First African pterosaur trackway (manus only)

FIgure 1. From Masrour et al. 2017, manus only pterosaur tracks. They are BIG!

FIgure 1. From Masrour et al. 2017, manus only pterosaur tracks. They are BIG! Again I will note, only lepidosaurs can bend their lateral metacarpophalangeal joints within the palmar plane at right angles to the others, producing posteriorly oriented manual digit 3.

Masour et al. 2017
bring us new manus only Late Cretaceous azhdarchid tracks. They report, “The site contains only manus tracks, which can be explained as a result of erosion of pes prints.” They assume that the pterosaur fingers pressed deeper, carrying more weight on the forelimbs. Of course, this is a bogus explanation. No tetrapods do this. Pterosaurs put LESS weight on their tiny fragile fingers. They used their hands like skiers used ski poles.

FIgure 2. From Masrour et al. 2017, model of the trackmaker of the manus only tracks.

FIgure 2. From Masrour et al. 2017, model of the trackmaker of the manus only tracks erroneously attributed to Bennett 1997, who drew Pterodactylus, not this generalized azhdarchid.

There is another explanation for manus only tracks
called floating and poling, but that hypothesis was dismissed by the authors.

Masrour et al. dismiss the possibility of floating
by referencing Hone and Henderston 2014 in which simulations of the buoyancy of poorly constructed pterosaurs made using computers indicate that these reptiles had no ability to float well in water. This hypothesis was dismantled earlier here. In addition, Hone’s track record is not good. Neither is Henderson’s, who does not seem to care about using accurate skeletal reconstructions.

More importantly,
if Hone and Henderson put forth an anti-floating hypothesis no one (and certainly no scientist) should simply believe in it. This is Science. Others, like Masrour et al., should TEST hypotheses for validity, as was done here. Instead Masrour et al. put forth a hypothesis in which pes tracks were selectively erased over time, which seems preposterous and unnatural. This sort of selective erasure has never been observed in Nature.

Figure 1. The azhdarchid pterosaur Quetzalcoatlus floating and poling producing manus only tracks.

Figure 3. The azhdarchid pterosaur Quetzalcoatlus floating and poling producing manus only tracks. Remember the skull is as light as a paper sculpture.

Scientists fail
when they blindly follow bad hypotheses, just because they are published. Nodding journalists repeat what they read, whether right or wrong. Scientists test whenever they can.

Figure 5. Tapejara poling while floating, producing manus-only tracks, all to scale.

Figure 4. Tapejara poling while floating, producing manus-only tracks, all to scale. Remember the skull is as light as a paper sculpture.

Don’t believe in Henderson cartoons
(Fig. 5). Test with accurate representatives of skeletons IFig. 4).

Computational models of two pterosaurs from Hone and Henderson 2013. Note how both have trouble keeping their nose out of the water. Henderson's models have shown their limitations in earlier papers.

Figure 5. Computational models of two pterosaurs from Hone and Henderson 2013/2014. Note how both have trouble keeping their nose out of the water. Henderson’s models have shown their limitations in earlier papers.

When you don’t use cartoons for data
then you have a much better chance of figuring out how Nature did things.

Figure 4. Two configurations for Rhamphorhynchus. Because the wings act like pontoons, the torso and skull can be rotated relative to the wings to adopt a variety of floating configurations. Also note the large webbed feet, preserved in the darkling specimen. The tail can be elevated at its base.

Figure 6. Two configurations for Rhamphorhynchus. Because the wings act like pontoons, the torso and skull can be rotated relative to the wings to adopt a variety of floating configurations. Also note the large webbed feet, preserved in the darkling specimen. The tail can be elevated at its base.


Thank you for your continuing interest.
After over 2000 blog posts the origin of bats continues to be the number one blog post visited week after week, with totals equalling the sum of the next five topics of interest. That’s where the curiosity of the public is right now.

References
Hone DWE, Henderson DM 2014. The posture of floating pterosaurs: Ecological implications for inhabiting marine and freshwater habitats. Palaeogeography, Palaeoclimatology, Palaeoecology 394:89–98.
Masrour M et al. (4 other authors) 2017. 
Anza palaeoichnological site. Late Cretaceous. Morocco. Part I. The first African pterosaur trackway (manus only). Journal of African Earth Sciences (in press) 1–10.

 

https://pterosaurheresies.wordpress.com/2013/12/06/pterosaurs-were-unlikely-floaters-hone-and-henderson-2013/

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Earliest Cretaceous pterosaur tracks from Spain

Pascual-Arribas  and Hernández-Medrano 2016
describe new pterosaur ichnites from La Muela, near Soria, Spain.

From the abstract
“Pterosaurs tracks in the Cameros basin are plentiful and assorted. This fact has allowed to define several Pteraichnus ichnospecies and moreover to distinguish other morphotypes. The study of the new tracksite of La Muela (Soria, Spain) describes Pteraichnus cf. stokesi ichnites that is an unknown ichnospecies until now and that confirms the wide diversity of this type of tracks in the Cameros Basin. Their characteristics correspond to the ones of the Upper Jurassic track sites of United States. Similar tracks have already been described in other tracksites, both inside and outside the Iberian Peninsula during the Upper Jurassic-Lower Cretaceous transit. Because of their shape and morphometrical characteristics they can be related to the pterosaurs of the Archaeopterodactyloidea clade. The analysis of this ichnogenus indicates the need for a deep review because encompasses ichnites with a big variety of shapes and morphometric characteristics.”

Figure 1. La Muela pterosaur manus and pes tracks, plus tracing and sister ichnotaxa among basalmost ctenochasmatids.

Figure 1. La Muela pterosaur manus and pes tracks, plus tracing and sister ichnotaxa among basalmost ctenochasmatids. Note the extreme length of manus digit 1. This may result from secondary and further impressions during locomotion. Such an extension is no typical. Ctenochasmatids have shorter fingers and claws.

By adding the traits of the La Muela track
to the large pterosaur tree (LPT, 233 taxa) it nested precisely between stem ctenochasmatids and basalmost ctenochasmatids.

Why guess when a large database already exists?
That’s why I published the pterosaur pes catalog with Ichnos in 2011.

Those manus tracks are rather typical for pterosaurs.
Impossible for archosaurs. Typical for lepidosaurs, which have looser metacarpophalanageal joints.

Pascual-Arribas and Hernandez-Medrano
draw triangles, Y-shapes and rectangles around Ctenochasma, azhdarchid and Pterodaustro tracks. Since the triangle and rectangle taxa are sisters, this nearly arbitrary geometrical description is of little phylogenetic use. Ctenochasmatids can spread and contrast their metatarsals, so they can change their pes from one ‘shape’ to another.

