SVP abstracts 9: Pushing a tiny wading pterosaur into the deep end

Habib, Pittman and Kaye 2020
add laser fluorescence to a tiny pterosaur, the still unnamed Berlin specimen, MB.R.3531 (Figs. 1a, b) we first looked at following Flugsaurier 2018.

From the Habib et al. abstract:
“Water launch capacity has been previously suggested for some marine pterosaurs based on osteological grounds, but robust estimates of specimen-specific performance are difficult without robust estimates of wing area and potential hindfoot webbing. Here, we provide the first estimates of pterosaur water launch performance that take into account preserved soft tissue anatomy.”

FIgure 1. Reconstruction of MB.R.3531, nesting with Eoazhdarcho, Eopteranodon and Aurorazhdarcho.

FIgure 1a. Reconstruction of MB.R.3531, nesting with Eoazhdarcho, Eopteranodon and Aurorazhdarcho. Shown about actual size, so this pterosaur could have stood upright like this in a 10cm per side box. See figure 1b.

Figure 1. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx to scale.

Figure 1b. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx (not a juvenile) to scale. The smaller one had better stay out of deeper waters.

Continuing from the Habib et al. abstract:
“The aurorazhdarchid pterosaur specimen MB.R.3531 from the Upper Jurassic Solnhofen Limestone was imaged using Laser-Stimulated Fluorescence, revealing significant soft tissue preservation. These soft tissues are among the best-preserved of any known Jurassic pterosaur, including for the first time, a complete actinofibrillar complex, an undistorted actinopatagium with the retrophalangeal connective tissue wedge and entire trailing edge, and webbed feet.”

Why the showmanship (= hyperbole, = falsehood)? Most of these traits have been known for several pterosaurs and from less jumbled specimens, including the  Zittel wing specimen of Rhamphorhynchus (Fig. 2), the dark-wing specimen of Rhamphorhynchus and the Vienna specimen of Pterodactylus (Fig. 3).

The Zittel wing

Figure 2. The Zittel wing from a species of Rhamphorhynchus. This is real. There is no way this wing membrane is going to stretch to the ankles. See figure 3 for comparison and phylogenetic bracketing. This is how pterosaur wings were able to be folded away when not in use. 

Figure 2. Here is the Vienna specimen of Pterodactylus in situ and with matrix removed. Now compare this figure with figure 3, which shows the wings and uropatagia unfolding. There is no way to turn this into a deep chord wing membrane. And it decouples the forelimbs from the hind limbs.

Figure 3. Here is the Vienna specimen of Pterodactylus in situ and with matrix removed. Now compare this figure with figure 3, which shows the wings and uropatagia unfolding. There is no way to turn this into a deep chord wing membrane. And it decouples the forelimbs from the hind limbs. This is how pterosaur wings were able to be folded away when not in use. 

Continuing from the Habib et al. abstract:
“These physically validated soft tissues formed the basis for analyzing water launch capability in MB.R.3531. We modeled the water launch as quadrupedal and broadly similar to modern “puddle jumping” anseriform birds that use a combination of their webbed feet and partially folded wings to push against the water surface during takeoff.”

More myth-making. Like the morphologically similar by convergence, Pterodactylus (based on the Vienna specimen; Figs. 3, 4), MB.R.3531 was a quadrupedal wader (note the tiny fore claws), but able to stand bipedally prior to take-off. Waders don’t get themselves into water too deep to touch the substrate. Ask any sandpiper, plover or stilt.

So this is much ado about nothing, based on putting the discredited Habib method of pushup take-off back on the table.

FIgure 6. Pterodactylus scolopaciceps (n21) model. Full scale.

Figure 4. Pterodactylus scolopaciceps (n21) model. Full scale. This is how pterosaur wings were able to be folded away when not in use. 

More from the Habib et al. abstract:
“Under this model, both hind limb and forelimb contact areas are critical. Under conservative assumptions regarding power and range of motion, we predict that MB.R.3531 was capable of rapid takeoff from the water surface.

