Flugsaurier 2018: Pteraichnus holotype color coded

Flugsaurier 2018 part 5
Since the purpose of the symposium is increase understanding of pterosaurs, I hope this small contribution helps.

The first pterosaur tracks
to be published (Stokes 1957. FIg. 1) were the subject of an abstract by Breithaupt and Matthews (2018). They created a color-coded digital elevation model (DEM) to which I added a slightly enlarged Pterodactylus longicullum as a trackmaker.

FIgure 1. Pteraichnus tracks scanned by Breithaupt and Matthews 2018 with Pterodactylus longicullum, slightly enlarged, to fit.

FIgure 1. Pteraichnus tracks scanned by Breithaupt and Matthews 2018 with Pterodactylus longicullum, slightly enlarged, to fit in a feeding posture.

The only problem is…
this virtually complete specimen of P. longicollum lacks fingers 1–3 and feet. So why did I do this?

Phylogenetic bracketing.
The pedal and manual impressions of the Pteraichnus track most closely match those of the much smaller, but related P. antiquus. So it’s a combination of phylogeny and size. No other taxa in the trackmaker guide to pterosaur feet (Peters 2011) are more similar to the hypothetical trackmaker than P. antiquus.

The feeding posture
Beachcombing pterosaurs like P. longicollum had long limbs to raise their bodies out of the surf that their feet and hands walked through. In this way they converged with larger and much larger azhdarchids. They were looking down for beach fauna and underwater fish and invertebrates. Although many clades of pterosaurs adopted beach combing for prey, many others did not and they did not have this same sort of quadrupedal posture.

References
Breithaupt BH and Matthews NA 2018. New visualizations of the three-dimensional, terrestrial world of the “dragon reptiles”: Pterosaur tracks and photogrammetric ichnology. Flugsaurier 2018: the 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 19–22.
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
Stokes WL 1957. Pterodactyl tracks from the Morrison Formation. Journal of Paleontology, 31, 952–954.

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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.

Anhanguera animation at the NHM (London)

This one started off with so much promise
as the animators at the National History Museum (NHM) in London assembled their version of the ornithocheirid pterosaur, Anhanguera, bipedally (Fig. 1), as you’ll see when you click on the video under ‘References’.

Figure 1. Animated by the NHM, Anhanguera is bipedal and flapping its literally oversize wings.

Figure 1. Animated by the NHM, Anhanguera is bipedal and flapping its literally oversize wings standing on oversize feet with an undersized skull and hyperextended elbows and unbalanced stance.

Unfortunately there were some morphology issues (compared in Fig. 2):

  1. wings too long
  2. sternal complex missing
  3. gastralia missing (but rarely preserved in ornithocheirids)
  4. feet way too big
  5. skull too small
  6. tail too short
  7. not sprawling
  8. free fingers too big
  9. wing fingers should tucked tight against elbows (in the same plane)
  10. one extra cervical
  11. anterbrachia too short and gracile
  12. elbows overextended (in Fig. 1)
  13. too much weight put on forelimbs, center of balance (wing root) should be over the toes
  14. Prepubes are extremely rare in ornithocheirds, but when present they are tiny, putter-shaped and oriented ventrally in line with the bent femora, not anteriorly
Figure 2. NHM Anhanguera compared to skeletal image from ReptileEvolution.com.

Figure 2. NHM Anhanguera compared to skeletal image from ReptileEvolution.com. There are at least 10 inaccuracies here. See text for list.

Also unfortunately, the video quickly devolved
to the invalid and dangerous quad launch, when (doggone it!) it was all set up to do a more correct and  much safer bird-like launch. The laws of physics and biomechanics are ignored here, but at least David Attenborough narrates.

Figure 3. NHM Anhanguera quad launch select frames.

Figure 3. NHM Anhanguera quad launch select frames. The laws of physics and the limitations of biomechanics are ignored here.