A second paper on Spanish ptero tracks
by Hernández-Medrano et al. 2017 describe more tracks. In the first paper, some pterosaur pedes were correctly attributed to Peters 2011. The same illustrations in the second paper were attributed to the authors of the first paper. :  )

References
Hernández-Medrano N, Pascual-Arribas C and Perez-Lorente F 2017. First pterosaur footprints from the Tera Group (Tithonian–Berriasian) Cameros Basin, Spain. Journal of Iberian Geology DOI 10.1007/s41513-017-0020-8. (in English)
Pascual-Arribas C and Hernández-Medrano N 2016. Huellas de Pteraichnus en La Muela (Soria, España): consideraciones sobre el icnogénero y sobre la diversidad de huellas de pterosaurios en la Cuenca de Cameros. (Pteraichnus tracks in La Muela (Soria, Spain): considerations on the ichnogenus and diversity of pterosaur tracks in the Cameros Basin.) Revisita de la Sociedad Geologica de España 29(2):89–105. (in Spanish)
Peters D 2011. A catalog of pterosaur pedes for trackmaker identification. Ichnos, 18: 114–141.

 

U of Leicester is seeking a pterosaur tracker.

Don’t let your academic ‘foot’ get caught in this trap.

This post arose
from an online want ad for a student pterosaur tracker posted by Dr. Dave Unwin and his team (see below) at the University of Leicester, England. Earlier we looked at a similar ad seeking a student who could find evidence for the invalidated pterosaur forelimb launch hypothesis. This new ad appears to be similarly doomed by conclusions drawn before the first student applies for this solicitation.

What is it about the English paleontology system
that promotes single-minded and undocumented thinking when it comes to pterosaurs? We’ve seen hyper-biased papers from Hone and Benton (2007, 2009), hyper-biased critiques from Dr. Naish, and pterosaur books authored by Dr. Unwin and Dr. Witton that ignored pertinent studies. Several English PhDs also supported the invalidated and unsupported anterior pteroid hypothesis. All seem to hold that pterosaurs are archosaurs, despite a complete lack of evidence and outgroups for that assertion and plenty of evidence for a lepidosaur tritosaur fenestrasaur origin, that they systematically ignore. All seem to support the invalidated bat-wing, deep-chord pterosaur wing fantasy that finds no evidence in the fossil record. This group holds to the outmoded notion that sparrow- and hummngbird-sized Solnhofen pterosaurs are juveniles, which is easy to dismiss on several grounds. There may be a few more stumble blocks I’ve failed to list here, like isometric growth in pterosaurs.

If you are a student of pterosaurs,
try to avoid the influence of this antiquated and conjoined bastion of pterosaur workers. The text of their want ad demonstrates that, like an earlier solicitation, you will have to arrive at their odd conclusions and support their invalid hypotheses. Rather than that, keep to independent thinking. It may prove to be key to understanding pterosaurs. Follow the data. I did so in my spare time. You can do it, too.

Here’s the ad
(see below in italic blue) with notes added [in brackets[.

Title:
The tracks of pterosaurs, and their implications for pterosaur palaeoecology and evolution 

Supervisory team
David Unwin, School of Museum Studies, University of Leicester (dmu1@le.ac.uk)

Mark Purnell, Department of Geology, University of Leicester (map2@le.ac.uk)
Richard Butler, School of Geography, Earth & Environmental Sciences, University of Birmingham
Peter Falkingham, School of Natural Sciences and Psychology, Liverpool John Moores University
Brent Breithaupt, 812 S. 13th St., Laramie, WY 82070 USA

From their online ad:
“Pterosaurs, Mesozoic flying reptiles, were long considered to have been almost exclusively confined to aerial niches, with only limited mobility when on the ground (Unwin, 2005). [1] Two lines of evidence have challenged this view. (1) A rapidly accumulating and increasingly diverse pterosaur track record (pteraichnites) that spans more than 80 million years. (2) Digital modelling, based on skeletal remains and tracks, of pterosaur’s terrestrial locomotory abilities. These studies show that pterosaurs used a flat-footed, four-legged, but nevertheless highly efficient, stance and gait. [2] They have also uncovered some unexpected behaviours, such as a quadrupedal launch, [3] that point to a far more effective ability to take-off and land than previously suspected. These new findings suggest that pterosaurs played a much bigger role in Mesozoic terrestrial communities than previously realised (Witton, 2013), but the extent and evolutionary significance of this phenomenon remains unclear and controversial. [4]

Notes

  1. This is only one of Dr. Unwin’s bogus hypotheses based on his invalidated idea that the hind limbs of basal pterosaurs were encumbered by a uroptagium that bound them together and bat-like deep-chord wings tied the legs to the wings. No pterosaur tracks show limited mobility. No fossil evidence documents either membrane structure.
  2. Ignored studies (Peters 2000a, 2010, 2011) and many pterosaur tracks indicate that plantigrade quadrupedal pterosaurs are restricted to certain clades, typically while beach combing, and that all pterosaurs were fully capable of bipedal locomotion and launch. Some pterosaurs were digitigrade, as demonstrated by their tracks and their parallel interphalangeal lines (Peters 2000. 2011).
  3. Bogus. No evidence in the track record. Click here, here and here for counter evidence.
  4. A bigger role? How do you answer that question?

“This project will use a multidisciplinary approach to reassess the contribution of pterosaurs to Mesozoic continental biotas and their impact on co-evolving groups such as early birds (Benson et al, 2014). New techniques including photogrammetric ichnology will form part of the first systematic analysis of the pterosaur track record. [1] This work will generate a range of data sets that capture fine detail of prints and tracks that can be combined with contextual data including sedimentology, stratigraphy and associated ichnological and body fossil evidence.

Notes

  1. The Unwin team is ignoring the actual first systematic analysis of the pterosaur track record, published in Ichnos five years ago (Peters 2011). Perhaps they ignore it because that ‘track record’ documented bipedalism, digitigrady and other ‘unapproved’ pterosaur activities and configurations.

“These data sets will underpin three complementary strands of the PhD: (1) reconstruction of the locomotory styles and abilities of pterosaurs (stance, gait, speed, take-of and landing modes) based on key sites in the USA and Europe. (2) The first comprehensive integration of the ichnological and body fossil record of pterosaurs via 3D digitisation of prints and well preserved skeletal remains. (3) Identification and reconstruction of specific behaviours (e.g. feeding, flocking) set within current interpretations of the palaeoenvironments in which they occurred.