Yes, of course, but from a bipedal start (Fig. 5). And from shallow ponds, no deeper than knee deep.

FIgure 8. Dimorphodon take off (with the new small tail).

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

From the Habib et al. abstract:
“Our model predicts that water launch performance in pterosaurs was particularly sensitive to three factors: available propulsive contact area, forelimb extension range, and extension power about the shoulder. MB.R.3531 possessed both osteological and soft tissue features that significantly enhanced these performance characteristics (including, but not limited to, expanded internal rotator/extensor attachments on the proximal humerus, extended humeral length, chordwise distal actinofibril orientation, and webbed pes).”

If you’ll compare one with another, MB.R.3531 (Fig. 1) is convergent in most respects to a typical Solnhofen Pterodactylus (Fig. 4), down to the webbed feet. There was nothing out of the ordinary about MB.R.3531.

“These features would have limited impact on flight performance. We therefore interpret them as likely water takeoff specializations.

Whoa, partner! These traits are typical of most beach combing pterosaurs, so far as they can be determined in fossils and phylogenetic bracketing, even with unrelated clade convergence.

“The osteological specializations in MB.R.3531 are subtle, which may be related to its small size.”

I would agree that the osteological specializations are so subtle they do not exist.

“Larger marine pterosaurs appear to exaggerate these characteristics, which matches expectations from scaling.

This is false. Ornithocheirids have notoriously tiny feet, unsuitable for anything more than standing still and walking slowly. More to come.

“We show that soft tissue data can be used to help validate the dynamic feasibility of water launch in pterosaurs, suggesting it was a regular part of foraging behavior in some taxa.”

This is false. Dr. Habib, just let the pterosaur stand upright, as its ancestors did and as it was designed to do (fused sacrals and fused dorsal vertebrae dorsally, sternum + gastralia + prepubes support ventrally). Quadrupedal pterosaur tracks are more prevalent because they were made by a few clades of small-fingered beach combing pterosaurs, principally pterodactylids, ctenochasmatids and azhdarchids (Peters 2011).

Pelican take-off sequence from water.

Figure 6. Pelican take-off sequence from water using kicking webbed feet and elevated, then flapping wings simultaneously. Click to enlarge.

From an earlier 2018 assessment of MB.R.3531:
Habib and Pittman 2018 bring us a rarely studied Berlin pterosaur, MB.R.3531 (Fig. 1) originally named Pterodactylus micronyx, then Aurorazhdarcho micronyx. This specimen nests with other wading pterosaurs, AurorazhdarchoEopteranodon and Eoazhdarcho forming  a clade overlooked by other workers, at the transition between germanodactylids and pteranodontids, not related to azhdarchids (Peters 2007).

For those wondering why I don’t publish more.
Why put in the effort if competing studies are ignored? The online way is faster, briefer and can be animated with no color charges. Furthermore, the vetting process prior to publication of hypotheses like the dangerous pushup launch and the bat-wing pterosaur membrane myth, is failing time and again. Editors, professors and researchers who should be earning their paycheck from rigorously testing new hypotheses are instead granting their friends free passes in an effort to keep the status quo in lectures and textbooks.


References
Habib M and Pittman M 2018. An “old” specimen of Aurorazhdarcho micronyx with exceptional preservation and implications for the mechanical function of webbed
feet in pterosaurs. Flugsaurier 2018: The 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 41–43.
Habib MB, Pittman M and Kaye T 2020. Pterosaur soft tissues revealed by laser-stimulated fluorescence enable in-depth analysis of water launch performance. SVP abstracts 2020.
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
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. http://dx.doi.org/10.1080/10420940.2011.573605

https://pterosaurheresies.wordpress.com/2018/03/23/pteranodon-quad-hopping-water-takeoff-according-to-the-amnh/

https://pterosaurheresies.wordpress.com/2018/08/12/flugsaurier-2018-web-footed-little-pterosaur-mb-r-3531/

https://pterosaurheresies.wordpress.com/2012/12/16/water-takeoff-in-a-pelican-part-2-with-reference-to-pterosaur-water-takeoffs/

https://pterosaurheresies.wordpress.com/2015/03/23/amnh-animated-pterosaur-takeoffs/

https://pterosaurheresies.wordpress.com/2012/04/07/pterosaur-take-off-from-water/

