteriorly elongated, prepubes were present, more than five sacrals were present, the tail was attenuated with parallel chevrons, the bones were hollow, the feet have the same morphology as pterosaurs with a short metatarsal 5 and an elongated and robust p5.1 as obvious and compelling similarities. Once again, the blind eye rules. Witton reports that the Sharovipteryx skull lacks an antorbital fenestra and the foot is unlike that of any pterosaur. Where does he get his information? Certainly not from any sort of direct observation or adherence to the literature. Of course he doesn’t back up any of this with evidence. Witton concludes by noting that gliding with hind limbs is unique, failing to find parallels in Microraptor and the uropatagia of fenestrasaurs including pterosaurs. Sharovipteryx had fore limbs. Witton just doesn’t know or doesn’t show what they look like. But you can see them here.

Page 18 Witton prefers the archosauriform ancestry hypothesis due to the shared features of an antorbital fenestra and reduced bone counts in the fifth pedal digit, perforated lower jaws, and “many other anatomical similarities.” Really? Witton equates an evaporating pedal digit 5 in archosauriforms with the robust element in pterosaurs (and, of course he doesn’t count the ungual on the pterosaur digit). A robust pedal digit 5 is also found in Huehuecuetzpalli and all the tritosaur lepidosaurs that followed (except Macrocnemus and the drepanosaurs). Why doesn’t Witton consider these and put some study into them? The antorbital fenstra of archosauriforms is always (except for proterosuchians) surrounded by a fossa, a trait lacking in any pterosaurs.

Witton also prefers archosaurs as pterosaur sisters, and, in particular, Scleromochlus, despite the tiny hands that were, ironically, used to rule out Sharovipteryx. Evidently Witton prefers to have it both ways, so long as he stays within tradition. Witton lists fusion of the two proximal ankle bones to the shin (which does not occur in pterosaurs), reduction of the fibula (also in tritosaurs), the structure of the foot (actually more like that of tritosaur lizards like Cosesaurus, which retain an elongated pedal digit 5, which archosaurs lack), “several limb and hip proportions” (can Witton get even more vague here?) and the lack of bony scales along the back (then why is he ignoring those on Scleromochlus and Scutellosaurus).

Witton notes the shield-like pelves were different than in dinosaurs, but defends that by saying, “This may not be surprising, however, given, that pterosaur hindlinmbs were, uniquely among ornithodirans, used to support the wing in flight.” Utter rubbish!!! on the face of it and not pertinent to any phylogenetic discussion. You take the traits as they are and you let the computer decide where the taxa belong most parsimoniously. The “why” question or reason is never in play. By the way, similar pelves to pterosaurs can be found in fenestrasaurs, but these are ignored by Witton.

Witton writes, “arguments that basal pterosaurs were bipedal and digitigrade may be flawed” because basal ornithodires (aka: Asilisauruswhich bears no resemblance whatsoever to pterosaurs) were quadrupeds. This is far-reaching and totally bogus. I would be ashamed and would expect heavy chastisement having made such a comparison, especially after promoting bipedal Scleromochlus as a potential ancestor. But then Witton tops that bungle of reasoning by saying that Scleromochlus is “suspected of hopping about on plantigrade feet.” More fantasy! Few creatures, other than deer and horses, have feet more obviously digitigrade than Scleromochlus. Witton also ignores the known bipedal pterosaur footprints  (more here, here and more info here).

Page 21 Witton prefers an imagined hypothetical ancestor to a real one, and it glides from trees. Of course, this does nothing to explain the origin of flapping (because no gliders flap, unless they started off as flappers). Witton ascribes the mobility and length of the fifth toe to its use as a stabilizing tool, ignoring the fact that most tritosaurs from Tanystropheus to Sharovipteryx, have such a fifth toe, thus it cannot be developed for flight. Witton reports that the fifth toe, which is lateral, elongates to frame the medial membrane, which should strike you as odd and implausible. In reality the fifth toe is not connected to a membrane, except in Sharovipteryx, and each membrane trails each hind limb. They don’t cross to connect with each other.

Page 22 Witton reports that the hind limbs rotate out sideways to create efficient airfoils, but even that is fraught with error. One: Archosaurs can’t do this with their erect femurs. Two: Basal pterosaurs can’t do this either with their erect femurs. Raising the hind limbs to the horizon happens in later, more derived pterosaurs with a more sprawling femur.

Witton reports that during the evolution of pterosaurs that the fourth finger became so enlarged and unwieldy that it needed to be stowed away when grounded. We can all stow away our fingers by pressing them against our palms, but Witton ignores this. He also ignores the axial rotation of metacarpal 4 so that digit flexion puts digit 4 along the posterior rim of the hand, not the palmar side any longer. Witton reports ungual 4 was missing, since it was no longer necessary. We’ve seen so many several cases of ungual 4 present on pterosaurs that it needs to be considered universal.

Witton adds fibers to wing membranes as they need to be more sophisticated in their unsupported regions, ignoring that Cosesaurus had trailing fibers before it had wing membranes (Ellenberger 1993, Peters 2009).

With regard to flapping, our expert Dr. Witton reports, “At some point, manipulation of these wings in the vertical plane produced flapping, and self-propelled flight was achieved.” Gee, he makes it sound almost as if it was that easy. At ReptileEvolution.com and the PterosaurHeresies blog you learned the exact steps the exact taxa took to achieve flapping prior to the development of wings in pterosaurs, paralleling that same development in birds. So if Witton’s book leaves you unsatisfied and yearning for real answers, come see these websites and blogs.

Witton ascribes the development of flight muscles and bones to the ability of quadrupedal pterosaur ancestors to chiefly employ the forelimbs during leaps. He sort of leaves the larger hips and thighs out of the equation, evidently incapable of creating all the power necessary for a leap and leaving the unused arms in this bipedal model to do something else, like flap as a secondary sexual trait.

Dr. Witton does take the brave leap of including my published works in his reference list, something Dr. Unwin did not do in his less recent pterosaur book.

Let’s face it
If Dr. Witton does not even know what pterosaurs are (which he has acknowledged in his book), he has no business acting as an expert on pterosaurs and writing books about them. Unfortunately this is an acceptable trend continued by Dr. Unwin from Dr. Peter Wellnhofer. In chapter one Witton has already published too many errors. It’s too late in the game to fold ones’ hands and politely tell your readers, “Good question… we really don’t know. It’s one of the mysteries of paleontology.” There’s something called phylogenetic analysis that is guaranteed to give you an answer when you’re looking for an ancestor. However, you’ll have to include at least a few of the right taxa (among the tritosaurs in this case), to get close to the right answer. If you’re looking for the ancestors of pterosaurs, they’re right here in one place.

We’ll look at other Witton chapters in the future. But this one on pterosaur origins really irks me. It’s rather embarrassing that this sort of crap (a complete avoidance of certain data) is still being circulated. But I _do_ love the artwork.

Ellenberger P 1993. Cosesaurus aviceps . Vertébré aviforme du Trias Moyen de Catalogne. Étude descriptive et comparative. Mémoire Avec le concours de l’École Pratique des Hautes Etudes. Laboratorie de Paléontologie des Vertébrés. Univ. Sci. Tech. Languedoc, Montpellier (France). Pp. 1-664.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29: 1327-1330.
Witton M. 2013. Pterosaurs. Princeton University Press. 291 pages.