Attempts to convince readers and workers
that the quad-launch hypothesis cheats morphology and physics (as recounted here and at links therein) have so far failed. But I’m not giving up. So, if anyone has a connection to the NHM in London, please make this post available to alert them of their accidental foray into wishful thinking and inaccurate morphology.

References
National History Museum (NHM) in London

Why do pterosaur workers ignore the most basic data?

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

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

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

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

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

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

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

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

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

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

Dimorphodon model by David Peters

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

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

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

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

Figure 4. Galloping Dimorphodon by Mark Witton.

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

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

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

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

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

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

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

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

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

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

Padian 2017 examines pterosaur ankles with taxon and paper exclusion

I’ve had a long history with Dr. Kevin Padian,
one of the smartest paleontologists out there. He made important suggestions to my first book, GIANTS and early in his career made a name for himself by reporting on the bird-like traits of the Jurassic pterosaur, Dimorphodon. 

Unfortunately
Dr. Padian has a blind spot. He holds to the invalidated hypothesis that pterosaurs are related to dinosaurs, despite the complete lack of a series of archosaur taxa demonstrating a gradual accumulation of pterosaur traits. He still believes in the clade ‘Ornithodira.’

Ornithodira
Wikipedia reports, “Gauthier…coined and defined a slightly more restrictive node-based clade, Ornithodira, containing the last common ancestor of the dinosaurs and the pterosaurs and all of its descendants. Paul Sereno in 1991 gave a different definition of Ornithodira, one in which Scleromochlus was explicitly added.”

In the large reptile tree (LRT, 1094 taxa) the last common ancestor of dinosaurs and pterosaurs is the Devonian tetrapod, Tulerpeton at the base of the Lepidosaurormorpha – Archosauromorpha split.

Padian 2017
once again links pterosaurs with dinosaurs as he reviews with old illustrations the ankle bone ‘homologies’ of pterosaurs and archosaurs. Unfortunately he ignores Peters (2000a, b) who reidentified certain tarsals based on homologies with Cosesaurus and other fenestrasaurs (see below).

Figure 4. Peteinosaurus and Dimorphodon BMNH4212 pedes. Four tarsals are present on both.

Figure 1. Peteinosaurus and Dimorphodon BMNH4212 pedes. Four tarsals are present on both.

From the Padian abstract:
“The ankle bone assembly of pterosaurs has received little attention, even though it is critical for understanding the functional morphology of the leg and the foot and has far-reaching implications for interpretations of stance and gait in ornithodirans in general, as well as for any role the leg may have had in the flight of pterosaurs. Of particular importance are the distal tarsal bones, which are seldom preserved clearly.”

Padian found only two large (medial and lateral) tarsals in Dimorphodon, but most early pterosaurs have four tarsals (Fig. 1), as some of his figures show.  In Dimorphodon and Pteranodon the distal and proximal tarsals appear to fuse to one another creating two large side-by-side tarsals with a concave surface for articulation with the tibia/fibula. In all other pterosaurs the proximal tarsals are the astragalus and calcaneum. The ‘distal tarsals’ are actually distal tarsal 4 + the centrale sometimes accompanied by a tiny distal tarsal 3 (Peters 2000a) based on homologies with several tritosaur lepidosaurs, like Macrocnemus.

“Their concave proximal facets articulate with the medial and lateral condyles (comprising the astragalus and, at least basally, the calcaneum) of the tibiotarsus.”

The proximal tarsals are not part of the tibia in pterosaurs. Pterosaurs do not fuse the tibia and tarsus to form a tibiotarsus (Peters 2000a).

“Distally, they articulate with metatarsals II–IV, and the relatively large metatarsal V articulates on the distolateral side of the lateral distal tarsal.”

Not quite. That’s distal tarsal and the calcaneum articulate with metatarsal 5. That is exactly what happens, as Padian shows, in the archosauriforms Euparkeria, Crocodylus and Lagerpeton. That is exactly what also happens in the tritosaurs HuehuecuetzpalliMacrocnemus, Langobardisaurus, Cosesaurus and Sharovipteryx (Peters 2000a and ReptileEvolution.com).