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

https://pterosaurheresies.wordpress.com/2015/05/23/pterosaur-launch-talk-from-2012-on-youtube/

First non-pterodactyloid pterosaurian trackways ever described? …No

Updated April 18. 2020
The four-fingered manus tracks (identified below out of context as a rhamphorhynchid pes track) belong to a tenrec, not a pterosaur. Details here. 

Mazin and Pouech 2020
report on basal pterosaur tracks from the “Pterosaur Beach of Crayssac” (Upper Jurassic), which they consider novel.

From the abstract:
“New discoveries on the ichnological site known as “the Pterosaur Beach of Crayssac” (lower Tithonian, Upper Jurassic; south-western France) answer the question of terrestrial capabilities of non-pterodactyloid pterosaurs. If the terrestrial type of locomotion of pterodactyloid pterosaurs has been solved from ichnological evidence for more than twenty years, no tracks and trackways referable to non-pterodactyloid pterosaurs have ever been described.”

Not true. Peters 2011 included several anurognathid tracks and matched them to trackmakers (Fig. 1). We looked at the so-called ‘Sauria aberrante‘ from Patagonia earlier here in 2011.

Digitigrade pterosaur tracks

Figure 1. A pterosaur pes belonging to a large anurognathid, “Dimorphodon weintraubi,” alongside three digitigrade anurognathid tracks and a graphic representation of the phalanges within the Sauria aberrante track.in

Continuing from the abstract:
“Thus, the debate on terrestrial capabilities of these non-pterodactyloids was based on morpho-functional studies, with the main conclusion that those pterosaurs were arboreal dwellers and bad walkers.”

Not true. Peters 2000a, b, 2011, demonstrated a bipedal ability in pterosaurs superior to that of extant bipedal lizards, (e.g. Chlamydosaurus).

The ‘bad-walker myth’ results from mythology promoted by Unwin and Bakhurina1994 with regard to several misinterpretations of Sordes pilosus. including the invalid binding of the hind limbs with a uropatagium along with the invalid continuation of the brachiopatagium trailing edge to the ankle.

Dimorphodon pes with shadows.

Figure 2. Dimorphodon pes with shadows. Pedal digit 5 can swing beneath the metatarsus. Note elevated proximal phalanges.

“Six trackways referable to three non-pterodactyloid new ichnotaxa, maybe closely related to Rhamphorhynchidae, are described in this work. Their study leads to the conclusion that grounded non-pterodatyloids, at least during the Late Jurassic, were quadrupedal with digitigrade manus and plantigrade to digitigrade pes.”

This confirms work by Peters 2000a, b, 2011.

“They were clearly good walkers, even if hindlimbs are supposed to be hampered by the uropatagium, what could have constrained the terrestrial agility of these animals.”

A single binding uropatagium is a myth invalidated several years ago. See above.

“Thus, from ichnological evidence and contrary to the current hypotheses, non-pterodactyloid pterosaurs seem to have been good walkers even though their trackways are very rare or unidentified to date.”

This also confirms work by Peters 2000a, b, 2011.

Cosesaurus matched to Rotodactylus from Peters 2000.

Figuue 3.  Cosesaurus matched to Rotodactylus from Peters 2000.

Continuing from the abstract:
“This rarity could be due to behaviour rather than to functional capacities, many non-pterodactyloids being considered both littoral fishers and arboreal or cliff dwellers. However, the concept of non-pterodactyloid “good climbers and bad walkers” has to be modified to “good climbers and rare walkers”, unless many non-pterodactyloid ichnites have yet to be discovered.”