Results of these three studies will be combined with data on the relationships and temporal and biogeographic distribution of pterosaurs to determine the extent to which they contributed to Mesozoic terrestrial biotas and influenced the evolution of contemporaneous groups such as birds.

 

Standing Pteranodon

Figure 1. Bipedal and digitigrade Pteranodon. Both are unapproved by the Leicester team but supported by evidence found in ignored literature.

Methodology

“New approaches to collecting and interpreting prints and tracks including photogrammetry, pioneered by Breithaupt (e.g. Lockely et al., 2016) will be used to generate high fidelity 3D digital data sets based on key sites in the USA (Wyoming), France (Crayssac) and Spain (Asturias) that contain multiple individuals and exceptionally high quality impressions (Unwin, 2005; Witton, 2013).

Identification of track-makers will take advantage of our rapidly expanding knowledge of pterosaur skeletal anatomy and the possibility of highly accurate comparisons between digitised sets of tracks and 3D skeletal elements of the hand and foot. [1] This approach will be located within a well established phylogenetic framework developed by Unwin and others. [2] Digital models have been shown to be highly effective at constraining likely stance, gait, velocity and manoeuvrability for extinct taxa (Falkingham and Gatesy, 2014) and will be applied here to both ichnological and skeletal data. The reconstruction of behaviours, palaeoenvironments and the evolutionary history of pterosaur terrestrial palaeoecology, supervised by Butler, will use quantitative approaches set within a phylogenetic framework. [3]

Notes

  1. This has already been done here and in Ichnos (Peters 2011), but testing, comparisons, confirmations and refutations are always welcome.
  2. Okay, if you’re going to do this, remember Unwin’s cladogram deletes all the small and tiny Solnhofen pterosaurs that form transitions between larger long-tails and larger short tails. He holds that Darwinopterus is the transitional taxon linking long-tails to short-tails, rather than an evolutionary dead end as shown here, along with several other odd phylogenetic nestings.
  3. Play by their rules and you will get their PhD. But should you play by their rules? They would love it if you could support their conclusions. Funny that they want an inexperienced and beholding student to do the work they are much better qualified to do, but won’t do. Also odd that they are not open to any and all solutions the data may deliver. After all, reporting conclusions AFTER the data comes in IS the scientific method.

Training and Skills

“Students will benefit from 45 days training throughout their PhD including a 10 day placement. Initially, students will be trained as a single cohort on research methods and core skills. Training will progress to master classes, specific to projects and themes. Specialist training will include identification and interpretation of pterosaur tracks and skeletal anatomy, supervised by Unwin, photogrammetry as applied to palaeoichnology, supervised by Breithaupt and Butler, and analysis of locomotion, supervised by Falkingham. The student will also receive training, supervised by Butler, in data base construction with a particular emphasis on the statistical analysis of palaeontological data.

Timeline

“Year 1: Familiarisation with literature, existing datasets and palaeoichnological techniques including photogrammetry. Fieldwork in the USA to collect pterosaur track data. Analysis of these data. Presentation at PalAss (UK) and SVPCA (UK).

Year 2: Fieldwork in Spain and France to collect pterosaur track data. Continued analysis of all track data and integration with body fossil record. Analysis of pterosaur locomotory styles. Publication and presentation at SVPCA (UK), EAVP (Europe).

Year 3: Synthesis of results on locomotory abilities, behaviours and palaenvironments. Develop evolutionary history of pterosaurs in terrestrial environments. Publication and presentation at SVPCA (UK), SVP (USA). Write and submit thesis. [9]

Notes

  1. Having already done much of the work they are asking, I wonder… would I be interested in getting a PhD from the Leicester team? No. I can’t bend that far. But seriously, GOOD LUCK to that candidate, whoever you may be. Negotiate for the scientific method before you sign on.

Partners and collaboration (including CASE)

“Dr Unwin has 30+ years experience of research on pterosaurs, holds extended datasets on pterosaur skeletal anatomy, and palaeoichnology and has access to key specimens that will be studied during this project. Prof Purnell has expertise in analysis of 3D surface datasets in the context of vertebrate ecology and function. Dr Falkingham has worked on fossil footprints for over a decade, using computational techniques including simulation (FEA, DEM, MBD) and digitization (laser scanning, photogrammetry) to study locomotion and footprint formation. Dr Butler has published widely on fossil reptiles, including pterosaurs, and has extensive experience in the application of quantitative approaches to analysis of palaeontological data. Dr Breithaupt has pioneered the development of photogrammetric ichnology, including its application to pterosaur tracks.

Further Details

Ideally, applicants should have a first degree in the geological or biological sciences and an aptitude for quantitative analysis. At Leicester you will join a dynamic group of researchers, PhD and Masters students developing novel approaches to the analysis of palaeoecology and evolution in fossil vertebrates.

Figure 1. Cartoon favorite Elmer Fudd tracking Bugs Bunny... or are those bipedal Pteraichnus tracks?

Figure 2. Cartoon favorite Elmer Fudd tracking Bugs Bunny… or are those bipedal Pteraichnus tracks?

Contact

D.M. Unwin
School of Museum Studies, University of Leicester,
19 University Road, Leicester LE1 7RF
Tel: +44 116 252 3946

Further reading

Benson, R.B.J. et al. 2014. Competition and constraint drove Cope’s rule in the evolution of giant flying reptiles. Nature Communications, 5, 3567, doi: 10.1038/ncomms4567.
Falkingham, P.L. & Gatesy S.M. 2014. The birth of a dinosaur footprint. Proc. Nat. Acad. Sci., 111, 18279-18284.
Lockley, M.G. et al. 2016. Theropod courtship: large scale physical evidence of display arenas and avian-like scrape ceremony behaviour by Cretaceous dinosaurs. Nature: Scientific Reports, 6, nb 18952, doi:10.1038/srep18952.
Unwin, D.M. 2005. The Pterosaurs from Deep Time. Pi Press, New York, 347pp.
Witton, M.P. 2013. Pterosaurs: natural history, evolution, anatomy. Princeton University Press. 291pp.”

Forbidden and ignored references
Notably absent from the above published text and references are the following pertinent and peer-reviewed academic papers that do not support the hypotheses the prospective PhD candidate will have to labor under and support, regardless of the data and results.