“The homology of these bones in pterosaurs can be established with reference to other early-branching ornithodirans, and the morphology of the bones implies similar functional roles and ranges of motion.”

Convergence here with tritosaur lepidosaurs. Worth looking at.

“The medial distal tarsal is likely the fusion of distal tarsals 2 C 3, and the lateral distal tarsal is distal tarsal 4, a pattern reflected in ontogeny.”

No and yes. In tritosaurs distal tarsals 1–3 are tiny vestiges. Distal tarsal 3 is retained in many long-tailed pterosaurs. Distal tarsal 4 remains large. The proximal and distal elements fuse in Pteranodon. The medial centrale is Padian’s medial distal tarsal (Peters 2000a).

“The pterosaur ankle was capable of plantarflexion, but adduction and abduction of the feet were greatly limited.”

True.

“A synoptic survey of available tarsal bones of pterosaurs shows that the morphology of these bones remained relatively unchanged from the most basal pterosaurs to the pteranodontids and the azhdarchoids.”

True.

“Comparisons among a variety of ornithodirans show that the basic functional pattern did not vary importantly, although some ornithodiran subgroups evolved unique schemes of development and sequential ossification.”

True.

Dr. Padian writes:
“Pterosaurs were not thought to be particularly close to dinosaurs, or to any other archosaurs.”

When? That’s not current and traditional.

“Bennett, as noted above, does not accept that pterosaurs are ornithodirans. So it is all the more striking that these authors come to the same conclusion as functional morphologists who accept that pterosaurs are ornithodirans. The consensus of these authors is that pterosaurs, like dinosaurs and other ornithodirans, had a mesotarsal ankle that functioned as a hinge joint. Because the knee was also a hinge joint, as were the metatarso-phalangeal joint and the interphalangeal joints (Padian, 1983b, 1991), and the hip joint effectively allowed only protraction and retraction (see Schaeffer, 1956, and also Padian, 1983b), the gait would have been parasagittal and the stance erect (Padian, 2008). No argument has ever been made to counter these observations.”

No argument can be made to counter these observations. However, they can be expanded. Padian ignores the fact that other clades, like lepidosaurs, are also capable of bipedal locomotion and that some (like those list above) also have a simple hinge ankle joint. He also fails to note that in some pterosaurs the femoral head is at right angles to the shaft, but in others it is almost in line with the shaft, creating a splayed femur, like a lepidosaur, yet, like certain lepidosaurs, still capable of erect bipedal locomotion (Fig. 2).

Padian discusses the splayed femur concept
and agrees with Unwin that it would have provided a clumsy, sprawling gait. This is incorrect as anyone can learn from making museum-quality skeletons that have splayed femora and erect hind limbs. The angles all work out (Fig. 2).

And running bipedal lizards are not clumsy. They are speedy wonders!

Standing Pteranodon

Figure 2. Standing Pteranodon with sprawling femora. We’ve known this for 17 years.

Way back in the 1980s,
Kevin Padian and Chris Bennett. in the same conversation. cautioned me to employ phylogenetic analysis in my studies. Given present data in the academic literature (Peters 2000a, b) you have to ask yourself why Padian, like Bennett (2012) restricted his taxon list to just archosauromorphs.

For those who wonder why I don’t publish,
maybe Padian’s paper will offer some insight. I have published several papers on pterosaur relationships, wings and feet. None were cited by Dr. Padian. He is listed in the acknowledgments of Peters 2000a for reading an earlier version of the manuscript. The last time we e-mailed he was angry that I made several of the above observations.

References
Bennett SC 2012. The phylogenetic position of the Pterosauria within the Archosauromorpha re-examined. Historical Biology. iFirst article, 2012, 1–19.
Padian K 1983. 
Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Museum, Postilla, 189: 1-44.
Padian K 2017.
Structure and evolution of the ankle bones in pterosaurs and other ornithodirans. Journal of Vertebrate Paleontology.
DOI: 10.1080/02724634.2017.1364651
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.