Many non-pterodactyloid ichnites have been discovered (Fig. 1). Unfortunately, they have been ignored and omitted by authors, including Mazin and Pouech. It’s never a good time to remember Dr. S. Christopher Bennett’s infamous threat, “You will not be published. And if you are published, you will not be cited.”

Pes of Rhamphorhynchus and matching track

Figure 4. Crayssac track different from all others. Inset: Pes of Rhamphorhynchus muensteri JME-SOS 4009, no. 62 in the Wellnhofer catalog. NOTE ADDED APRIL 18, 2020. The Martin-Silverstone paper (link above) identifies this as a manus track. It belongs to a tenrec, not a pterosaur. 

This used to be considered
crankery. Now they confirm the heretical hypotheses, but claim them as their own.

Unique among Rhamphorhynchus specimens, Rhamphorhynchus muensteri (Wellnhofer 1975) JME-SOS 4009, no. 62 in the Wellnhofer catalog has a long digit 4.

Figur 5. Unique among Rhamphorhynchus specimens, Rhamphorhynchus muensteri (Wellnhofer 1975) JME-SOS 4009, no. 62 in the Wellnhofer catalog has a long digit 4.

BTW
Earlier a published Craysaac a basal pterosaur track was matched to the pes of a particular Rhamphorhynchus (no. 62, JME-SOS-4009; Figs. 4, 5) in a 2011 blogpost on digitigrade pterosaur footprints. I heard of the Crayssac rhamph-tracks years ago and am glad to see their present publication. Still awaiting the paper. When it comes: more details.

NOTE ADDED APRIL 18, 2020. The Martin-Silverstone paper (link above) identifies this as a manus track. It belongs to a tenrec, not a pterosaur.

Cosesaurus and Rotodactylus, a perfect match.

Figure 6. Cosesaurus and Rotodactylus, a perfect match. Elevate the proximal phalanges along with the metatarsus, bend back digit 5 and Cosesaurus (left) fits perfectly into Rotodactylus (right).

We also have tracks made by pre-pterosaur fenestrasaurs.
Rotodactylus, UCB 38023, Moenkopi Formation (Peabody,1948; Peters, 2000a; Figs. 3, 6)


References
Casamiquela RM 1962. Sobre la pisada de un presunto sauria aberrante en el Liassico del Neuquen (Patagonia). Ameghiniana, 2(10): 183–186.
Mazin J-M and Pouech J 2020. The first non-pterodactyloid pterosaurian trackways and the terrestrial ability of non-pterodactyloid pterosaurs. Geobios 16 January 2020. PDF
Peabody FE 1948.Reptile and amphibian trackways from the Lower Triassic Moenkopi formation of Arizona and Utah.  University of California Publications, Bulletin of the  Department of Geological Sciences 27: 295-468.
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 (3): 293–336.
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
Unwin DM and Bakhurina NN 1994. Sordes pilosus and the nature of the pterosaur flight apparatus. Nature 371: 62-64.

Sauria aberrante MLP 61-IX-4-1 (Casamiquela, 1962)
Track D, Sundance Formation (Harris and Lacovara, 2004)
Track C, Sundance Formation (Harris and Lacovara, 2004)

https://pterosaurheresies.wordpress.com/2012/03/02/the-case-against-bipedal-pterosaurs

https://pterosaurheresies.wordpress.com/2011/08/09/pterosaurs-bipedal-quadrupedal-or-both/

SVP 2018: Large bipedal pterosaur tracks in South Korea

Kim, Park and Paik 2018
remind us that large bipedal pterosaur tracks can be found in South Korea, something we looked at earlier here (Fig. 1). Remember, pterosaur experts ignored these in 2012 and every year since.

The pterosaur tracks (in black) crossing sauropod dinosaur tracks (in gray).