Peters D 2000a. Description and interpretation of interphalangeal lines in tetrapods
Ichnos, 7: 11-41
Peters D 2000b. A redescription of four prolacertiform genera and implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106: 293-336.
Peters D 2002. A new model for the evolution of the pterosaur wing – with a twist. Historical Biology 15: 277-301.
Peters D 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 2007.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29(4):1327–1330.
Peters D 2010. In defence of parallel interphalangeal lines. Historical Biology iFirst article, 2010, 1–6.
Peters D 2011. A catalog of pterosaur pedes for trackmaker identification. Ichnos 18(2):114-141.

For abstracts of the above click here.

SVP 11 Pterosaur pelvic morphology

Frigot 2015 
provides general information about pterosaur pelves using principal component analysis, similar to that of Bennett 1995, 1996. I hope it works out better for Ms. Frigot.

From the abstract
“Pterosaurs have modified the basic triradiate amniote pelvis, extending the ilium into elongate processes both anterior and posterior to the acetabulum. While pterosaurs are now generally accepted to move quadrupedally on the ground*, many hypotheses exist regarding the diversity of gaits and terrains exploited across Pterosauria and how this may be correlated with the shifts in body plan found at the base of the monofenestratans and of the pterodactyloids. Early attempts to bring comparative anatomy to bear upon the topic have been largely descriptive of pelvic shape across the clade. I attempt to rectify this by providing a geometric morphometric analysis of a phylogenetically diverse sample of pterosaur pelves. Using landmark-based methods, shape was captured at the bone margins and acetabulum, with a view to capturing surfaces available for muscle attachment. These landmarks were analyzed using principal components analysis (PCA). Principal components 1 and 2 distinguish well between genera, reducing possible concerns over the role of taphonomy and ontogeny in determining shape**. It is not apparent whether the lack of a phylogenetic trend across shape space is due to small sample size or a high degree of evolutionary plasticity, highlighting the need for a greater sample size. However, with this support for a biological signal in the data, subsequent steps can be made that focus on biomechanical and locomotor analyses using detailed anatomical observations. We can then try to identify how pelvic disparity might have led to a diversity of locomotor styles in this most unique taxon.”***

*That’s traditional thinking. Many pterosaur tracks indicate bipedal locomotion.
**Ontogeny does not change pelvis shape because pterosaurs grew isometrically.
***So, sorry… no taxa or conclusions here.

References
Frigot RA 2015. The pterosaurian pelvis. An anatomical view of morphological disparity and implications for for locomotor evolution.

Stalking or wading azhdarchids (part 3)

Witton and Naish (2013) proposed a terrestrial stalking mode of operation for azhdarchid pterosaurs (Fig. 1). We looked at various aspects of that earlier here and here. Today, a few more details need to be considered.

Figure 1. Click to enlarge. On right from Witton and Naish 2013. On left reconstruction from Cai and Wei 1994 of Zhejiangopterus.

Figure 1. Click to enlarge. On right from Witton and Naish 2013. On left reconstruction based on data from Cai and Wei 1994 of Zhejiangopterus. Compare right stalking image with figure 3 wading image. Consider the great weight of that big skull on the end of that long skinny neck supported by those tiny fingers. All those problems are solved when wading (Fig. 3).

The following notes are retrieved from the boxed captions surrounding the Witton and Naish image (Fig. 1), which you can enlarge to read. 1. Reclined occipital face – Head perpetually angled towards ground when neck is lowered. – True of all wading pterosaurs and most pterosaurs in general. 2. Neck anatomy and arthrology – Long neck reduces effort to produce large movements; range of motion allows easy access to the ground. – True of all wading pterosaurs and most pterosaurs in general. 3. Skull shape and hypertrophied jaw tips – Skull morphology most similar to terrestrial feeding generalists, such as ground hornbills and modern storks; jaw elongation reduces neck action required to reach ground level – True of all wading pterosaurs and most pterosaurs in general.

Figure 3b. Zhejiangopterus fingers. Witton and Naish want you to believe that these three fragile fingers on three spaghetti-thin metacarpals are suitable weight-bearing bones - OR that mc4 is a weight-bearing bone. Neither is true. Metacarpal 4 NEVER makes an impression. The wing finger NEVER makes an impression. They were both held above the substrate in ALL pterosaurs.

Figure 2. Zhejiangopterus fingers. On left based on Cai and Wei 1994. On the right, according to Witton and Naish who want you to believe that these three fragile fingers on three spaghetti-thin metacarpals are suitable weight-bearing bones – OR that mc4 is a weight-bearing bone. Neither is true. Metacarpal 4 NEVER makes an impression. The wing finger NEVER makes an impression. They were both held above the substrate in ALL pterosaurs. The Witton Naish metacarpal is over rotated in order to allow fingers 1-3 to hyper-extend laterally, but that means the wing finger also opens laterally, not in the plane of the wing! Their mc 1-3 are pasted against mc 4, dorsal sides to dorsal side following the false Bennett model. Their fingers don’t match ichnites.

4a. Large coracoid flanges: distally displaced crests. Enlarged anchorage and increased lever arm for flight muscle; powerful takeoff ability. – Actually azhdarchids have relatively small pectoral complexes and small humeri. Witton and Naish employed a juvenile sample for their humerus. 4b. Enlarged medial wing length, decreased wing finger length. Increased forelimb stride; enlarged medial wing region and greatest lift; reduced risk of snagging wingtips on vegetation. – This is also true of all wading bottom feeders, and most pterodactyloid-grade pterosaurs in general. Also note that these traits are present in tiny Solnhofen pterosaurs (Fig. 3). Decreased wing finger length reaches a nadir in JME SOS 2482, a flightless pterosaur with a big belly and definitely NOT a stalker of terrestrial vertebrates.  5. Robust digit bones. Adaptations to weight bearing. – Obviously not true. The free fingers of Zhejiangopterus are both small and gracile and have no obvious adaptation to weight bearing. So, why are they bearing nearly all the weight of Zhejiangopterus (Fig. 1) in the Witton and Naish reconstruction? Instead, think of pterosaur forelimbs like ski poles, good for steadying (Fig. 3), especially while feeding in moving waters (Fig. 4. All weight bearing runs through the hind limb. Here is a Zhejiangopterus matched to tracks (Fig. 3). Witton and Naish make no effort to match a manus and pes to the tracks they use. 

Figure 2. The large azhdarchid pterosaur, Zhejiangppterus. is shown walking over large pterosaur tracks matched to its feet from Korea (CNUPH.p9. Haenamichnus. (Hwang et al. 2002.)