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.

Eurazhdarcho and LIPB R 2.395: two new azhdarchid pterosaurs

Two European azhdarchids
have become known recently. Eurazhdarcho langendorfensis EME VP 312/2 (Vremir et al. 2013, Fig. 2) and the unnamed LIPB R 2.395 (Vremir et al. 2015. Fig. 1). Eurazhdarcho is known from a distal mc4, a proximal m4.1 and a proximal mt3 (not a distal mc3 as originally labeled, see below), plus cervicals 3 and 4. LIPB R 2.395 is known from a cervical 4 only.

What little is known indicate that both are similar in size and proportions to Zhejiangopterus. And they are just as gracile.

Figure 1. LPB-(FGGUB)-R.2395 cervical 4 with other cervicals imagined.

Figure 1. LPB-(FGGUB)-R.2395 cervical 4 with other cervicals imagined.

The re-identification
of distal metacarpal 3 in Eurazhdarcho (Figs. 2, 3) as metatarsal 2, 3 or 4 is based on the shape of the bone in question. It is expanded asymmetrically proximally and flattened as preserved in situ in Eurazhdarcho (Figs 2, 3) and Quetzalcoatlus (Fig. 4). By contrast distal metacarpal 3 in all pterosaurs has a convex articular surface to accommodate an unrestricted metacarpophalangeal 3 joint permitting extreme extension for implanting posteriorly while walking.

Figure 2. Eurazhdarcho with mc3 reidentified as mt3.

Figure 2. Eurazhdarcho with distal mc3 (in red and in figure 3) re-identified here as proximal portion of metatarsal 2, 3 or 4.

The in-situ placement
of the bone in question (Fig. 2) on the fossil near metacarpal 4 cannot be valid evidence because the cervicals are also extremely displaced. These bones became a jumbled mess long after the body had disintegrated and these few scattered elements were fossilized.

Figure 3. Close up of bone labeled distal mc3. This looks more like proximal mt3.

Figure 3. Close up of bone labeled distal mc3 in Eurazhdarcho. This looks more like a proximal metatarsal in Quetzalcoatlus in figure 4. There is no spherical articulation surface here that would indicated a distal metacarpus. The pink area is a restoration that could represent a much longer distal metatarsal.

The metatarsus of Quetzalcoatlus (Fig 4)
provides comparable data for the Eurazhdarcho bone in question. Metatarsal 4 is shown because it shows better on the lateral edge of the foot. Metatarsal 3 lies beneath it. Both appear to be a good match.

Figure 3. Metatarsal 3 in Quetzalcoatlus looks like the same bone in Eurazhdarcho labeled as a distal metacarpal 3.

Figure 4. Metatarsal 3 in Quetzalcoatlus looks like the same bone in Eurazhdarcho labeled as a distal metacarpal 3. Click to enlarge.

Good to see
mid-sized azhdarchids in eastern Europe to go with the giant Hatzegopteryx, also known from scraps.

I sincerely hope
one of the authors of both papers, Darren Naish, is not too upset by this reinterpretation. We’ve heard from him before. I confess: I used DGS. Never saw the actual fossil. And I don’t have a PhD. Did I make a mistake? Let me know and a change will be made.

References
Vremir MTS, Kellner AWA, Naish D, Dyke G 2013. Laurent  V, ed. A New Azhdarchid Pterosaur from the Late Cretaceous of the Transylvanian Basin, Romania: Implications for Azhdarchid Diversity and Distribution. PLoS ONE 8: e54268.
Vremir MTS, Witton M, Naish D, Dyke G, Brusatte SL, Norell M and Totoianu R 2015. A medium-sized robust-necked azhdarchid pterosaur (Pterodactyloidea: Azhdarchidae) from the Maastrichtian of Pui (Haţeg Basin, Transylvania, Romania). American Museum Novitaes 3827 16 pp.