Figure 1. The pterosaur tracks (in black) crossing sauropod dinosaur tracks (in gray).

Kim et al. report: “The large and tetradactyl pes only tracks in these trackways indicate that track makers were erect, bipedal and large pterosaurs.The footprint fossils described here are classified as Haenamichnus gainensis, previously documented from the Lower Cretaceous Haman Formation underlain by the Jindong Formation.”

References
Kim HJ, Park JG and Paik IS 2018. Large pterosaur footprints from the Upper Cretaceous Jindong Formation of South Korea: Occurrence and paleoecological implications. SVP abstracts.

 

Flugsaurier 2018: Los Angeles County Museum

Flugsaurier
is a meeting of those interested in pterosaurs that happens in another part of the world every few years. I went to the first few. Saw a lot of specimens. Met a lot of colleagues. Produced a few abstracts and gave some presentations.

Over the next few days
there’s a Flugsaurier meeting taking place in Los Angeles. Many well-known and not-so-well known speakers are giving presentations this year. I will not be among them. Why?

So far as I know,
all of the conveners and many of the presenters continue to ignore a paper I wrote 18 years ago on the origin of pterosaurs from fenestrasaurs, not archosaurs. Other papers followed on wing shape, trackmaker identification and other topics, all supporting that phylogenetic hypothesis of relationships. Evidently workers would prefer to hope that pterosaurs arose from archosaurs close to dinosaurs. This is not where the data takes anyone interested in the topic who is not a party to taxon exclusion.

In addition, several of the conveners

  1. subscribe to the invalid quad-launch hypothesis
  2. the bat-wing reconstruction of the brachiopatagium.
  3. they believe that pedal digit 5 framed a uropatagium.
  4. They refuse to add tiny Solnhofen pterosaurs to their cladograms.
  5. They refuse to add several specimens of each purported genus to cladograms—and because of this they don’t recognize the four origins of the pterodactyloid-grade (not clade).
  6. They still don’t recognize that pterosaurs grew isometrically.
  7. They still don’t accept that pterosaur mothers retained their egg/embryo within the body until just before hatching (a lepidosaur trait).
  8. They still don’t accept that pterosaur bone fusion patterns follow lepidosaur, rather than archosaur patterns.
  9. They accept the idea that giant eyeballs filled the anterior skulls of anurognathids, not realizing that the supposed ‘scleral ring’ on edge of the flathead anurognathid is actually the mandible and tiny teeth.
  10. They reject any notion that all basal and some derived pterosaurs were bipedal, despite the footprint and morphological evidence proving bipedal locomotion.
  11. They all hold out hope that the largest azhdarchids could fly.
  12. I was going to say that all workers believe that crest size and hip shape identify gender, when the evidence indicates these are both phylogenetic markers, but then I found an abstract in 2018 that casts doubt on the gender/crest/pelvis hypothesis. So there’s hope.

That’s a fairly long list of ‘basics’
that most pterosaur workers ‘believe in’ despite the fact that there is no evidence for these false paradigms — but plenty of evidence for the lepidosaur origin of pterosaurs, from which most of the above hypotheses follow.

I am not attending Flugsaurier 2018
because the convening pterosaur workers deny and suppress the data listed above. Plus, I can more actively and thoroughly test assertions made during the conference from ‘my perch’ here in mid-America.

Good luck to those attending. 
Test all assertions and hypotheses, no matter their source.

Agadirichnus elegans pterosaur tracks rediscovered

Yesterday we looked at a recent online paper that expanded the list of pterosaur taxa present at the last days of pterosaurs and dinosaurs in the latest Cretaceous. Absent from that highly publicized work were the Maastrichtian pterosaur tracks made by ctenochasmatids (some quite large) listed below and the tupuxuarid skull described earlier.