Figure 3. The large azhdarchid pterosaur, Zhejiangppterus. is shown walking over large pterosaur tracks matched to its feet from Korea (CNUPH.p9. Haenamichnus. (Hwang et al. 2002.)

6. Elongate femur (>1.6 humeral length). Increases stride efficiency; decreases attitude of axial column during feeding. In azhdarchids the femora is not relatively longer than in precursor taxa. The humerus is relatively shorter than in most pterosaurs and shorter than azhdarchid precursors like n42 in particular (Fig. 4). The torso is also relatively shorter, but this is also true of tiny precursor azhdarchids, like n42.  l7. Narrow-gauge trackways (Haenamichnus). Sub-vertical limbs providing efficient carriage when walking. – The Witton and Naish drawing overlooks the shallow angle of the femoral head relative to the shaft that would have produced a relatively sprawling, lizard-like femoral angle, as preserved in situ. Even so, the ankles would have remained below the body so long as the knees were below the acetabulum. It is also clear that pterosaur knees were bent during terrestrial locomotion, as in virtually all tetrapods.  8. Compact, padded pes and manus. Maximizes outleaver forces during step cycle; cushioning and increased traction on firm ground. – Witton and Naish based this claim on such loose and sloppy ichnites that individual toes were not distinct. Pads are also not distinct other than in the original drawing. When you look at the actual pes of Zhejiangopterus (Fig. 1) the metatarsus is indeed compact, narrower than in all other pterosaurs. 

Quetzalcoatlus scraping bottom while standing in shallow water.

Figure 4. Quetzalcoatlus scraping bottom while standing in shallow water. Note the attempt here to shift weight posteriorly while the neck is extended anteriorly. Keeping the wing finger close to the forelimb reduces the exposed wing area, important for underwater stability. The air-filled skull is weightless when in water. Not so when terrestrial stalking.

If, on the other hand, azhdarchids were waders, as were their tiny ancestors, like n42 (Fig. 5), then we can see not only their original tall, thin, morphology and their gradual evolution to great size while maintaining their wading niche (Fig. 5), but also a reason for getting bigger; gradually deeper water access. Unfortunately, Witton and Naish make no attempt to nest azhdarchids phylogenetically and certainly make no reference to their tiny ancestors.

Sisters to Microtuban

Figure 5. Sisters to Microtuban include No. 42 (more primitive) and Jidapterus (more derived).

The actual trackmaker of Haenamichnus had fingers (digits 1-3) as long as its foot. That is not found in Zhejiangopterus, but is found in Jidapterus (Fig. 5), a precursor azhdarchid.

Azhdarchids and Obama

Figure 6. Click to enlarge. Here’s the 6 foot 1 inch President of the USA alongside several azhdarchids and their predecessors. Most were knee high. The earliest examples were cuff high. The tallest was twice as tall as our President. This image replaces an earlier one in which a smaller specimen of Zhejiangopterus was used.

We already have pterosaurs that could have been terrestrial stalkers, like ground hornbills. We call them germanodactylids (Fig. 7). And THEY have horny/bony crests and a sharp, dangerous beak like a hornbill!

Germanodactylus and the Dsungaripteridae

Figure 7. Germanodactylus and the Dsungaripteridae. Click to enlarge. If any pterosaurs were like ground hornbills, these even had horn bills!

The beak tip of azhdarchids is a better pick-up tweezers than a stabbing knife. Better for picking up defenseless invertebrates than for stabbing terrestrial prey capable of fighting back or running away. Remember, when you go back further in azhdarchid phylogeny, you come to dorygnathids, a clade that also gave rise to wading ctenochasmatids. The devil is in the details Witton and Naish give us a pterosaur metacarpus with the false Bennett configuration (Fig. 8) in which metacarpals 1-3 are rotated as a set, like a closed draw bridge, against the anterior (formerly dorsal) surface of mc 4. That provides no space for all four extensor tendons. Now to get those fingers to hyper-extend laterally, Witton and Naish over rotate mc4 by another 90 degrees (Fig. 2). But now their wing opens laterally, no longer in the plane of the wing, as all fossils indicate.

Pterosaur finger orientation in lateral view

Figure 8. Pterosaur finger orientation in lateral view, the two hypotheses. On the left the Bennett hypothesis. On the right the Peters model that is supported by all fossil pterosaurs. These images graphically show how gracile metacarpals 1-3 were and why they could not support the weight of the pterosaur during terrestrial locomotion. The Bennett migration of the metacarpals is another problem. Witton and Naish take the Bennett mc4 one step further by rotating it another 90 degrees in order to produce lateral finger impressions. during hyperextension.

Witton and Naish give us a metacarpus and wing finger that should impress the substrate, but no pterosaur ichnite ever shows an impression of mc4 or the wing finger. So we know those two elements were held aloft during terrestrial locomotion, no matter how much Witton and Naish (and others see figure 9) wish otherwise. Witton and Naish give us a pteroid (Fig. 2) articulated to the preaxial carpal (another Bennett mistake) when the pteroid actually articulates with the radiale. Only soft tissue connects the pteroid and preaxial carpal. Witton and Naish give us pterosaur free fingers that don’t match tracks and don’t match bones. Witton and Naish illustrated from their imagination, both in shape and orientation. Witton and Naish currently hold court on pterosaur morphology, but I think you’ll agree they do so with false reconstructions. These two need to adopt strict and precise standards in which the bones agree with the ichnites and vice versa. Witton and Naish support the forelimb launch in all pterosaurs including giant Quetzalcoatlus. Considering the strain that would run through the three tiny fingers and three slender metacarpals, why do so many smart people take this idea seriously? Earlier we noted the morphological falsehoods artists added to the hand of an anhangueird pterosaur (Fig. 9) to make their forelimb launch hypothesis more logical and appealing by reducing the three free fingers and hoping the giant mc4 and wing finger made an impression in the substrate — but they don’t.

Errors in the Habib/Molnar reconstruction of the pterosaur manus

Figure 9. Errors in the Habib/Molnar reconstruction of the pterosaur manus. This manus uses the false Bennett reconstruction adopted by Witton and Naish and shortens the fingers. Corrections are provided in the lower images.