Masrour et al. 2018
rediscover Maastrichtian (Late Cretaceous) dinosaurs, birds and enigmatic 8-9 cm pes tracks and 6cm manus tracks tentatively attributed to some sort of ‘Lacertilia’ under the name Agadirichnus elegans, first documented in Ambroggi and Lapparent 1954. The originals are now considered lost. The site in Morrocco was rediscovered. The enigma tracks were retrospectively identified as two pterosaur morphotypes.

Unknowingly,
these were the first pterosaur tracks ever named, preceding Pteraichnus by three years.

Etymology:
named after Agadir, the Moroccan city near the site.

Biggest takeaway:
There was a variety of pterosaurs in the Maastrichtian (Latest Cretaceous) that is presently underrepresented by skeletons (currently just giant azhdarchids and pteranodontids in rare fossiliferous strata worldwide).

Figure 1. A variety of tracks inappropriately labeled Agadirichnus. Here one pedal track is matched to Middle Jurassic Darwinopterus, perhaps by convergence. But maybe not.

Figure 1. A variety of tracks inappropriately labeled Agadirichnus. Here only one pedal track (B) is matched to Middle Jurassic Darwinopterus, perhaps by convergence. Note what appears to be pedal digit 5 beneath the heel.

The catalog of pterosaur pedes
(Peters 2011) was not cited, but I’ll use it to attempt a trackmaker identification.

A Pteranodon pes, UNSM 2062

Figure 1. A Pteranodon pes, UNSM 2062 as reconstructed plantigrade by Bennett (1991, 2001) and as reconstructed digitigrade. PILs added. Black elements are foreshortened during elevation into the digitigrade configuration. Some Pteranodon pedes were indeed plantigrade, depending on the species, but not this one based on PILs analysis. Note the distal and proximal tarsals are fused to each other.

Taxon B with pedal digit 3 the longest matches:

  1. Dimorphodon
  2. Darwinopterus (certain specimens only)
  3. Wukongopterus
  4. Ctenochasma elegans
  5. Pterodaustro
  6. Shenzhoupterus
  7. Pteranodon UNSM 2062 specimen only

Taxon B with digit 1 no longer than p2.2 matches

  1. Darwinopterus
  2. Wukongopterus
  3. Ctenochasma elegans
  4. Pterodaustro 
  5. Pteranodon UNSM 2062 specimen only

Taxon B with p4 subequal to mt 4 matches

  1. Pteranodon UNSM 2062 specimen only. Other tested Pteranodon specimens do not extend digit 3 beyond the others, as shown here. The only problem is: the fingers of Pteranodon cannot touch the substrate due to the long metacarpus relative to the short hind limbs. My guess: there was a large, as yet unknown, ctenochasmatid trackmaker in the Late Cretaceous. Ctenochasmatids had a short manual digit 1 and small dull claws on all digits matching the manus impression of Taxon A. Perhaps this was one of the giant ctenochasmatids, like Gegepterus, at present lacking data for both feet and fingers.

Taxon C with pedal digit 2 the longest, toes shorter than metatarsals and a narrow pes matches:

  1. Zhejiangopterus (probaby juvenile based on 6cm size)

Taxon D with pedal digit 2=3, toes shorter than metatarsals and metatarsal 4 much shorter than 1-3 matches:

  1. Ctenochasma

References
Ambroggi R and de Lapparent  AF 1954. Les empreintes de pas fossiles du Maestrichtien d’Agadir. Notes du Service Geologique du Maroc, 10:43–6.
Longrich NR, Martill DM, Andres B 2018. Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. https://doi.org/10.1371/journal. pbio.2001663
Masrour M, Ducla M d, Billon-Bruyat J-P and Mazin J-M 2018. Rediscovery of the Tagragra Tracksite (Maastrichtian, Agadir, Morocco): Agadirichnus elegans Ambroggi and Lapparent 1954 is Pterosaurian Ichnotaxon, Ichnos.  https://doi.org/10.1080/10420940.2017.1386661

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/

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