BTW I’m not blackwashing ALL of the output of Witton and Naish, just the above dozen or so problems. References Witton M and Naish D 2013. Azhdarchid pterosaurs: water-trawling pelican mimics or “terrestrial stalkers”? Acta Palaeontologica Polonica. available online 28 Oct 2013 doi:http://dx.doi.org/10.4202/app.00005.2013

When pterosaur workers dismiss

Earlier we looked at a new PeerJ paper by Mark Witton (2015) on the possibility of inept terrestrial pterosaurs:

Witton MP 2015.Were early pterosaurs inept terrestrial locomotors? PeerJ 3:e1018<doi: https://dx.doi.org/10.7717/peerj.1018

Witton chose (as you’ll see below by this own admission) to ignore any data on bipedal pterosaurs by Peters and others. The ignored data makes pterosaurs as agile as living birds on land. I pointed that out to him through the appropriate forum, which is the whole point of PeerJ feedback. Here’s how it went back and forth. Check out the blue links wherever possible. And don’t forget to read to the concluding paragraph after the last list of references this time.

This was my first list of suggestions, along with a required headline:

Why was published literature by Peters ignored when it addresses so many of the issues raised and dismissed by the Witton manuscript?

Several papers and a website by Peters (see below) address several problems ignored by this manuscript/paper including:

  1. Basal pterosaur ichnites (they are known, have been published and none are quadrupedal, some are digitigrade)
  2. The origin of pterosaurs (among bipedal fenestrasaurs each with uropatagia, trailing each hind limb). Objections to this scenario by Hone and Benton (2007, 2008) were due to typos in their dataset and deletion of two fenestrasaurs and 75% of the data from a third along with deletion of all data from Peters 2000, an original candidate facing the alternate scenario, among many other problems).
  3. The presence or absence of compressed metatarsals on pterosaurs, (typical keys to digitgrady and plantigrady).
  4. The uropatagium problem. (So far observed only in one specimen, Sordes, which was shown to be an illusion caused by bone and membrane dislocation during taphonomy. All other pterosaurs and their predecessors have twin uropatagia).

References
Peters, D. 1995. Wing shape in pterosaurs. Nature 374, 315-316.
Peters, D. 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods. Ichnos, 7: 11-41
Peters, D. 2000b. A redescription of four prolacertiform genera and implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106: 293-336.
Peters, D. 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. Historical Biology 15: 277-301.
Peters, D. 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27.
Peters, D. 2009. A Reinterpretation of Pteroid Articulation in Pterosaurs – Short Communication. Journal of Vertebrate Paleontology 29(4):1327–1330, December 2009
Peters, D. 2010. In defence of parallel interphalangeal lines. Historical Biology iFirst article, 2010, 1–6 DOI: 10.1080/08912961003663500
Peters, D. 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos 18(2):114-141.
Peters, D. 2010-2015. http://www.reptileevolution.com
https://pterosaurheresies.wordpress.com/2015/03/10/the-evolution-of-the-sordes-wing-and-uropatagia-1971-to-2011/
Hone DWE and Benton MJ 2007. An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles. Journal of Systematic Palaeontology 5:465–469.
Hone DWE and Benton MJ 2008. Contrasting supertree and total evidence methods: the origin of the pterosaurs. Zitteliana B28:35–60.

Response from the author (Mark P. Witton)
The assertion that the work of Peters has been ignored by this paper implies poor scholarship on my behalf, and that the works listed in Peters’ comment are as worthy of discussion as any other piece of pterosaur literature. It is true that Peters’ body of work did not inform my article, but my reasons for overlooking his papers will be familiar to those who follow pterosaur research.

My goal here is not to engage or argue with Peters. I – and my colleagues – have learned this is a largely futile exercise. Nor do I intend to write additional comments on this point or respond to his inevitable replies. However, for the benefit of naive parties reading these comments, some context may be useful. Because the substantial, fundamental problems with Peters’ research – the cause for myself and other workers ignoring his past contributions – are so well known to those studying fossil reptiles, I need only summarise them here. More detailed overviews of Peters’ work, the miseducation now synonymous with his name, and his attitude to other researchers, are provided by Bennett (2005) and Naish (2012) – links to these pieces are provided below.

The works of David Peters, including those related to subjects he mentions above (claims of non-pterodactyloid trackways, interpretation of pterosaur wing shapes, phylogenetic conclusions and limb function) are beyond controversial: they have been demonstrated as unreliable and untrustworthy by multiple authors (e.g. Unwin and Bakhurina 1995; Bennett 2005; Hone et al. 2009; Elgin et al. 2011). Infamously, at the core of all Peters’ work are tracings of photographs of fossil specimens, which he obtains using books, papers and online image searches. He claims to find specimen details in these photographs which no-one else has seen, including large portions of skeletons invisible to the naked eye; enormous, but invisible sheets of soft-tissue; and minute details – individual bones and fenestrae – in poorly-preserved, crushed regions of 2D fossils. These interpretations inform all his palaeobiological hypotheses, including his numerous alternative takes on extinct animal anatomy and functionality, as well as his entirely idiosyncratic concept of amniote phylogeny, which bears little resemblance to those based on standard molecular or morphological approaches.

Finding the structures Peters’ purports to uncover via his computer screen proves impossible when looking at actual specimens, even using detailed examination techniques such as CT scanning or microscopy (e.g. Unwin and Bakhurina 1995; Bennett 2005; Elgin et al. 2011). It is widely agreed by specialists that he is ascribing significance to artefacts of preservation and preparation, shadows in photographs, and other phenomena unrelated to actual specimen morphology (e.g. Unwin and Bakhurina 1995; Bennett 2005; Elgin et al. 2011; Naish 2012). Those workers who have conducted dedicated investigations of Peters’ methods provide wholly damning assessments of his ideas and techniques. On Peters’ ‘hinge-lines’ method of identifying track makers and foot function, Hone et al. (2009) “strongly advise against the use of hinge lines as a guide to functional analysis, a source of phylogenetic information, or a basis for identifying trackmakers in the ichnological record”. On digitally tracing photographs to find ‘missing’ fossil anatomies, Bennett (2005) has said “Peters’ method is flawed and his reconstructions are fantasy”. The same technique prompted Elgin et al. (2011) to describe his methods as “subjective and produc[ing] false and often fantastical images that have no value to science in general”. As early as 1995, Unwin and Bakhurina were calling his methods “unreliable”.

First-hand experience with many specimens Peters’ claims to have reinterpreted has led to my complete agreement with those denouncing his work in print: it is obvious that his papers and online articles are informed by pareidolia and personal opinion instead of an objective, scientific approach. I am aware of no practising researchers who argue differently.

Here and elsewhere, Peters argues his work is being ignored, and that workers like myself are taking ‘blinkered’ approaches to avoiding his controversial ideas. His persistent negative appraisals of virtually all findings in reptile palaeontology are now as well known as his tracing-based interpretations. Alas, one individual stating they are ‘right’ and that all other practising vertebrate palaeontologists are ‘wrong’ (as he regularly professes at his blog and website) does not make for controversy, nor does their insistence of scientific validity refute the considerable discussion showing their work as critically, fundamentally flawed (see Naish 2012 for the history, references and links surrounding Peters’ work). It seems the only individual bemoaning the lack of David Peters citations in contemporary pterosaur research is David Peters: others, including myself, see little to no benefit in the continued discussion of his unscientific, flawed approaches.

References
Bennett, S. C. 2005. Pterosaur science or pterosaur fantasy? Prehistoric Times, 70, 21-23. (direct link: http://bigcat.fhsu.edu/biology/cbennett/Bennett-PT-article.pdf)
Elgin, R. A., Hone, D. W., & Frey, E. (2011). The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica, 56, 99-111.
Hone, D. W., Sullivan, C., & Bennett, S. C. (2009). Interpreting the autopodia of tetrapods: interphalangeal lines hinge on too many assumptions. Historical Biology, 21, 67-77.
Naish, D. 2012. Why the world has to ignore ReptileEvolution.com. Tetrapod Zoology (direct link: http://blogs.scientificamerican.com/tetrapod-zoology/2012/07/03/world-must-ignore-reptileevolution-com/)
Unwin, D.M. and Bakhurina, N.N. 1995. Wing shape in pterosaurs. Nature 374, 316.

My response:
It is odd and unprofessional to attack the writer of a helpful comment (and his methods) while continuing to ignore the specimens of pes only tracks in the literature (see below).

With regard to Witton’s references, Bennett 2005 (writing in a fanzine) was correct in his assessment of earlier mistakes by Peters (also writing in a fanzine). None of this is in the academic literature.

On the same note, but elevated to the academic literature, Bennett (2007) made numerous observational errors (mistaking a maxilla for a sclerotic ring and ignoring the actual sclerotic rings, to name but a few). So mistakes happen. Corrections are made. This is the process of Science.

Evidently Witton does not forgive fanzine notions, but instead ascribes all future output as tainted. If so, then all of his example authors are likewise tainted:

Elgin, Hone and Frey (2011) made several mistakes in observations using crude cartoonish drawings to poorly trace subtle wing membranes, missing many details.

Hone, Sullivan and Bennett (2009) intended to disprove the universal hypothesis of parallel interphalangeal hinge lines, but avoided using all of the best examples (tetrapods with four and five digits). Even so they several times admitted to recovering hinge lines, even on three-toed taxa in which the digits were fully flexed and therefore not in their ‘useful’ positions.

In a blogpost Naish (2012) used artwork from paleoartists other than Peters to demean discarded hypotheses and observations, again (as above), not originating in the academic literature.

Unwin and Bakhurina (1995) failed to show the displacement of the left radius and ulna of their holotype Sordes specimen, which displaced the associated wing membrane and has since been misinterpreted as a leg-spanning uropatagium. No other pterosaur has documented a similar morphology. That is because this hypothesis is based on a misinterpretation/illusion.

Witton himself has employed imagination in his reproductions of an embryo pterosaur (Pterodaustro) with a large orbit and small rostrum when the data shows that all pterosaur embryos, juveniles and subadults had adult proportions, and in this regard are different than many other tetrapods. I could list many other observational errors.

It is important to show mistakes without rancor. It is also important not to dismiss all future output of a worker based on a few misinterpretations early in a career published in a fanzine. I certainly do not intend to brand any of the above workers the way Witton has branded Peters, but reserve the right to be critical, only if necessary, of any future output.

Bottom line, because there are several examples of bipedal pterosaur ichnites in the academic literature it is incumbent upon the author to address these examples and not ignore them. This is the academic forum for Witton to address his issues with all bipedal pterosaur tracks in the literature. It is also incumbent upon the author to treat peer-reviewed literature with more attention than he treats fanzines or blogposts that were not peer-reviewed.

References
Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.
Conrad K, Lockley MG and Prince NK 1987. Triassic and Jurassic vertebrate-dominated trace fossil assemblages of the Cimarron Valley Region: Implications for paleoecology and biostratigraphy. New Mexico Geological Society Guidebook. 38th Field Conference, Northeastern New Mexico 1987. 127-138.
Lee YN, Azuma Y, Lee H-J, Shibata M, Lu J 2009. The first pterosaur trackways from Japan. Cretaceous Research 31, 263–267.
Kim JY, Lockley MG, Kim KS, Seo SJ and Lim JD 2012. Enigmatic Giant Pterosaur Tracks and Associated Ichnofauna from the Cretaceous of Korea: Implication for the Bipedal Locomotion of Pterosaurs. Ichnos 19 (1-2): 50-65.DOI:10.1080/10420940.2011.625779

I’ll add here in conclusion
the current crop of pterosaur workers continues to wonder where pterosaurs originated, even though that was established 15 years ago. They continue to hold the purported uropatagium of Sordes as their paradigm, rather than recognize it for what it is, a taphonomic shift of wing elements. They do not recognize the digitigrade nature of basal pterosaur pedes despite the great match they make with Rotodactylus tracks, the only ichnites with digit 5 impressing far behind the other digits. And the list goes on. As Witton notes above, many current pterosaur workers consider my list of peer-reviewed academic literature unworthy of even considering. If it’s so wrong, it should be easy to dismantle. But to ignore this literature is to keep the blinders on.

And that’s why this blogpost continues…

And Mark Witton, if you’re reading this:
don’t believe anything I write, but please do check out for yourself the Triassic and Jurassic pterosaur specimens and gauge them against the tracks I suggest were made by them.

Walking azhdarchid movie matched to pterosaur tracks

Earlier Pterodactylus, a small pterodactylid pterosaur, was animated to match Craysaac tracks (Fig. 1). In this model the backbone is elevated higher here than in some of the wireframe pterosaurs you may have seen (Fig. 3) and the forelimbs carry little if any of the weight. Nevertheless, in this species they work like and impress like ski poles — doing the pterosaur walk.

Pterodactylus walk matched to tracks according to Peters

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

Today, Zhejiangopterus (Cai and Wei 1994), a large azhdarchid pterosaurs, is similarly animated to match large Korean pterosaur tracks (Hwang et al. 2002; Fig. 2).

Note how Zhejiangopterus carries its head, with the middle ear region above the center of gravity, like a human. At any point Zhejiangopterus could lower its skull for a meal or a drink. It could also raise its wings without shifting its balance to initiate a bipedal takeoff. Note how little the forelimbs actually touch the substrate. Again, this is the ski-pole hypothesis in which the forelimbs are used mainly to steady the pterosaur, not to generate thrust or support the weight (exception noted below).

Figure 2. The large azhdarchid pterosaur, Zhejiangppterus. is shown walking over large pterosaur tracks matched to its feet from Korea (CNUPH.p9. Haenamichnus. (Hwang et al. 2002.)

Figure 2. The large azhdarchid pterosaur, Zhejiangppterus. is shown walking over large pterosaur tracks matched to its feet from Korea (CNUPH.p9. Haenamichnus. (Hwang et al. 2002.) The feet are planted just as the hands are lifted. Click to enlarge and animate if not moving.

The troubles with the horizontal backbone model are at least threefold

  1. The skull would be far from the center of gravity at the end of a long neck. Bearable, perhaps, in tiny Pterodactylus. unwieldy on giant Zhejiangopterus with its oversized skull.
  2. The forelimbs would bear most of the weight with the skull far beyond them. This is fine when floating and poling.
  3. Standing up to open the wings for display or flight would involve throwing the skull backward to end up standing bipedally. Awkward. Time consuming. The competing quad launch hypothesis is out of the question as reported earlier here and elsewhere for the reasons listed therein.
Figure 3. The horizontal backbone hypothesis for quadrupdal pterosaurs. This hypothetical model is supposed to match tracks, but the tracks can be matched to a genus and species, so why not use it?

Figure 3. The horizontal backbone hypothesis for quadrupdal pterosaurs (Mazin et al. 2009). This hypothetical model is supposed to match tracks, but the tracks can be matched to a genus and species, so why not use it? Click to enlarge. Note the massive bending of the wrist here. Completely unnecessary. 

Mazin et al. (2009) published a series of imagined wireframe pterosaurs matched to the tracks (Fig 3). This is odd because a former champion of bipedal pterosaurs was co-author Kevin Padian, who was a quad ptero-track denier for many years until the Craysaac tracks won him over (while continuing to deny the pterosaur nature of other tracks. Odder still because the animation that was used for the public (which I saw year ago and not sure if it is still in use, but is not used here) showed a more upright Pterodactylus.

Note: The published wire frame model might match the gait and placement of the ptero tracks, but the manus and pes of the wireframe model are but a small fraction of the size of the tracks. This is something the authors and their referees missed, or overlooked. But we all know, the devil is in the details.

“If the glove doesn’t fit, you must acquit.” — Johnny Cochran at the OJ Simpson murder trial.

And if the feet and hands don’t match,
you’ve got the wrong wire frame pterosaur model. Contra Mazin et al., I took the effort to match the manus and pes track to an extinct taxon. In Science, you must use the data as precisely as you can, and let those data tell you, as closely as possible, how to build your model. Don’t walk in with your pet hypothesis and try to shoehorn or BS your way through it, unless you can get away with it, as Mazin et al. did until now.

Figure 4. Zhejiangopterus at a stage in its walking cycle in which the right manus bears nearly all the weight.

Figure 4. Zhejiangopterus at a stage in its walking cycle in which the right manus bears nearly all the weight. M. Habib noted the arm bones were much stronger than they needed to be for flight. Well, maybe that’s because Zhejiangopterus was walking on its forelimbs. Birds don’t do that. BTW that’s the same force vector Habib imagined for his ill-fated quad takeoff. I hate to say it, but this pose makes more sense in every way.

If my model of pterosaur walking is correct,
and I’m sure it has minor flaws that may never be known, then the tiny manus bears nearly the entire weight of the pterosaur at one and only one brief point in the step cycle (Fig. 4) that does not need support in normal bipedal walking. The tiny area of the tiny fingers is likely to impress deeper because the weight of the pterosaur is concentrated on a smaller area (compared to the long foot) in contact with the substrate. This pose also might answer Mike Habib’s original mystery as to why the pterosaur humerus was built stronger than it needed to be for flight. Birds don’t put their weight on the forelimbs. And few bats do (the tiny vampire is the exception).

Here are the alternative models 
for pterosaur quadrupedal standing (Fig. 5) for ready comparison. Which of these provides a bended knee with the proper vectors for thrust? The manus doesn’t have to and didn’t provide thrust, but it should not have been placed so far forward that it could only provide a braking vector to the shoulder.

Click to enlarge. Averinov re-published images of Zhejiangopterus and Quetzalcoatlus from Witton 2007 and Wittion & Naish 2008 that demonstrate a certain devil-may-care attitude toward the anatomy, especially in Quetzalcoatlus. There was little regard for the the shape of the pelvis in both images and little regard for the lengths of the cervical elements and robust pectoral girdle in Q. My images, on the other hand, were traced from photos taken during a visit to Texas several years ago.

Figure 5. Click to enlarge. Averinov re-published images of Zhejiangopterus and Quetzalcoatlus from Witton 2007 and Wittion and Naish 2008 that demonstrate a certain devil-may-care attitude toward the anatomy, especially in Quetzalcoatlus. Moreover, just imagine the long lever problems these two have with that long extended neck while walking and the tremendous strain put on that forelimb, which is not angled correctly to provide thrust. It don’t provide thrust in the more upright pose either, but it doesn’t need to. In that case it merely provides some stability.

On the other hand, a feeding pterosaur in water might have looked something like this (Fig. 6).

Quetzalcoatlus scraping bottom while standing in shallow water.

Figure 6. Quetzalcoatlus scraping bottom while standing in shallow water. Here the hollow and airy skull is nearly weightless or even buoyant in water. 

 

References
Cai Z and Wei F 1994. On a new pterosaur (Zhejiangopterus linhaiensis gen. et sp. nov.) from Upper Cretaceous in Linhai, Zhejiang, China.” Vertebrata Palasiatica, 32: 181-194.
Hwang K-G, Huh M, Lockley MG, Unwin DM and Wright JL 2002. New pterosaur tracks (Pteraichnidae) from the Late Cretaceous Uhangri Formation, southwestern Korea. Geology Magazine 139(4): 421-435.
Mazin J-M, Jean-Paul Billon-Bruyat J-P and Padian K 2009. First record of a pterosaur landing trackway. Proceedings of The Royal Society 276:3881–3886.
online pdf 
Unwin D and Lü J. 1997. 
On Zhejiangopterus and the relationships of Pterodactyloid Pterosaurs, Historical Biology, 12: 200.

wiki/Zhejiangopterus